A method to detect bovine viral diarrhea virus contamination in cell cultures using immunoperoxidase staining

Failure to Detect Bovine Viral Diarrhea Virus in Necropsied Farm-Raised White-Tailed Deer (Odocoileus Virginianus) in Pennsylvania

Between January 1 and December 31, 2005 gross and histologic examinations were performed on carcasses of 61 farm-raised white-tailed deer originating from Pennsylvania. Single-tube real-time reverse transcription polymerase chain reaction (real-time RT-PCR) for the detection of bovine viral diarrhea virus type 1 (BVDV-1) and type 2 (BVDV-2) was performed on each animal. Virus isolation was performed on tissue samples from 25 of 61 animals. Immunohistochemical (IHC) staining of ear-notch skin to identify BVDV antigen was performed on each animal. All tissues samples tested negative for both BVDV-1 and BVDV-2 by real-time RT-PCR, virus isolation, and IHC. Gross or histopathologic lesions suggestive of BVDV infection were not detected. Results of this study suggest that BVD is not a common cause of mortality in farm-raised white-tailed deer in Pennsylvania.

Frequent presence of hepaci and pegiviruses in commercial equine serum pools

Novel viruses belonging to the genera Hepacivirus and Pegivirus have recently been discovered in horses and other animal species. Viral genomes of non-primate hepaciviruses (NPHV), equine pegivirus 1 (EPgV 1) and Theiler's disease associated virus (TDAV) were detected in a horse serum routinely used for cell culture propagation in our laboratory. Therefore, a study was carried out to further investigate the presence of these human Hepatitis C virus (HCV) related viruses in equine serum based products used in veterinary medicine and for research and to characterize the viral genomes. Without exception all commercially available equine sera purchased for cell culture propagation (n=6) were tested positive for NPHV, EPgV 1 or TDAV genomes by qRT-PCR. Molecular analyses of one single commercial horse serum from Europe confirmed multiple viral genomes, including two TDAV genomes significantly different from the only published TDAV sequence. Furthermore, multiple batches of horse serum pools (n=35) collected for manufacturing of biological products turned out to be positive for NPHV and EPgV 1 genomes. Nevertheless, the final commercial products (n=9) were exclusively tested qRT-PCR negative. Field samples (n=119) obtained from two premises located in the same region as the donor horses were analyzed, demonstrating the frequent presence of NPHV and EPgV 1, but the absence of TDAV genomes. The presence of NPHV, EPgV 1 and TDAV in commercial equine sera and serum based products could have considerable consequences for biosecurity and may also bias the outcome of research studies conducted with related viruses.

Single-tube single-enzyme reverse transcriptase PCR assay for detection of bovine viral diarrhea virus in pooled bovine serum

A reverse transcriptase PCR (RT-PCR) was developed for use as a diagnostic screening test for the detection of bovine viral diarrhea virus (BVDV) in pooled bovine serum samples. Individual serum samples from 60 dairy cattle herds located in Pennsylvania were evaluated by the microplate virus isolation method, and pooled sera were analyzed by RT-PCR. RT-PCR was sensitive and specific and detected a single viremic serum sample in up to 100 pooled serum samples. RT-PCR analysis of pooled sera provides a rapid and cost-effective method for the screening of cattle herds for the presence of animals persistently infected with BVDV.

Production and evaluation criteria of specific monoclonal antibodies to the hemagglutinin of the H7N2 subtype of avian influenza virus

To enhance the rapidity in diagnosing the spread of avian influenza virus (AIV) in chicken layer flocks, studies were initiated to develop more sensitive and specific immunological and molecular methods for the detection of AIV. In this study, the purification of the hemagglutinin protein (H) from field isolates of H7N2, the production of monoclonal antibodies (MAbs), and their evaluation as diagnostic reagents are reported. Hybridomas were generated by fusion of SP2/0-Ag14 myelomas and spleen cells from immunized mice. Hybridomas secreting antibodies specific for the H protein were assayed by an ELISA and cloned using limiting dilution. The MAbs produced were characterized by hemagglutination inhibition (HI), immunohistochemistry (IHC), indirect fluorescent antibody assay (IFA), Western blots, and IFA flow cytometry using various AIV subtypes (i.e., H4N2, H5N3, H7N2). Of the various MAbs assayed, 6 had consistent and reproducible results in each of the assays used. The results obtained in this investigation enhanced the usage of the MAbs to viral H protein in the surveillance of AIV in chickens.

Neosporosis-associated bovine abortion in Pennsylvania

Neospora caninum was found in fetal tissues of 34 of 688 cases of bovine abortion submitted to the Pennsylvania Animal Diagnostic Laboratory System during the period from May 1994 to November 1996. The aborted fetuses ranged in gestational age from 3 to 8 months. Microscopic lesions consisted primarily of encephalitis and myocarditis. A labeled (strept) avidin-biotin staining procedure using anti-N. caninum polyclonal rabbit serum revealed N. caninum organisms within the fetal brain (27 of 27), heart (10 of 13), placenta (5 of 6), kidney (2 of 2), liver (1 of 4) and skeletal muscle (1 of 1).