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Influenza-like illness was noted in people and pigs in attendance at an Ohio county fair in August 2007. The morbidity rate in swine approached 100% within 1-2 days of initial clinical signs being recognized, and approximately two dozen people developed influenza-like illness. Triple-reassortant swine H1N1 influenza viruses were identified in both pigs and people at the fair. The identified viruses (A/Sw/OH/511445/2007, A/Ohio/01/2007, and A/Ohio/02/2007) were similar to H1N1 swine influenza viruses currently found in the U.S. swine population. This case illustrates the possibility of transmission of swine influenza in settings where there is close human/swine interaction., (© 2012 Blackwell Verlag GmbH.)

A dairy goat operation in Minnesota experienced a sudden, markedly increased mortality among its neonatal goats. Approximately 60 of 130 kids (46%) died. The animals had diarrhea and dyspnea of 1-2 days duration before death. Necropsy of 4 goat kids revealed marked, acute, catarrhal enteritis and fibrinous pleuropneumonia. Mannheimia haemolytica was isolated from the lungs. Basophilic inclusion bodies filling the entire nucleus were present in enterocytes of the ileum of 3 goats. Adenoviral particles were detected in the feces by electron microscopy and adenovirus was subsequently isolated from the intestinal content together with a parvo-like virus (dependovirus). Morphology, physicochemical characteristics, and neutralization tests indicated that the adenovirus resembled ovine adenovirus-2 (OAdV-2). However, the PstI restriction endonuclease pattern produced by the goat adenovirus was distinct from that of OAdV-2. This is the first report of enteritis in goats with an adenovirus antigenically related to OAdV-2 and with a parvo-like dependovirus.

In the last few years, newly recognized paramyxoviruses have been associated with severe disease in several animal species, including swine, as well as in human beings. Recently, a paramyxovirus was isolated from a swine herd in the northcentral United States that experienced an epizootic of respiratory and central nervous system disease. Affected pigs had interstitial pneumonia with necrotizing bronchiolitis and encephalitis characterized by lymphocytic perivasculitis and diffuse gliosis. Germ-free pigs inoculated with this isolate developed mild clinical illness and similar but less severe histopathologic lesions in lungs and brain.

Nasal swabs and lung samples from pigs experimentally infected with H1N1 swine influenza virus (SIV) were examined for the presence of SIV by the indirect fluorescent antibody assay, immunohistochemistry, cell culture virus isolation, egg inoculation, and 2 human enzyme immunoassays (membrane enzyme immunoassay, microwell enzyme immunoassay). Egg inoculation was considered to be the gold standard for assay evaluation. The 2 human enzyme immunoassays (EIA) and egg inoculation agreed 100% for the prechallenge nasal swabs. Agreement on SIV identification in nasal swabs with egg inoculation following challenge was considered to be good to excellent for membrane EIA (kappa = 0.85) and microwell EIA (kappa = 0.86). Agreement on SIV identification in lung tissue with egg inoculation following challenge was good to excellent for membrane EIA (kappa = 0.75), fair for microwell EIA, fluorescent antibody, and cell culture virus isolation (kappa = 0.48, 0.64, 0.62, respectively), and poor for immunohistochemistry (kappa = 0.36). No assay was 100% accurate, including the "gold standard," egg inoculation. In light of this information, it is important to consider clinical signs of disease and a thorough herd history in conjunction with diagnostic results to make a diagnosis of SIV infection.

Bovine viral diarrhea virus (BVDV) infection continues to have a significant impact upon US cattle producers despite the availability of more than 140 federally licensed vaccines. Detection and control is hampered by viral heterogeneity that results in differences in neutralizing epitopes, cytopathology and virulence. Recently it was found that there are two different genotypes, BVDV1 and BVDV2, among BVDV. BVDV2 isolates make up a significant proportion of the BVDV isolated in North America. Serologically BVDV2 viruses can be distinguished from BVDV1 and border disease viruses. Mab binding also distinguishes between BVDV1, BVDV2 and BDV. Like the BVDV1 viruses, BVDV2 viruses may exist as one of two biotypes, cytopathic or noncytopathic, based on their activity in cultured cells. Cytopathogenic effects on cultured cells does not correlate with virulence in vivo, as BVDV2 associated with hemorrhagic syndrome (HS) are noncytopathic. Variation among BVDV1 and BVDV2 in the 5' UTR is similar. Phylogenetic analysis and differences in virulence suggest that BVDV2 are heterogeneous. Symptoms resulting from BVDV2 infections may range from clinically inapparent to clinically severe. Recently, disease outbreaks associated with acute uncomplicated BVDV infection have been reported in the US and Canada. These outbreaks of clinically severe disease, termed HS, were all associated with viruses from the BVDV2 genotype. Not all BVDV2 isolates cause clinically severe disease. Avirulent BVDV2 isolates do exist and may predominate over virulent BVDV2 in nature. When virulent BVDV2 viruses are inoculated into calves they induce a disease characterized by fever, diarrhea, leukopenia, lymphopenia, neutropenia, thrombocytopenia, and death. Infection with avirulent BVDV2 results in a reduction of luekocytes that may be accompanied by a low-grade fever. These viruses do not cause clinical disease or a clinical leukopenia.

The suitability of restriction fragment length polymorphism (RFLP) analysis for differentiating a porcine reproductive and respiratory syndrome virus (PRRSV) vaccine strain from other North American field strains was investigated. Open reading frame 5 nucleotide sequence data of the vaccine virus, its parent strain VR-2332, and 22 other strains of PRRSV included in this study indicated that 3 restriction enzyme gel patterns characterize the vaccine virus and the parent strain genotype. The combined 3 RFLP patterns differentiate the vaccine and parent virus from other PRRSV strains. This test will be a valuable tool in epidemiologic studies and will be useful in identifying individual strains in cases of multistrain PRRSV infections.

Antigenic differences between European and American isolates of porcine reproductive and respiratory syndrome virus (PRRSV) were revealed by serologic analysis of a recombinant protein derived from PRRSV open reading frame 3 (ORF 3). The hydrophilic carboxyterminal 199 amino acids encoded by the ORF 3 of a European (Lelystad) isolate of PRRSV were expressed as a recombinant fusion protein (BP03-P) in a baculovirus gene expression system. Sera from gnotobiotic swine exposed to prototypic reference European and American isolates of PRRSV and sera from conventionally reared European and American swine convalescing from naturally acquired PRRSV infections were used to characterize the BP03-P protein. Sera from gnotobiotic and conventionally reared swine exposed to European isolates of PRRSV were significantly more reactive (P < 0.01) with BP03-P than were the corresponding American PRRSV antisera using the indirect immunoperoxidase monolayer assay (IPMA). Prototypic European, but not American, PRRSV antisera also recognized BP03-P using western immunoblotting and radioimmunoprecipitation assay (RIPA) procedures. However, gnotobiotically derived antiserum to an atypical American-origin PRRSV was reactive with BP03-P by both IPMA and western immunoblot. Despite a predicted potential for N-linked glycosylation, studies with tunicamycin and peptide-N-glycosidase F (PNGase F) indicated that BP03-P was not N-glycosylated in either insect cell cultures or Trichoplusia ni larvae infected with the recombinant baculovirus. Sera from rabbits inoculated with BP03-P failed to neutralize both the European (Lelystad) and American (ATCC VR-2332) reference isolates of PRRSV and did not react by IPMA with PRRSV-infected cell cultures. Taken together, the data suggest that the carboxyterminal portion of PRRSV ORF 3 encodes a non-neutralizing viral peptide that is partially responsible for the serologic differences noted between European and most American isolates of PRRSV.

Four boars intranasally inoculated with porcine reproductive and respiratory syndrome (PRRS) virus were monitored for 56 days after exposure for changes in semen characteristics and for the presence of virus in the semen. Clinically, 2 of 4 boars had mild respiratory signs of 1 day's duration after infection. Changes in appetite, behavior, or libido were not detected. All boars seroconverted on the indirect fluorescent antibody and serum virus neutralization tests by day 14 after inoculation. Virus was isolated from serum between days 7 and 14 after inoculation. During the monitoring period, semen volume decreased and pH correspondingly increased; however, this change began 7 to 10 days prior to infection. Differences in sperm morphologic features, concentration, or motility between the preinfection and postinfection samples were not observed. The PRRS virus was detected in semen at the first collection in each of the 4 boars (ie, 3 or 5 days after challenge exposure). Virus was detected in nearly all semen samples collected from the 4 infected boars through days 13, 25, 27, and 43, respectively. Neither gross nor microscopic lesions attributable to PRRS virus were observed in tissues collected at the termination of the experiment (day 56), and virus isolation results from reproductive tissues were negative.

Seven isolates of the New Jersey serotype of vesicular stomatitis (VSNJ) virus were obtained from pooled specimens of phlebotomine sand flies, Lutzomyia shannoni Dyar, collected on Ossabaw Island, Chatham County, Ga., in 1989 and 1990. Three isolates, including two from males, were obtained from light-trapped sand flies in 1989. Four isolates were obtained from pools of sand flies collected from hollow trees in 1990. Three of the latter pools contained from 4.0 to 4.7 log10 of plaque-forming units of virus per ml, suggesting that the positive flies in these pools had supported VSNJ virus replication. One of these high-titered isolates was obtained from a pool of male sand flies. These data provide further support for the hypotheses that L. shannoni is a biological vector of VSNJ virus at this enzootic focus and that transovarial transmission of the virus occurs in nature.

Four viral contaminants have been routinely detected in unprocessed and commercial lots of fetal bovine serum: bacteriophage, infectious bovine rhinotracheitis, parainfluenza-3 and bovine viral diarrhea virus (BVDV). Of those, BVDV is consistently present in a majority of commercial lots of fetal bovine serum. Methods for BVDV detection and removal are reviewed. The tentative role of an unclassified pestivirus in microcephaly of infants has been reported. Its significance remains uncertain.

The National Veterinary Services Laboratories (NVSL) routinely monitors continuous cell lines (CCL's) used for veterinary biologicals and diagnostic virology. All veterinary biologicals produced in CCL's must follow the master seed concept which limits the use of the master seed CCL to up to 20 passages beyond the passage level characterized and deposited at NVSL. All CLL's are evaluated for the presence of adventitious agents such as mycoplasma, bovine viral diarrhea virus, and other bacteria and viruses. Previously, CCLs were evaluated for tumorigenicity by the Syrian hamster cheek pouch method; however, this procedure has now been eliminated. The adventitious agents most frequently detected in CCL's have been bovine viral diarrhea virus and mycoplasma. Our laboratory has consistently found that the source of bovine viral diarrhea contamination of CCLs has been the use of contaminated fetal bovine cell culture enrichment serum. Gamma irradiation at 2.5-3.5 megarads at -40 degrees C of carefully screened fetal bovine serum has been used in the Diagnostic Virology Laboratory for over 10 years. If the irradiated serum is used at a final concentration of 10 percent, there is no untoward effect on cell susceptibility for virus propagation or cell culture growth. Gamma irradiation has also been demonstrated to be a very efficient inactivator of mycoplasma. Specific conditions utilized by our laboratory to preserve fetal bovine serum cell culture growth factors while eliminating adventitious bovine viral diarrhea virus will be presented.