VIROLOGIE

Swine Influenza
• Herd-level seroprevalence of swine-influenza virus in Korea
PRRS
• Characterization of the carrier state in porcine reproductive and respiratory syndrome virus infection
• Identification of radically different variants of porcine reproductive and respiratory syndrome virus in Eastern Europe: towards a common ancestor for European, American viruses
• Association between clinical signs and high serum titers of porcine reproductive and respiratory syndrome virus (PRRSV) in nursery pigs under field conditions
• Evidence for local spread of porcine reproductive and respiratory syndrome virus
PMWS/PDNS
• First evidence of porcine circovirus type 2 (PCV-2) infection of pigs in the Czech Republic by semi-nested PCR
• Porcine circovirus 2 infection in swine fetuses inoculated at different stages of gestation
• Detection of porcine circovirus types 1 and 2 in serum and tissue samples of pigs with and without postweaning multisystemic wasting syndrome
• Exudative epidermitis and porcine circovirus-2 infection in a Swedish SPF-herd
• First report of post-weaning multisystemic wasting syndrome and porcine dermatitis and nephropathy syndrome in pigs in Greece
• Detection of porcine circovirus 2 (PCV-2) DNA by nested PCR from formalin-fixed tissues of post-weaning multisystemic wasting syndrome (PMWS) pigs in Thailand
• Porcine dermatitis and nephropathy syndrome in Japan

Herd-level seroprevalence of swine-influenza virus in Korea
JUNG T, CHOI C, CHUNG HK, KIM J, CHO WS, JUNG K, CHAE C
Prev Vet Med 2002 53: 311-314
A nationwide survey was carried out in Korea to assess the seroprevalence of one subtype of swine influenza A virus: H1N1 virus in swine herd. An ELISA kit was used to test the 911 sera from finishing pigs in 130 swine farms covering the five country states. The results showed a high prevalence of the virus (93 out of the sampled herds were positive and a herd was considered positive if at least two of the sampled animals were positive), even higher than the virus prevalence reported in America and Denmark.

Characterization of the carrier state in porcine reproductive and respiratory syndrome virus infection
HORTER DC, POGRANICHNIY RM, CHANG CC, EVANS RB, YOON KJ, ZIMMERMAN JJ
Vet Microbiol 2002 86: 213-228
An experimental study was conducted to determine the carrier status of PRRSV infected pigs over a long period of time (105 days). PRRSV is known to produce persistent infection and the evaluation of the carrier state is useful for the protection of negative herd, the prevention and control of the disease. PRRS-free pigs (60) were intranasally inoculated with a virus supernatant. A control group (60) was kept for comparison. Various samples (serum, peripheral blood leucocyte, oropharyngeal scrapings,..) from animals were collected at different days PI (post-infection) and assayed for conversion to PRRS by VI (virus isolation) RT-nPCR (transcriptase-nested polymerase chain reaction) and swine bioassay. Virus antibody response was tested with an ELISA kit. The VI and swine bioassay results showed that 51 out the 59 virus-inoculated animals were PRRS virus carrier over the whole study period. The eight remaining pigs were positive for viral nucleic acid by RT-nPCR. However no difference in antibody response between carrier and non carrier was noted with ELISA. Consequently, reliable identification of carriers may be performed using the first three techniques but not ELISA.

Identification of radically different variants of porcine reproductive and respiratory syndrome virus in Eastern Europe: towards a common ancestor for European, American viruses
STADEJEK T, STANKEVICIUS A, STORGAARD T, OLEKSIEWICZ MB, BELAK S, DREW TW, PEJSAK Z
J Gen Virol 2002 83: 1861-1873
Previous study have reported the genetic diversity of EU-type PRRSV. This is confirmed by a new study involving two Eastern European strains from Poland and Lithuania. A total of 22 ORF5 segments of PRRSV from Poland, Germany, Great-Britain and Lithuania were sequenced as well as two EU-type live vaccines. Similarly, the ORF7 sequences of Polish and Lithuanian strains were determined. It was found that the Polish and especially the Lithuanian PRRSV ORF5 sequences were exceptionally diverse from any other European genotype. Also, the size of the ORF7 protein from Lithuanian PRRSV was intermediate between the European prototype (Lelystad virus) and the US-type ORF7 protein, thereby establishing a link between EU-US sequences and suggesting a probable evolution from a common ancestor.

Association between clinical signs and high serum titers of porcine reproductive and respiratory syndrome virus (PRRSV) in nursery pigs under field conditions
CUARTERO L. DEE S, DEEN J, RUIZ A, PIJOAN C
J Swine health Prod. 2002, 10: 119-122
The acclimatization of gilts is considered a good strategy to prevent a PRRS outbreak in a PRRS positive herd. A cross-sectional study was carried out with 120 pigs (2, 4, 6 weeks of age) from a herd experiencing PRRSV. Pigs were classified into for 4 categories (healthy pigs, healthy pigs with lymphadenopathy, sick pigs and sick pigs with lymphadenopathy) according to their clinical signs. Their antibody titers were also recorded. The main conclusion of the study was that pigs showing clinical signs of PRRSV and potentially serving as PRRSV source for gilt acclimatization were not necessarily viremic.

Evidence for local spread of porcine reproductive and respiratory syndrome virus
LAGER KM, MENGELING WL, WESLEY R
J Swine Health Prod. 2002, 10: 167-170
Indirect transmission of PRRSV in several herds had been previously reported. In a recent study, PRRSV was isolated in 25 isolates from seven local herds in north-east Iowa. The isolates were subsequently analysed by RFLP (restriction fragment length analysis) and a similar RFLP pattern was revealed in 6 out of the seven farms which were run independently from one another. An indirect area spread of the virus was concluded but the mode of transmission is yet to be discovered.

First evidence of porcine circovirus type 2 (PCV-2) infection of pigs in the Czech Republic by semi-nested PCR
CELER V, CARASOVA P
J Vet Med B Infect Dis Vet P 2002 49: 155-159
PCV-2 was detected in 37 out of 77 samples from inguinal lymph nodes and nasal swabs from Czech pigs by using a semi-nested PCR with a first and second round of amplification. PMWS had been diagnosed in a number of pigs providing 56 samples and it turned out that the samples from the pigs with the clinical disease were highly positive for PCV-2. The results of the first round were confirmed by a second re-amplification which detected the presence of PCV-2 DNA only in three more samples. DNA sequencing was then carried out to further confirm the specificity of the PCR test.

Porcine circovirus 2 infection in swine fetuses inoculated at different stages of gestation
SANCHEZ RE, NAUWYNCK HJ, MCNEILLY F, ALLAN GM, PENSAERT MB
Vet Microbiol 2001 83: 169-176
The aim of the present study was to verify whether PCV-2 can replicate in fetal tissues and cause damage to fetuses. Two fetuses were inoculated with PCV-2 in each of two seropositive sows (out of the 6 sows included) and the remaining fetuses were left uninoculated. Inoculation was performed at different dates (57, 75, 92 days of gestation). The results showed that PCV-2 was isolated from all PCV-2 inoculated foetuses. Serum, lung, heart, liver, spleen, kidney, lymph node samples collected were PCV-2 positive in all foetuses. However, infected cells were more numerous in fetuses inoculated at 57 d. than other fetuses. Also, lesions were observed only in the four fetuses inoculated at 57 d. The non-inoculated fetuses were seronegative. Evidence of a possible viral replication of the virus and subsequent damage to fetuses caused by the infection was thus brought. The gestational age was an important parameter in the extent of PCV-replication

Detection of porcine circovirus types 1 and 2 in serum and tissue samples of pigs with and without postweaning multisystemic wasting syndrome
CALSAMIGLIA M, SEGALES J, QUINTANA J, ROSELL C, DOMINGO M
J Clin Microbiol 2002 40: 1848-1850
Two major techniques (PCR and in situ hybridization) for PCV1 and PCV2 detection were compared in terms of sensitivity. Serum samples were tested by PCR and superficial inguinal lymph nodes from PMWS-free and PMWS affected pigs were examined by the two techniques. Generally, over 50% of samples were found positive for PCV-2. PCV-1 was detected in only three samples. PCR proved to be a more sensitive technique although both methods achieved high agreement. On the other hand in situ hybridization was more efficient in detecting the presence of PMWS microscopic lesions.

Exudative epidermitis and porcine circovirus-2 infection in a Swedish SPF-herd
WATTRANG E, MCNEILLY F, ALLAN GM, GREKO C, FOSSUM C, WALLGREN P
Vet Microbiol 2002 86: 281-293
An unexpected outbreak of Exudative Epidermatitis (EE) occurred in a SPF-herd in Sweden in 1993. A survey over 10 year (1990-2000) was carried out in order to find the probable cause of the infection. This SPF-herd was started in 1988 and remained closed to new animal material except semen (Artificial Insemination). Serum samples from pigs were retrospectively tested as well as samples from three sows which farrowed after the initial EE outbreak and from their offspring. Their clinical signs were also monitored. Samples were tested for Staphylococcus hyicus (the causative agent of EE), as well as presence of antibody to PCV-2 (interferon-a and interleukin-6). Until Feb. 1993, the SPF-herd was PCV-2 negative. In the time of outbreak, the pigs had varying levels of PCV-2 and piglets showed seroconversion later during 1993. The AI boars from which semen was collected were also sero-positive to PCV-2. S. hyicus was isolated from all pigs prior to the outbreak. One piglet showed clinical signs of EE and 14 others had IFN-a in their serum, an indicator of viral activity. Based on the results of the study, it was concluded that the introduction of PCV-2 was a predisposing factor initiating EE skin lesions and reproductive disturbance.

First report of post-weaning multisystemic wasting syndrome and porcine dermatitis and nephropathy syndrome in pigs in Greece
SAOULIDIS K, KYRIAKIS SC, KENNEDY S, LEKKAS S, MILIOTIS CC, ALLAN G, BALKAMOS GC, PAPOUTSIS PA
J Vet Med B Infect Dis Vet P 2002 49: 202-205
The first cases of PMWS and PDNS associated to PCV-2 in Greece are reported in this paper, with a detailed description of characteristic clinical signs, post-mortem and histopathological findings.

Detection of porcine circovirus 2 (PCV-2) DNA by nested PCR from formalin-fixed tissues of post-weaning multisystemic wasting syndrome (PMWS) pigs in Thailand
KIATIPATTANASAKULBANLUNARA W, TANTILERTCHAROEN R, SUZUKI K, ALBARENQUE SM, THANAWONGNUWECH R, NAKAYAMA H, DOI K
J Vet Med Sci 2002 64: 449-452
Detection of PCV-2 in 16 formalin-fixed paraffin-embedded (FFPE) or formaline-fixed (FF) tissues from PMWS pigs was performed by a first PCR amplification and by the second nested PCR in Thailand as part of a retrospective study (tissues dating from 1993-2000). The second technique was the most sensitive one to detect the virus in all FFPE and FF samples from all pigs with PMWS.

Porcine dermatitis and nephropathy syndrome in Japan
ABE T, YAMADA M, HARITANI M, TANIMURA N, KIMURA KM, KAWASHIMA K
Vet Rec 2002 150: 87-88
A detailed account of the first case of PDNS in Japan, with description of macroscopical and microscopical lesions is given in this paper.