18th IPVS CONGRESS, HAMBURG, GERMANY, 2004

PMWS – Circovirus – PDNS
• Evaluation of differences in host susceptibility to PCV2-associated disease
• PCV2-associated disease following intrauterine infection
• Evidence of postweaning multisystemic wasting syndrome (PMWS) in Norway
• Finishing pigs systems research: health and welfare
• First description of porcine circovirus type 2 (PCV2) associated diseases in Bulgaria
• Sow impact on litter mortality in a swine integration system experiencing postweaning multisystemic wasting syndrome (PMWS)
• Diagnosis of PMWS by PCR: PCR for PCV2 should not be used for diagnosis of PMWS
• Safety of high dose administration of an inactivated adjuvanted PCV2 vaccine in conventional gilts
• Safety of a repeated overdose of an inactivated adjuvanted PCV2 vaccine in conventional pregnant gilts and sows
• Effect of timing of vaccination with commercially available bacterin on PCV2-associated lesions
• Studies concerning PMWS rapid diagnostic tools and epidemiology
• Does genetics or litter effects influence mortality in PMWS?
PRRS
• Infection and reinfection with homologous and heterologous porcine reproductive and respiratory virus (PRRSV) strains: practical aspects
• Seroepidemiological study of PRRS infection patterns in nursery pigs
• Impact of genetic diversity of European-type porcine reproductive and respiratory syndrome virus strains on vaccine efficacy
• Comparison of 4 ELISAs for detection of antibodies against PRRSV in pig herds with different situations of PRRSV infection
• Differential diagnosis of PRRS field virus strains and modified live vaccines in Europe
• PRRSV rORF specific ELISA antibody responses following repeated homologous wild-type virus challenges
• Circulation of two genotypes of PRRSV within swine herd in Lithuania
• Eradication of PRRS in a French pig herd: use of a killed vaccine and massive sow replacement
• Potential influence of repeated vaccination against PRRS on the detection of virus infected sows in French herds proposed for eradication
• Field evaluation of vaccination against PRRS with an inactivated PRRS vaccine in a Dutch breeding herd
• Evaluation of antibody responses in PRRSV-exposed sows, their colostrum and 3 to 4 day-old piglets following the use of killed PRRSV vaccine (part 1)
• Duration and protection of maternally derived antibodies in pigs farrowed from PRRSV-exposed sows following killed PRRSV vaccine administration (part 2)
• The safety and efficacy of simultaneous PRRS (Progressis®) and PPV/Erysipelas (Parvoruvac®) vaccination in endemically PPRSV infected breeding herds
• Qualification and evaluation of a new PRRSV IgM IPMA test
• PPRSV-specific and persistent TH1 cell response in pigs following PRRSV infection and/or vaccination with an inactivated PRRS vaccine
• PRRS-specific cell response following PRRSV infection and/or vaccination with an inactivated PRRS vaccine: (2) characterization of the PRRSV-specific responding cells
• The effect of vaccination of sows with a PRRSV inactivated vaccine on their health status and performance in a farm with endemic PRRS
• A safety study on the effects of vaccination of boars with a PRRSV inactivated vaccine on the characteristics and fertilizing capacity of their semen
• The effect of vaccination of sows with a PRRSV inactivated vaccine on litter characteristics in a farm suffering from endemic PRRS
• Homologous PRRSV challenge after vaccination with an inactivated PRRS vaccine: Progressis®Merial
• Gilt acclimatization under field conditions in Spain
• Field evaluation of mass vaccination against PRRS and parvovirosis in sows as compared to the recommended schedules
• PRRS virus immunology research and the swine veterinarian
Classical Swine Fever
• Analytical performance of several laboratory diagnostic techniques on live animals for early detection of a classical swine fever
Swine influenza
• Serological evaluation of a vaccination protocol for swine influenza virus in fattening pigs
Porcine parvovirus
• Porcine parvovirus vaccination-challenge experiment using an adjuvanted inactivated combo vaccine: Parvoruvax® (Merial)
Mycoplasma hyopneumoniae
• Vaccination against Mycoplasma hyopneumoniae in a fattening herd with high lung score at slaughter
• The use of serum profiles to estimate the age of vaccination against Mycoplasma hyopneumoniae
• Long-term protection against Mycoplasma hyopneumoniae by two vaccination programs in Parma’s ham production system
Welfare
• Pig welfare – Past, present, future
Production
• Public perception of pig production – Past, present, future; challenge for pig production in the future
• Reproductive problems in primiparous sows
• Mycotoxins – A menace to pig production
Miscellaneous
• Influence of antimicrobial use on resistance in pig herds

Evaluation of differences in host susceptibility to PCV2-associated disease
OPRIESSNIG T, ANDERSON MS, ROTHSCHILD MF, EVANS RB, FENAUX M, MENG XJ, HALBUR PG
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:12
Duroc, Landrace, and Large White pigs were inoculated with PCV2 at 5-7 weeks of age in order to compare the impact of PCV2 infection on each breed. The comparison was based on clinical signs and severity of gross and microscopic lesions. Landrace pigs seem more susceptible to PCV2-associated lymphoid depletion and PMWS than Duroc and Large White pigs.

PCV2-associated disease following intrauterine infection
NIELSEN J, LADEKJÆR HANSEN AS, BILLE-HANSEN V, LOHSE L, BØTNER A
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:14
Two PCV2-seropositive gilts were inoculated intranasally with PCV2 at 72 and 92 days of gestation respectively. Piglets born of these two gilts were blood sampled prior colostrum intake and then weekly until 5 weeks of age. They were followed clinically and necropsied. Tissue samples were submitted to virological and histopathological examination and immunohistochemical detection of PCV2. The presence of PCV2-antigen was investigated in serum from the 2 gilts and their piglets by quantitative PCR. Intrauterine infection did take place in one of the two gilts (gilt inoculated at 72 days of gestation) demonstrating that PCV2 can cross the transplacental barrier. In addition, PCV2-infected liveborn piglets died from PCV2-associated lesions during the experiment which indicates that PCV2-associated diseases can occur following intrauterine infection with PCV2. Since semen was not checked for PCV2 contamination, a possible contamination through this iroute can not be absolutely ruled out.

Evidence of postweaning multisystemic wasting syndrome (PMWS) in Norway
BRUNBORG IM, MOLDAL T; JONASSEN CM, GUDMUNDSSON S, LIUM B, BRATBERG B
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:48
First report of PMWS in Norway. The actual prevalence of PCV2-infection in Norway is currently unknown but is suspected to be very high.

Possible prevention of PMWS using inactivated PCV2 vaccine in CDCD pigs
POGRANICHNIY R, YOON KJ, YAEGER M, VAUGHN E, HARMON K, STAMMER R, ROOF M
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:55
The safety and efficacy of two experimental PCV2 vaccines inactivated either by chemical process (BEI) or ultraviolet (UV) irradiation were evaluated in caesarian derived colostrum deprived (CDCD) pigs. Co-infection and immunostimmulation were respectively reproduced with an injection of PRRSV and an injection of keyhole limpet hemocyanin (KLH) combined with incomplete Freund’s adjuvant. All groups but one were challenged with PCV2 at day 24. The treatment groups were as follows:

ADG in groups 1 and 2 was identical to that of group 6 (non-vaccinated, non-challenged pigs) whereas ADG in groups 3 and 4 was significantly lower. None of the surviving pigs of groups 1 and 2 had microscopic lesions typical of PMWS in lymph nodes and lungs and were negative for PCV2 by IHC whereas all surviving pigs of group 5 showed microscopic lesions and were PCV2-positive. PCV2 inactivated vaccines may be a way of minimizing PCV2-associated diseases.

First description of porcine circovirus type 2 (PCV2) associated diseases in Bulgaria
MOTOVSKI A, SEGALES J
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:73
Eight farms located in various areas of Bulgaria were investigated for the presence of PMWS and PDNS. PMWS was diagnosed in three farms and combined PMWS/PDNS in one farm. All of these farms had high postweaning mortality (>30%) and pigs with typical PMWS clinical signs and histopathological lesions. PCV2 infection seems thus to be widely present in Bulgarian pig herds but the actual impact on pig industry is to be determined.

Sow impact on litter mortality in a swine integration system experiencing postweaning multisystemic wasting syndrome (PMWS)
CALSAMIGLIA M, SEGALES J, FRAILE L, ESPINAL A, SEMINATI C, MARTIN M, MATEU E, DOMINGO M
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:78
The litter effect in sows from a PMWS-affected swine integration system was assessed with regards to PCV2 viremia, PCV2 antibody level and parity of sows. Viremic sows had a significantly higher number of dead piglets per litter when compared to non-viremic sows and so did sows with low or no antibodies against PCV2 compared to sows with high levels of antibodies against PCV2. Sow parity had no effect on piglet mortality. These results show that PCV2 infectious and humoral immune status of sows at farrowing clearly contribute to the litter effect. Therefore, a reduction of PMWS impact on piglet mortality may be achieved by increasing maternal immunity and reducing sow viremia at farrowing.

Diagnosis of PMWS by PCR: PCR for PCV2 should not be used for diagnosis of PMWS
CAPRIOLI A, MCNEILLY F, MCNAIR I, MCKILLEN J, LAGAN P, ASKIN C, ELLIS J, ALLAN G
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:80
Blood samples, fecal swabs and tonsil swabs were collected in experimentally PCV2-infected pigs and examined by a non-quantitative PCR for PCV2 DNA. A 25 days post-infection the pigs were euthanized and tissue samples were submitted to histopathological examination and immunofluorescence for PCV2 antigen. No correlation could be demonstrated between the results of the non-quantitative PCR and the occurrence of PMWS confirming that PCR for PCV2 is not a suitable tool for diagnosis of PMWS.

Safety of high dose administration of an inactivated adjuvanted PCV2 vaccine in conventional gilts
REYNAUD G, BESEME S, BRUN A, CHARREYRE C, DESGOUILLES S, JEANNIN P, REHBEIN S
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:87
No local or general adverse reaction were observed after one injection of a high dose of a PCV2 vaccine candidate in conventional seropositive gilts. Single vaccination significantly increased already high serological responses to PCV2. This vaccine may be useful to ensure constant and high antibody titers in farms in which PCV2 is already circulating.

Safety of a repeated overdose of an inactivated adjuvanted PCV2 vaccine in conventional pregnant gilts and sows
REYNAUD G, BRUN A, CHARREYRE C, DESGOUILLES S, JEANNIN P
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:88
Ten conventional pregnant gilts and sows with high anti-PCV2 ELISA antibody titers were inoculated 4 weeks and two weeks before expected farrowing with an overdose of an inactivated adjuvanted PCV2 vaccine and compared to 10 control animals inoculated with placebo following the same schedule. In this experiment, the repeated injection of an overdose of an inactivated adjuvanted PCV2 vaccine was safe for pregnant gilts and sows and had no effect on their piglets.

Effect of timing of vaccination with commercially available bacterin on PCV2-associated lesions
OPRIESSNIG T, MENG XJ, HALBUR PG
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:96
The use of vaccines against Mycoplasma hyopneumoniae has already been demonstrated to enhance the clinical and histopathological impact of PCV2 infection. This experiment was designed so as to compare the effect of different timings of vaccination with a M. hyo bacterin (M+PAC® Schering-Plough Animal Health, Inc.) in pigs challenged with a PCV2 isolate at 8 weeks of age. The authors conclude that lowest impact of PCV2 infection was obtained in pigs vaccinated 4-2 weeks prior to challenge i.e. 2-shot vaccination at 4 and 6 weeks versus 2-4 weeks and 8-10 weeks of age.

Note from FJ: it can be also interpreted as early immune stimulation as well as vaccination at the time clinical sign use to occur do worsen the situation, as it is often seen in the fields

Studies concerning PMWS rapid diagnostic tools and epidemiology
CALSAMIGLIA M
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 2:807
PCV2 genome amplification and quantification was carried out in nasal, bronchial, tonsillar, fecal and urinary swabs and blood samples from 142 pigs sent to the Veterinary Diagnostic Service at the Universitat Autònoma de Barcelona with various clinical conditions. Tonsil, superficial inguinal lymph node, liver and spleen samples were investigated for PMWS lesions. Animals with characteristic PMWS lesions had significantly higher viral loads than animals without PMWS lesions. Bronchial swabs of pigs with PMWS lesions had significantly higher viral loads when compared to the that the other swabs. The results of this study strongly suggest the respiratory route to be the main route of excretion of PCV2. In addition, a strong correlation was found between viral load in all five excretion routes and viral load in serum.

Does genetics or litter effects influence mortality in PMWS?
ARMSTRONG D, BISHOP SC
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 2:809
This study was based on the data collected in a sow commercial farrow-to-finish farm experiencing a PMWS outbreak. The data regarded 16278 piglets weaned piglets in 1637 litters over an almost 3-year period. Piglet mortality due to PMWS was found significantly lower in sows with parity 1 and 2 than in sows with later parities suggesting that piglets born of older sows receive less colostral protection. No genetic effect was demonstrated on this farm.

Infection and reinfection with homologous and heterologous porcine reproductive and respiratory virus (PRRSV) strains: practical aspects
PESENTE P, SANDRI GP, SPERATI RUFFONI L, CAMPAGNARI E
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:24
Ten initially PRRSV-negative pigs of 21 days of age were intramuscularly inoculated with a strain of PRRSV (strain A). Animals were monitored for clinical signs, the presence of PRRSV in blood and in oropharyngeal scrapings by nested-PCR and immune response by ELISA. Pigs were inoculated again with the same strain at day 140 and two weeks later (day 154) with an heterologous strain (strain B showing 7.8% difference in its amino acid sequence with strain A). Following re-infection with the homologous strain, none of the pigs showed clinical signs suggesting that protection against an homologous strain lasts at least 140 days. Following challenge with the heterologous strain, no clinical signs were observed but viremia was prolonged and a significant seroconversion occurred in all animals which can then excrete this heterologous strain of PRRSV. The response to a heterologous strain is clearly different from that to the homologous strain. As a consequence, acclimatization of replacement animals is to consider a critical step and particular care should be taken to introduce only pigs acclimatized with the homologous strain. Testing oropharyngeal scrapings by nested-PCR appears a useful tool for the identification of carrier animals.

Seroepidemiological study of PRRS infection patterns in nursery pigs
DEWEY C, MELNICHOUK O, FRIENDSHIP R, HAYDEN D
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:32
In each of the 8 commercial herds included in this study, 80-120 piglets were blood sampled every week from their first week of life until 10-11 weeks of age. All samples were tested by IDEXX ELISA. Two different patterns of spread of PRRSV were observed, i.e. a rapid and a slow spread. Farms with slow spread had only 20-40% of their piglets infected by the end of the nursery stage while farms with rapid spread had already 50% of their piglets infected by 4-7 weeks of age and more than 90% at 8.5 weeks of age. The linear infection model appeared the most suitable one to explain the spread of PRRSV through the nursery period in the rapid pattern. The type of pattern (rapid or slow) was not linked to management factors.

Note from FJ: This must be related to the work done with P. Candotti and presented in European meeting (SIPAS-AFMVP) showing that high % of seropositive piglets at 9-10 weeks of age is linked with reproductive disorders due to PRRSV circulation. Final interpretation choosing between more piglets positive at weaning that contaminating more easily their penmates vs a difference in diffusibility of certain strains must be further investigated.

Impact of genetic diversity of European-type porcine reproductive and respiratory syndrome virus strains on vaccine efficacy
LABARQUE G, VAN GUCHT S, VAN REETH K, DREXLER C, NAUWYNCK H, PENSAERT M
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:33
To date, three clusters of European PRRSV isolates have been identified namely the Lelystad, the Danish and the Italian clusters. In this study, PRRSV-negative conventional pigs were vaccinated with a European-type vaccine belonging to the Lelystad cluster (Porcilis®PRRS, Intervet NV) and subsequently challenged either with a Lelystad strain or an Italian strain and compared to non-vaccinated controls which were also inoculated with either one or the other strain. PRRSV titers were determined in broncho-alveolar lavage (BAL) fluids and sera. While in the Lelystad-challenged pigs the virus was not present in neither BAL fluids nor sera, in the Italian-challenged pigs the virus was detected in both of them. Virus titers were anyway lower in these vaccinated pigs when compared to the control pigs. Therefore the vaccine efficacy does depend on the genetic and antigenic similarity between the vaccine and the challenge strain. A close monitoring of PRRSV strains is necessary to guarantee that PRRSV vaccines provide an acceptable level of protection in the field.

Comparison of 4 ELISAs for detection of antibodies against PRRSV in pig herds with different situations of PRRSV infection
DE WIT JJ, CIA C, BOLINK GJ, DE JONG MF,, DONADEU M
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:34
The genomic and antigenic variability of PRRSV strains hinders the development of a diagnostic test capable of detecting antibodies directed against all strains of PRRSV. Several ELISAs are available for the detection of PRRSV antibodies but their performance need to be further investigated. Two of the PRRSV antibody ELISAs included in this study were developed to detect PRRSV group specific antibodies whereas the other two were developed to detect either the European strains or the American strains. The sera used in this study were obtained from 441 pigs originating from 5 PRRS-affected farms. The variation in the results obtained with the 4 ELISAs indicates that various factors such as the type of PRRSV strain, the phase of infection or even the test itself, may greatly influence the answer to the test.

Differential diagnosis of PRRS field virus strains and modified live vaccines in Europe
PESCH S, OHLINGER VF
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:35
The nucleotide sequence of the ORF5 of 120 European PRRSV isolates was determined and compared to that of Porcilis®PRRS modified live vaccine (MLV). Sequencing is a necessary step to differentiate field PRRSV strains from Porcilis®PRRS MLV due to their genetic similarity. Field strains were shown to share 79.5-96% homology with Porcilis®PRRS MLV while Porcilis®PRRS MLV-derived strains were shown to have 99.2-100% homology. Single site mutations in Porcilis®PRRS MLV were demonstrated to often occur resulting sometimes in a modification of the amino acid sequence. The use of modified live virus vaccine is thus strongly associated with the risk of genetic drift.

PRRSV rORF specific ELISA antibody responses following repeated homologous wild-type virus challenges
MCCAW M, MURTAUGH M, LASTER S, ROBERTS J, ERICKSON G
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:36
Previous studies have already shown that, following multiple immunizations with an homologous PRRSV strain, sows could still result ELISA seronegative a few weeks after the last immunization. This study reports the same results in 68 PRRSV-negative 6-month old barrows which received a total of 6 injections of the same PRRSV virulent strain each at a one-month interval. Blood samples collected in all animals 3 weeks following each injection were tested PRRSV ELISA and serum neutralization (SN) antibodies. Unlike ELISA antibodies, SN antibodies were still detected 4 months after the last immunization. In addition, ORF7 nucleocapsid protein curve was shown to follow that of ELISA antibodies whereas ORF5 envelope protein and ORF6 matrix protein were shown to have the same dynamic as SN antibodies. This suggest that the antibody response is initially directed against nucleocapsid protein and is subsequently redirected against envelope and matrix proteins, which could explain the rapid return to ELISA seronegative status observed in vaccinated or infected pigs. Consequently, a low ELISA antibody response following vaccination or infection could indicate a shift toward a protective immune response.

Circulation of two genotypes of PRRSV within swine herd in Lithuania
STANKEVICIUS A, STADEJEK T, PEJSAK Z
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:41
PRRSV is now widely spread in Lithuania with both European (EU) and American (US) strains circulating in swine herds. Lung samples from 2-3 month-old piglets with respiratory distress and blood samples from sows with reproductive failure were collected in a PRRS-affected farrow-to-finish farm which vaccinated sows with Ingelvac® PRRS modified live vaccine (Boehringer Ingelheim), and investigated by RT-nPCR and nucleotide sequencing. In 23.7% of the lung samples both EU and US PRRSV were identified. All sow serum samples were PRRSV negative. The US ORF5 sequence detected in piglets showed a high degree of similarity with Ingelvac® PRRS MLV and it was stated that the vaccine virus had spread from vaccinated sows to non-vaccinated piglets. The results of this study also demonstrates the lack of cross-protection provided by the vaccine since the presence of both EU and US strains was detected in piglets.

Eradication of PRRS in a French pig herd: use of a killed vaccine and massive sow replacement
LEBRET A, LACLADERE S, TESSIER P
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:91
The use of a killed vaccine together with sow replacement allowed to eradicate PRRS in a French pig herd from Brittany. From the economic point of view, this meant a 200€-benefit per sow for the farmer.

Potential influence of repeated vaccination against PRRS on the detection of virus infected sows in French herds proposed for eradication
LEBRET A, LACLADERE S, TESSIER P
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:92
Sows from a PRRSV-negative herd were submitted to the following vaccination schedule: priming and booster followed by an additional vaccination at 60-70 days of each gestation. They were serologically monitored during two gestations by IDEXX ELISA. Repeated vaccination with a killed vaccine was shown not to hinder the identification of PRRSV-positive sows by blood testing providing that sampling be done at least 3 months after the last injection. Therefore the use of a killed vaccine can be useful when associated to sow replacement in a context of PRRS eradication.

Field evaluation of vaccination against PRRS with an inactivated PRRS vaccine in a Dutch breeding herd
SEESING EHAL, VAN DER STEEN A, DE WIT T, JOISEL F, LONGO S
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:110
The reproduction parameters of a Dutch herd before and after the use of Progressis® (Merial) were compared. Despite an outbreak of swine influenza during the post-vaccination period, reproduction performance of the herd were shown to have improved following the use of Progressis®, confirming positive results already obtained in other countries.

Evaluation of antibody responses in PRRSV-exposed sows, their colostrum and 3 to 4 day-old piglets following the use of killed PRRSV vaccine (part 1)
NILUBOL D, VINCENT A, HARRIS H, THACKER B, THACKER E
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:112
Twenty sows from a PRRSV-positive herd were vaccinated with a killed PRRSV vaccine (PRRomiSe®, Intervet) while other 20 were kept as controls. The antibody level of sows was determined by SN assay and ELISA using two strains of PRRSV (the strain from which was designed the vaccine and another one), prior to vaccination, 3 days after farrowing and at weaning, that of their colostrum and their piglets was evaluated as well. A significant increase in antibody levels were observed in vaccinated sows against the vaccine strain. Colostrum of vaccinated sows had higher antibody titers against both strains and piglets born of vaccinated sows had significantly higher antibody levels against the vaccine strain. Higher antibody levels in sows and maternally derived antibody levels in their piglets were thus achieved with the use of a killed vaccine.

Duration and protection of maternally derived antibodies in pigs farrowed from PRRSV-exposed sows following killed PRRSV vaccine administration (part 2)
NILUBOL D, VINCENT A, HARRIS H, THACKER B, THACKER E
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:113
Piglets born of PRRSV-exposed sows vaccinated with a killed vaccine (PRRomiSe®, Intervet) were demonstrated to have an enhanced antibody responses with higher levels of maternally derived antibodies (MDA). The duration and the level of protection provided by such MDA were investigated by heterologous PRRSV challenge at various time points (10, 16 and 24 days of age) and successive RT-PCR for viral RNA and SN and ELISA for antibodies. A lower, but not significant, viral load was only observed in piglets born of vaccinated sows challenged at 10 days of age when compared to piglets born of non-vaccinated sows. Therefore, although the use PRRomiSe® in sows led to higher MDA in their piglets, it hardly resulted in any clear protection against PRRSV.

The safety and efficacy of simultaneous PRRS (Progressis®) and PPV/Erysipelas (Parvoruvac®) vaccination in endemically PPRSV infected breeding herds
GASS-COFRE A, GROßE-BEILAGE E, SCHREIBER A, NOE T
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:120
Vaccination programs allowing simultaneous administration of two vaccines would be a way of reducing the number of interventions and possibly of enhancing the efficacy of the vaccinations. The feasibility and potential benefits of such a procedure was evaluated for Progressis® (Merial) and Parvoruvac® (Merial) in 4 PRRSV-infecteds herd that had vaccinated for Erysipelas and Parvovirus for years but never vaccinated against PRRSV before. Safety was assessed using rectal temperature, local reactions, clinical signs and reproductive performance as parameters, efficacy was assessed with regards to reproductive performance (litter size, live born piglets and number of weaned pigs). Simultaneous administration of Progressis® and Parvoruvac® was demonstrated a safe schedule for sow herd vaccination. Regarding efficacy, a difference was observed according to the PRRS-status (stable versus unstable) of the herds with major increase in litter performance in herds with major extent of PRRS associated problems. The mean increase in weaned pigs per litter reached 0.4 in all herds.

Qualification and evaluation of a new PRRSV IgM IPMA test
MIELI L, BAUDOUARD M, LEBON E, JOISEL
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:127
Currently, PRRSV antibody determination is based on the detection of IgG. However, such methods have been demonstrated to provide sometimes questionable results. The use of an IgM immunoperoxidase monolayer assay (IPMA) was evaluated with sera from experimentally PRRSV-infected pigs collected at different days post-infection. The results obtained by this technique were similar to those obtained by other previously described IgM detection techniques, i.e. immunofluorescence antibody (IFA) assay. The authors recommend the use of IPMA in association with PCR in order to differentiate between recent infections and stabilized infections as well as between passive immunity and active seroconversion in post-weaning pigs up to 10 weeks.

PPRSV-specific and persistent TH1 cell response in pigs following PRRSV infection and/or vaccination with an inactivated PRRS vaccine
JUILLARD V, PIRAS F, ANDREONI C, CHARREYRE C, JOISEL F
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:137
A protocol based on the use of Progressis® (Merial) and including 3 groups of 7 pigs was designed as follows: group 1 was not vaccinated and kept as control, group 2 was vaccinated at D0 and D21, group 3 was vaccinated at D42 and D57, all 3 groups were challenged with an homologous PRRSV strain at D35. PRRSV-specific IFN?+ T cell responses were monitored by a porcine IFN?-ELISpost assay. Interestingly, the magnitude of PRRSV-specific IFN?+ T cell responses was not affected by PRRSV challenge suggesting that even in a contaminated environment vaccination with Progressis® provides a substantial and persistent PRRSV-specific IFN?+ T cell response in pigs.

PRRS-specific cell response following PRRSV infection and/or vaccination with an inactivated PRRS vaccine: (2) characterization of the PRRSV-specific responding cells
JUILLARD V, PIRAS F, ANDREONI C, CHARREYRE C, JOISEL F
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:138
Pigs vaccinated with an inactivated PRRSV vaccine (Progressis®, Merial) either before of after challenge with an homologous PRRSV strains were previously shown to both develop a strong PRRSV-specific IFN?+ T cell response. In this study, the nature of the PRRSV-specific IFN?+ T cell response induced by various PRRSV immune stimulations (challenge, vaccination/challenge and challenge/vaccination) was investigated. CD4+CD8+ cells and CD8high+ cells were shown to be the two types of T lymphocytes involved in PRRSV-specific IFN?+ T cell response following PRRSV infection and/or vaccination.

The effect of vaccination of sows with a PRRSV inactivated vaccine on their health status and performance in a farm with endemic PRRS
PAPATSIROS VG, KOPTOPOULOS G, ALEXOPOULOS, LONGO S, JOISEL F, KYRIAKIS SC
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:144
Vaccination of sows and gilts with Progressis® (Merial) in a farm with endemic PRRS allowed to reduce the incidence of early farrowing and to lower the culling rate confirming the ability of Progressis® to improve the reproductive parameters in PRRS-affected herds.

A safety study on the effects of vaccination of boars with a PRRSV inactivated vaccine on the characteristics and fertilizing capacity of their semen
PAPATSIROS VG, KOPTOPOULOS G, ALEXOPOULOS, LONGO S, JOISEL F, KYRIAKIS SC
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:145
Rectal temperature, semen characteristics (volume, density, viability and motility) and fertilizing capacity served as parameters to evaluate the effect of Progressis® (Merial) in boars. It was clearly demonstrated that vaccination of boars with Progressis® had no effect on primary reproductive parameters.

The effect of vaccination of sows with a PRRSV inactivated vaccine on litter characteristics in a farm suffering from endemic PRRS
PAPATSIROS VG, KOPTOPOULOS G, ALEXOPOULOS, LONGO S, JOISEL F, KYRIAKIS SC
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:146
This study was carried out in a 1000-sow, farrow-to-finish, PRRSV-infected pig farm in which all gilts and sows were vaccinated with Progressis® (Merial). Litter size and characteristics at birth and at weaning were recorded before and after the vaccination period. Unlike modified live vaccines (MLV), Progressis® (inactivated vaccine) was shown not to have negative effects on the health of sows and gilts even when administered during gestation. In addition, vaccination with Progressis® led to a significant increase in the litter size and litter performance, as a result of improved health status and body conditions of piglets.

Homologous PRRSV challenge after vaccination with an inactivated PRRS vaccine: Progressis®Merial
REYNAUD G, CHARREYRE C, TEDESCHI L, BRUN A, JOISEL F, JEANNIN P
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:429
In both PRRS-free and contaminated environments, vaccination of pigs with Progressis® (Merial) consisting of two shots at a 3-week interval, was shown to significantly reduce the percentage of viremic animals which further confirms that vaccination with Progressis® may be highly beneficial for the control of PRRS in the field.

Gilt acclimatization under field conditions in Spain
BERNAL R, CALLEN A
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 2:605
This study consisted in determining the effect of vaccinating PRRSV-negative gilts with Progressis® (Merial) before their introduction into a PRRSV-positive farm when compared to another farm with similar health status, in which restocking gilts were introduced without being vaccinated. The fertility rate was significantly higher in the group of vaccinated gilts. Seroconversion occurred later in vaccinated gilts than in non-vaccinated gilts. Moreover, while reproduction disorders were observed in the non-vaccinated gilt farm, the situation remained normal in the vaccinated-gilt farm. The use of Progressis® was thus beneficial and allowed to minimize acclimatization disorders in PRRSV-negative gilts introduced in a PRRSV-positive herd.

Field evaluation of mass vaccination against PRRS and parvovirosis in sows as compared to the recommended schedules
KEITA A, PAGOT E, ORVEILLON FX, POMMIER P, JOISEL F, HERIN JB
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 2:638
The administration of the booster injection of two vaccines, namely Progressis® and Parvoruvax® (Merial), is usually recommended at mid gestation and during lactation respectively. The effect of simultaneous administration of the two vaccines was evaluated in three farrow-to-finish French herds which usually vaccinated their animals against PRRS and parvovirosis following the recommended schedule for each vaccine. In each farm, two groups of sows were formed in which sows received the vaccines either simultaneously (group S) or separately (group C). No significant difference was observed between groups regarding reproductive results, rectal temperatures and local reaction after injection and serological responses. The safety and efficacy of simultaneous vaccination with Progressis® and Parvoruvax® was thus clearly demonstrated in this study.

PRRS virus immunology research and the swine veterinarian
MURTAUGH MP
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 2:812
Up-to-date knowledge about humoral and cellular immune response to PRRSV and potential ways to be investigated to improve vaccination and diagnostics of PRRSV.

Analytical performance of several laboratory diagnostic techniques on live animals for early detection of a classical swine fever
DEWULF J, KOENEN F, MINTIENS K, DENIS P, RIBBENS S, DE KRUIF A
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:342
Several assays were evaluated with regards to their ability of detecting truly CSFV-infected pigs: virus isolation in different blood fractions (whole blood, leukocytes, serum, plasma), Ag ELISA, leukocyte count for leukopenia and RT-nPCR. None of them were able to detect all infected pigs. RT-nPCR resulted able to detect the higher proportion of infected animals (98.9%). However RT-nPCR remains an expensive and time-consuming diagnostic technique. Further developments of this technique should allow to ease its use for more complex situations in the near future.

Serological evaluation of a vaccination protocol for swine influenza virus in fattening pigs
BARIGAZZI G, FONI E, OSTANELLO F, MANTOVANI G, SPERATI RUFFONI L, LEOTTI G
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:455
In Italian pigs, the growing period is extended up to 9 months of age which leads to a weakening of the immune protection against swine influenza virus provided by the usual two-shot vaccination schedule. The efficacy of a third shot administered at six months of age was thus evaluated. At their introduction into the herd, 32 pigs of 10 weeks of age were distributed into 2 groups, each group being subsequently subjected to a different vaccination protocol. Pigs of one group were vaccinated three times with AKIPOR®FLU (Merial) at 80, 110 and 190 days of age while the remaining pigs were vaccinated twice with AKIPOR®FLU (Merial) at 80 and 110 days of age and once with AKIPOR® (Merial) at 190 days of age. The results show that a third vaccination at 6 months of age with AKIPOR®FLU (Merial) induces higher specific antibody levels, better immune protection and thus can help to reduce economic loss due to potential infections with swine influenza virus occurring at the end of fattening.

Porcine parvovirus vaccination-challenge experiment using an adjuvanted inactivated combo vaccine: Parvoruvax® (Merial)
JOISEL F, BRUN A
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:430
In order to assess the efficacy of Parvoruvax® (Merial) nine gilts were vaccinated twice at a 3-week interval, mated 3 weeks after the second injection and then challenged at about 40 days of gestation with a field PPV isolate. A non-vaccinated group of sows was kept as control. All sows were euthanized at about 90 days of gestation. Blood samples from the sows and from their fetuses were tested by hemagglutination inhibition (HI) and fetal tissue samples subjected to ELISA for PPV. Non-vaccinated sows had a significantly higher number of mummified fetuses and significantly lower mean number of live fetuses. In addition, 93% of the fetuses recovered from the non-vaccinated sows were found PPV-infected versus only 12% in the vaccinated group. The results of this study further confirm that Parvoruvax® effectively prevents the intrauterine establishment of PPV infection, fetal damage and thus reproductive failure.

Vaccination against Mycoplasma hyopneumoniae in a fattening herd with high lung score at slaughter
LINDBERG M, LUNDEHEIM N, ELIASSON-SELLING L, HELLANDER J, WALLGREN P
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:239
Seroconversion to Mycoplasma hyopneumoniae (Mhyo) was previously shown to often occur during the fattening period. A vaccination protocol consisting of one injection of Hyoresp® (Merial) administrated to all pigs at their arrival in a fattening herd with high prevalence of SEP lesions at slaughter was applied from October 2000 to April 2003 in order to evaluate potential benefits of such a vaccination. The incidence of SEP at slaughter decreased from 15% to 2.4% indicating a clear positive effect of Mhyo vaccination.

The use of serum profiles to estimate the age of vaccination against Mycoplasma hyopneumoniae
UTRERA V, ANTILLANO C, CANO JP, CARRILLO R, DELCASTILLO S, FUENTES D, HEREDIA C, PIETERS M, ROJAS L, VILLALOBOS J, URRIOLA P, TERAN E
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:433
The level of maternal antibody is known to interfere with active immunization against Mycoplasma hyopneumoniae. An ELISA Tween 20 S/P value of 1.42 has been previously recommended as a cutoff value below which vaccination against Mycoplasma hyopneumoniae should not be impaired by maternal antibodies. The efficacy of vaccination programs abiding by this cutoff value was evaluated in three farrow-to-finish operations previously diagnosed with enzootic pneumonia, using average lung lesions at slaughter, average days to market and cough index as parameters of efficacy of vaccination. The results of this study confirm that the efficacy of vaccination against Mycoplasma hyopneumoniae is significantly improved when applied to piglets once antibody levels detected by ELISA Tween 20 are below S/P values of 1.42.

Long-term protection against Mycoplasma hyopneumoniae by two vaccination programs in Parma’s ham production system
NIGRELLI A, LEOTTI G, JOISEL F, LONGO S
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:444
The ability of the inactivated vaccine Hyoresp® (Merial), to provide long-term protection against M. hyo to heavy pigs raised until 9 months of age was evaluated in a farrow-to-finish Italian farm. A total of 829 piglets were distributed into 3 treatment groups as follows: group C in which animals were kept as non-vaccinated controls, group VP in which animals were vaccinated early (at 1 and 4 weeks of age) and group VT in which animals were vaccinated late (at 6 and 9 weeks of age). Lung lesion scores at slaughter were used as parameter and with a scale ranging from 0 to 4. A total of 505 lungs were examined. A significant difference was found between the control group and the vaccinated groups which had significantly lower lesion scores, while no significant difference was observed between the two vaccinated groups. Therefore, Hyoresp® was shown to provide a long-lasting protection against M. hyo in this particular kind of management.

Pig welfare – Past, present, future
GONYOU HW
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 2:769
Pig welfare is a subject of increasing concern and it has become an indissociable part of pig production. This paper reviews the foundations of the various welfare movements which have influenced pig production so far.

Public perception of pig production – Past, present, future; challenge for pig production in the future
HARTUNG J
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 2:774
Intensification, specialization and regional concentration are the three concepts that have been characterizing pig production in Europe over the last decades. Drastic changes in terms of management have occurred so as to satisfy the need for a growing supply of pork and achieve cost efficiency. All this process have had of course heavy consequences for animals and environment. The author paper considers all these aspects with some reference to the situation of pig raising in Germany.

Reproductive problems in primiparous sows
KEMP B, SOEDE NM
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 2:843
Several problems such as prolonged weaning to estrus interval, low pregnancy rates after insemination and steady or lower number of piglets at second farrowing affect gilts at the beginning of their reproductive carrier. In addition, the fact that gilts have concurrently significant nutrient needs for growth, lower feed intake capacity and lower metabolizable fat and proteins impairs lactation and has repercussions on their litter. The gap between actual needs and feed intake capacity of gilts is an aspect to work on in order improve reproductive performance of gilts.

Mycotoxins – A menace to pig production
VELDMAN C
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 2:855
Concise and clear review about mycotoxins produced by Aspergillus, Fusarium and Penicillium and their impact on swine production. Mycotoxin associated problems and the disease profiles that should lead a practitioner to suspect of mycotoxins are described as well as the available means of treatment and prevention. It is essential not to forget to consider mycotoxins as a potential cause of disorders in pigs. Efficient tools are available to react quickly and tackle mycotoxin related problems, do not hesitate in consulting a mycotoxin specialist!

Influence of antimicrobial use on resistance in pig herds
BELLOC C, DINH NL, PACOT C, BEHRA S, LAVAL A
Proceedings of the 18th IPVS Congress, Hamburg, Germany, 2004 - Volume 1:445
Fourteen farrow-to-finish French herds were classified as low-users, medium-users and high-users as regards to the use of antimicrobials. Fecal samples were collected from sows and pigs and the Escherichia coli strains isolated were tested for antimicrobial susceptibility to ceftiofur, cefquinome, florfenicol and colistin for which no or few resistance was demonstrated and amoxicillin, gentamicin, trimethroprim-sulfamethoxazol and tetracycline for which various levels of resistance were observed. In pigs, the level of antimicrobial use was found to have a significant effect on percentage of resistant E. coli from postweaning to the end of the fattening period.