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J F Ridpath

Publications and source records attributed to J F Ridpath.

At least 19 recordsLinked to original sources
PubMed2006

Detection of viruses: atomic force microscopy and surface enhanced Raman spectroscopy.

This paper demonstrates the capability of atomic force microscopy (AFM) and surface enhanced Raman spectroscopy (SERS) to function effectively as ultra-sensitive readout tools for chip-scale platforms designed for pathogen detection in complex biological media. AFM allows direct (i.e., label-free) visualization and quantification of nanometer-sized viruses captured on a smooth, selective surface. AFM readout led to optimization of a capture substrate for feline calicivirus (FCV), and yielded a limit of detection of 3 x 10(6) FCV/mL. SERS-based detection of FCV, carried out in a sandwich-type assay, requires labelling of the substrate-bound FCV with a selective extrinsic Raman label (ERL). These studies yielded a limit of detection of 1 x 10(6) FCV/mL. The prospects of these two readout methods as additions to the arsenal of tools in bioterrorism prevention are briefly discussed.

Calicivirus, Feline↗
PubMed2005

Characterization of a novel pestivirus originating from a pronghorn antelope.

A unique pestivirus, isolated from a pronghorn antelope (Antilocopra americana), was characterized. Serum neutralization studies suggested that this virus was antigenically related to pestiviruses. Genomic characteristics, unique to pestiviruses, indicated that this virus belongs to the Pestivirus genus. These characteristics included the organization of the 5' untranslated region (5'-UTR), the presence and length of a viral Npro coding region, conservation of cysteine residues in Npro, conservation of predicted amino acid sequences flanking the cleavage sites between viral polypeptides Npro and C and between C and Erns and conservation of predicted hydrophobicity plots of Npro protein. While this data indicated the virus belongs to the Pestivirus genus, phylogenetic analysis in 5'-UTR, Npro and E2 regions suggested that it is the most divergent of the pestiviruses identified to date. This conclusion was also supported by the amino acid identity in coding regions. The corresponding values were much lower for the comparison of pronghorn pestivirus to other pestivirus genotypes than only between previous recognized genotypes. These results suggest the virus isolated from pronghorn antelope represents a new pestivirus genotype. It also represents the only pestivirus genotype first isolated from New World wildlife.

5' Untranslated Regions↗
PubMed2005

Viral antigen distribution in the respiratory tract of cattle persistently infected with bovine viral diarrhea virus subtype 2a.

Tissues were obtained at necropsy from the nasal vestibule, turbinates, nasopharynx, trachea, tracheobronchial bifurcation, and lung from each of 10 clinically healthy calves persistently infected (PI) with bovine viral diarrhea virus (BVDV) serotype 2a. Tissues from the nasal vestibule were obtained by biopsy from five additional PI calves. Formalin-fixed tissues were processed for immunohistochemistry to localize the distribution of BVDV throughout the respiratory tract. Antigen distribution and intensity were subjectively evaluated. Throughout the respiratory tract, mononuclear leukocytes, vascular smooth muscle, and endoneural and perineural cells had BVDV immunoreactivity (BVDV-IR). Multifocally, squamous and ciliated columnar epithelium throughout the respiratory tract contained weak to moderate BVDV antigen. Viral antigen was not seen in goblet cells. BVDV-IR in mixed tubuloalveolar glands of the nasal cavity was weak to strong in serous secretory cells and ductular epithelium. Chondrocytes of the concha often contained BVDV antigen diffusely. Nasal mucus-secreting and tracheobronchial glands multifocally contained weak viral signal. In all cases, alveolar macrophages had moderate to strong BVDV-IR, whereas BVDV-IR in alveolar epithelial cells was weak to moderate. BVDV was present in interalveolar leukocytes and mesenchymal cells. Results indicate that serous secretions of the nasal cavity, productive viral infection of epithelium, and infected leukocytes in respiratory secretions are likely major sources of infectious BVDV from PI calves. The presence of BVDV antigen in respiratory epithelium is, at least, indirect support for the notion that this virus predisposes PI cattle to secondary microbial infections.

Animals↗
PubMed2003

Lesions and tissue distribution of viral antigen in severe acute versus subclinical acute infection with BVDV2.

Differences in the distribution and spread of viral antigen, development of lesions and correlation between presence of viral antigen and lesions were compared between a low and highly virulent strain of BVDV2. Two groups of two-week- to two-month-old colostrum-deprived calves were inoculated intranasally with the naturally occurring low virulent BVDV2 strain 28508-5 or the highly virulent strain 1373. To study the sequence of virus spread and lesion development, calves were necropsied at days three, six, eight-nine and 12 to 14 post inoculation (pi). Viral antigen was detected by the indirect immunoperoxidase method in cryostat sections and lesions were evaluated in H&E-stained paraffin sections. Clinical signs and changes in lymphocyte and thrombocyte numbers confirmed the difference in virulence between the two strains. Both strains showed comparable initial infection and spread at day three pi. At day six pi, they were found widespread in lymphoid tissues and multifocally in intestinal mucosa. Lesions were very mild despite the large amount of antigen in the lymphoid tissues. After day six pi, differences between the low and highly virulent strains became more prominent. The strain of low virulence was cleared from the tissues, but there was a transient phase of depletion. The highly virulent strain continued to spread to different organs and there was severe depletion of lymphoid tissues without recovery.

Animals↗
PubMed2001

Recombination with a cellular mRNA encoding a novel DnaJ protein results in biotype conversion in genotype 2 bovine viral diarrhea viruses.

Bovine viral diarrhea viruses (BVDV) exist as two biotypes, cytopathic and noncytopathic, based on their ability to produce cytopathology in cultured cells. Cytopathic viruses arise from noncytopathic viruses following genetic alteration (insertions, duplications, rearrangements) within the region encoding the NS2/3 protein. In BVDV genotype 2, the majority of biotype conversions result from the integration of a cellular mRNA into the genomic RNA of a noncytopathic virus within the NS2/3 coding region. The translation of the cellular sequences during viral replication results in the proteolytic cleavage of the nonstructural protein NS2/3 to the NS2 and NS3 proteins with the appearance of the cytopathic phenotype. Here, these cellular sequences were identified as a portion of a cellular mRNA encoding a novel DnaJ protein (bDnaJ1). The 60 amino acid J-domain was identified near the C-terminus of the protein. Potential nuclear localization, farnesylation and hydrophobic transmembrane domains were also identified. Reverse transcription-PCR analysis of the expression of bDnaJ1 in bovine tissues showed that it was expressed in all tissues examined, and additionally, there may be alternate splicing of the transcript, yielding a second form of the bDnaJ1 protein. Northern blot analysis of mock and BVDV2 infected cells indicated that infection by noncytopathic BVDV2 altered the expression level of a bDnaJ1-hybridizing transcript. The increase in expression may represent a stress response to the infection by noncytopathic BVDV.

Amino Acid Sequence↗
PubMed2000

Phylogenetic, antigenic and clinical characterization of type 2 BVDV from North America.

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.

Animals↗
PubMed2000

Morphologic lesions in type 2 BVDV infections experimentally induced by strain BVDV2-1373 recovered from a field case.

Widespread outbreaks of severe acute BVDV, some associated with hemorrhagic syndrome (HS), were reported in Quebec and Ontario in 1993. These outbreaks caused significant economic hardship in infected herds. In the Ontario outbreak 150 dairy, 600 beef and 100 milk and grain fed veal herds were affected with losses estimated at $40000-$10000 per herd in lost animals, milk production, abortions and genetics. Fever, pneumonia, diarrhea, and sudden death occurred in all age groups of cattle. Abortions were frequently observed in pregnant cattle. The viruses associated with this outbreak were determined to be noncytopathic BVDV from the type 2 genotype. All BVDV2 associated with these outbreaks were noncytopathic. One of the viruses isolated from the Ontario outbreak, BVDV2-1373, was used to experimentally induce HS in 5-6 weeks old colostrum deprived, seronegative calves. All animals developed leukopenia and thrombocytopenia within 6-10 days with some developing bloody diarrhea and becoming moribund. Animals were killed for necropsy between 6 and 11 days postinfection. Histopathologically lesions were similar, but more severe, to those seen early on (within first 9 days after superinfection) in animals with experimentally induced mucosal disease (MD). There were no erosions and ulcerations present in the upper digestive tract. In hemorrhages in the mucosa, virus antigen (VA) was present in macrophages of both the lamina propria and the submucosa and in basal epithelial cells. Cells containing VA were vacuolated and separated from each other. The most severe lesions observed in the digestive tract were in the Peyers patches and were characterized by depletion of lymphocytes and proliferation of crypt cells resulting in crypthyperplasia. Apoptotic cells were present in crypts and areas of lymph follicles where viral antigen was detected. Out of the six animals, VA was present in four animals in the pancreas, three animals in the pituitary and in two animals in the adrenal glands. The results suggest that the pathology resulting from acute infection with a highly virulent noncytopathic BVDV2 differs from the pathology observed in classic mucosal disease.

Animals↗
PubMed2000

Clinical, pathological and antigenic aspects of bovine viral diarrhea virus (BVDV) type 2 isolates identified in Brazil.

Nucleotide sequencing and phylogenetic analysis of Brazilian bovine viral diarrhea virus (BVDV) field isolates identified four viruses belonging to the genotype 2. Comparison of 5' UTR sequences from these isolates to those of North American BVDV type 2 revealed genomic variations that correlated with the geographic origins of the isolates. Two of the Brazilian type 2 viruses were isolated from clinical cases of gastroenteric/respiratory disease and two were isolated from healthy bovine fetuses. The clinical cases affected young animals (8- and 18-months-old) and were characterized by diarrhea, respiratory signs, extensive oral and digestive tract erosions, conjunctival and vulvar congestion, occasional digestive bleeding and vulvar and heart petechial hemorrhage. Antigenic analysis of these isolates with a panel of 10 monoclonal antibodies revealed marked antigenic differences in the major envelope glycoprotein, gp53/E2, compared to standard laboratory and vaccine BVDV strains. In addition, virus-specific antisera raised to Brazilian BVDV type 2 viruses displayed very low serological cross-reactivity with standard BVDV type 1 strains. Differences up to 64-fold in cross-neutralization titers were observed between BVDV type 1 and Brazilian BVDV type 2 isolates. The identification of BVDV type 2 among Brazilian cattle may have important implications for epidemiological studies, diagnostic and immunization strategies. Furthermore, the low neutralizing activity of BVDV type 1 antisera against the recently identified Brazilian BVDV type 2 isolates raises the question about the degree of protection conferred by BVDV vaccines, most of them based on a single type 1 strain.

Animals↗
PubMed2000

Bovine viral diarrhea virus cytopathic and noncytopathic biotypes and type 1 and 2 genotypes in diagnostic laboratory accessions: clinical and necropsy samples from cattle.

One hundred three bovine samples submitted to the Oklahoma Animal Disease Diagnostic Laboratory (OADDL) that were positive for bovine viral diarrhea virus (BVDV) were typed by a nested reverse transcription-polymerase chain reaction for BVDV genotypes. These BVDV samples included supernatants from virus isolation (79), serums (17), and buffy coats (7). The biotype, cytopathic (CP) or noncytopathic (NCP), was determined by cell culture virus isolation. Twenty-eight of 103 samples were submitted for herd screening for BVDV, 32 from OADDL necropsy cases, and 43 from live cattle with varied clinical conditions. Two samples contained 2 bands indicating presence of both BVDV types 1 and 2. Of the 105 BVDV samples, 26 were type 1 CP strains (24.8%), 38 were type 1 NCP strains (36.2%), 10 were type 2 CP strains (9.5%), and 31 were type 2 NCP strains (29.5%). From the 105 BVDV isolates, NCP biotypes were isolated more frequently (69, 65.7%) than CP biotypes (36, 34.3%), and type 1 genotypes were more frequently isolated (64, 61.00%) than type 2 genotypes (41, 39.0%). The NCP strains were more common than CP in herd screening samples. Cattle with respiratory disease history at time of sampling had more NCP than CP biotypes and more type 1 than type 2 genotypes. Of the necropsy cases, more were type 1 than type 2 genotypes for the respiratory cases with fibrinous pneumonia, more were type 1 than type 2 genotypes in cattle with enteritis/colitis without systemic lesions, and more were CP than NCP biotypes in cattle with enteritis/colitis with systemic lesions. No CP biotype was isolated from serum samples.

Animals↗
PubMed1999

Nested reverse transcriptase-polymerase chain reaction (RT-PCR) for typing ruminant pestiviruses: bovine viral diarrhea viruses and border disease virus.

A nested reverse transcription (RT) polymerase chain reaction (PCR) assay was evaluated for differentiating reference bovine viral diarrhea virus (BVDV) strains, BVDV from diagnostic accessions, modified-live virus (MLV) BVDV strains in bovine viral vaccines, and a reference border disease virus (BDV). The detection level of this assay was compared to viral infection in cell culture. The PCR assay was used to distinguish 3 ruminant pestiviruses, types 1 and 2 BVDV, and type 3 BDV. The consensus (first) PCR assay detected all 3 ruminant pestiviruses, a result of the shared sequence homology. The consensus PCR product was subjected to a second (nested) PCR which used type-specific primers. The nested PCR was able to differentiate the 3 ruminant pestiviruses. Viral stocks of BVDV were diluted 10-fold and processed for the 2-step PCR assay. The sensitivity of this 2-step PCR assay was compared to viral infectivity in cell culture based on identical volumes of the system tested (cell culture assay and processing for RNA). The RT-PCR type-specific assay differentiated BVDV laboratory reference strains (12), diagnostic laboratory isolates (15), 2 MLV BVDV vaccine strains, and a BDV strain. The 30 ruminant pestiviruses typed included: (1) 27 reference strains and diagnostic laboratory isolates; 18 cytopathic (CP) type 1 strains, 3 CP type 2 strains, 3 noncytopathic (NCP) type 1 strains, and 3 NCP type 2 strains; (2) 2 MLV strains, type 1; and (3) 1 CP BDV type 3. The PCR assay had a detection limit of 10 TCID50/0.025 mL of virus when 3 separate BVDV were tested. This 2 step RT-PCR assay would be useful for the typing of ruminant pestiviruses, particularly BVDV isolates from the diagnostic laboratory.

Animals↗
PubMed1998

Differentiation of types 1a, 1b and 2 bovine viral diarrhoea virus (BVDV) by PCR.

There are two genotypes among bovine viral diarrhoea viruses (BVDV), BVDV1 and BVDV2. Within the BVDV1 genotype there are two distinct subgenotypes, BVD1a and BVD1b. Serology and monoclonal antibody binding are used to differentiate BVDV from classical swine fever virus (CSFV) and border disease virus (BDV), the other members of the Pestivirus genus. These techniques are less useful in the differentiation and segregation of viruses within the BVDV species. In this study, differential polymerase chain reaction (PCR) amplification has been evaluated as a tool for segregating BVDV isolates into genotypes and subgenotypes. Polymerase chain reaction primers were selected based on the comparison of 5' untranslated region sequences from CSVF, BDV, BVDV1a, BVDV1b and BVDV2. Differential PCR tests were validated using 345 viruses isolated from cattle and small ruminants that had previously been segregated into genotypes and subgenotypes. There was 100% correlation between segregation by differential PCR and the previous segregation of these viral isolates.

Animals↗
PubMed1998

Mapping of a type 1-specific and a type-common epitope on the E2 (gp53) protein of bovine viral diarrhea virus with neutralization escape mutants.

Bovine viral diarrhoea viruses (BVDV) have recently been segregated into two genotypes, BVDV 1 and BVDV 2. However, the antigenic differences and similarities of BVDV 1 and BVDV 2 remain poorly defined. In this study, the E2 epitopes of two neutralizing monoclonal antibodies (mAbs) produced against an isolate of BVDV 1 were mapped. The mAb 157, previously determined to be broadly cross-reactive to BVDV, was discovered to be BVDV 1-specific, whereas mAb 348 bound to and neutralized BVDV 2. Both mAbs bound to epitopes within the first 192 amino acids of the E2 protein as determined by reactions with a C-terminally truncated E2. To identify critical amino acids affecting these epitopes, mAb escape mutants were selected for sequencing from BVDV 1 and BVDV 2 strains with different (wild-type) mAb binding phenotypes. In addition, the E2 gene of several BVDV were sequenced and the sequences were compared with amino acid changes in mutant viruses. Single nucleotide changes in escape mutants selected with mAb 157 resulted in deduced amino acid changes at E2 positions 9, 32 or 72. Amino acid changes at position 72 also affected the epitope of mAb 348. Alignment of E2 nucleotide sequences revealed that BVDV 2 are missing six nucleotides encoding the equivalent of amino acids 31 and 32 of BVDV 1 and thus, this difference can account for the BVDV 1-specificity of mAb 157. Single nucleotide mutations in mAb 348 escape mutants of BVDV 1 and BVDV 2 resulted in changes in 3 amino acids in the previously described immunodominant 71-74 region (Virology 190, 763-772). A fourth amino acid change observed in a mutant of BVDV 2 extended this region to position 77. Thus, the amino acid changes affecting the conserved epitope of mAb 348 occurred in a short spatial array over only seven amino acids, unlike the described composite epitopes previously mapped to this region.

Amino Acid Sequence↗
PubMed1998

Insertion of a bovine SMT3B gene in NS4B and duplication of NS3 in a bovine viral diarrhea virus genome correlate with the cytopathogenicity of the virus.

Bovine viral diarrhea virus (BVDV) infection in cattle can lead to the development of a fatal syndrome called mucosal disease (MD). The induction of MD requires co-existence of two biotypes of BVDV: cytopathic (cp) and non-cytopathic (ncp). Studies have shown that in some cases, cp viruses are generated from ncp viruses by cellular gene insertions, duplications or rearrangements in the viral genome. Cellular ubiquitin gene is the most frequently reported insert in BVDV 1. Here we report the finding of a novel cellular gene insertion (termed cSNCINS) in the NS4B gene accompanied by the duplication of NS3 in a cpBVDV genome. The amino acid sequence of the insert is identical to that of the human SMT3B protein and is 98% similar to that of the human SMT3A protein. Both SMT3B and SMT3A proteins are homologues of the yeast SMT3 protein. The cSNCINS protein is encoded by an open reading frame located on a 1150-bp bovine endometrial cDNA fragment. Our results indicate that the cSNCINS is a bovine homologue of the human SMT3B gene and that insertion of the BSMT3B gene together with duplication of NS3 in the viral genome may account for the cytopathogenicity of this virus.

Amino Acid Sequence↗
PubMed1998

Prevalence of bovine viral diarrhea virus genotypes and antibody against those viral genotypes in fetal bovine serum.

One thousand lots of pooled fetal bovine serum (FBS) were tested for contamination with bovine viral diarrhea virus (BVDV) and/or for contamination with neutralizing antibody against BVDV. Noncytopathic or cytopathic BVDV was isolated from 203 lots of FBS. Analysis of the viral isolates identified 115 type 1 and 65 type 2 BVDV isolates. An additional 23 virus isolates were mixtures of > or = 2 BVDV isolates and were not classified to viral genotype. Further characterization of the type 1 viruses identified 51 subgenotype 1a and 64 subgenotype 1b BVDV isolates. Viral neutralizing antibody was detected in 113 lots of FBS. Differential viral neutralization indicated that type 1 BVDV induced the antibody detected in 48 lots of FBS and type 2 BVDV induced the antibody detected in 16 lots of FBS.

Animals↗
PubMed1998

Use of polymerase chain reaction to simultaneously detect and type bovine viral diarrhoea viruses isolated from clinical specimens.

The techniques of indirect immunofluorescence (IF), immuno-peroxidase (IP) staining and the one-step reverse transcriptase polymerase chain reaction (RT-PCR) were compared for detection of 102 isolates of bovine viral diarrhoea virus (BVDV) in infected cell cultures. The BVDV was obtained from bovine clinical specimens, including sera, buffy coats and tissues, submitted from farms located in the States of Iowa and Wisconsin, United States of America. The IF technique detected 88/102 (86.3%) of the viral isolates, whereas IP staining detected an additional 4 isolates (92/102; 90%). The one-step RT-PCR using primers derived from the 5' untranslated region of the BVDV genome detected 102/102 (100%) of the BVDV isolates. A second-round PCR utilising another pair of PCR primers from the 5' untranslated region, allowed rapid genotyping of BVDV. The procedure used showed that the PCR assay based on the 5' untranslated region of the virus genome is the most sensitive indicator for BVDV detection in cell culture, and is also of considerable epidemiological importance since it allowed rapid genotyping of BVDV isolated from clinical specimens. In addition to detection and genotyping of BVDV isolated from clinical specimens, the RT-PCR procedure can be used for routine screening of locally produced and imported biologicals for BVDV contamination. However, the procedure requires further refinement to enable direct application on the clinical specimen.

Animals↗
PubMed1998

Specificity and duration of neutralizing antibodies induced in healthy cattle after administration of a modified-live virus vaccine against bovine viral diarrhea.

OBJECTIVE: To determine the duration for cross-neutralizing antibodies stimulated by administration of a single dose of a modified-live vaccine against bovine viral diarrhea virus (BVDV) to seronegative cattle. ANIMALS: 23 Angus cows seronegative to BVDV. PROCEDURE: Cows were randomly assigned to control (unvaccinated) or test (vaccinated) groups. Eighteen BVDV-seronegative Angus cattle were vaccinated via IM injection with a modified-live BVDV (NADL strain) vaccine and commingled with 5 unvaccinated seronegative cows. Serum was obtained from the cows before vaccination, on the day of vaccination, and 1.5, 3, 6, 9, 12, and 18 months after vaccination. Serum neutralizing antibody tests were performed on samples obtained at each point after vaccination, using a panel of 12 strains of BVDV that, on the basis of reactivity with monoclonal antibodies, were identified as heterologous. RESULTS: Antibodies against all 12 strains of BVDV (which we tested) were detected by use of viral neutralization testing in samples obtained from vaccinated cattle 18 months after vaccination; however, concentration of antibody for some of the strains was low. Nonvaccinated cattle remained seronegative throughout the 18-month study period. CLINICAL IMPLICATIONS: Analysis of these data indicated that modified-live BVDV vaccines could stimulate an antibody response in seronegative cows that was detectable for at least 18 months after vaccination. These antibodies were able to cross neutralize 12 antigenically diverse strains of BVDV.

Animals↗
PubMed1998

Protection of pregnant cattle and their fetuses against infection with bovine viral diarrhea virus type 1 by use of a modified-live virus vaccine.

OBJECTIVE: To determine efficacy of a vaccine containing modified-live bovine viral diarrhea virus (BVDV) type 1 for protecting pregnant cows and their fetuses against virulent heterologous BVDV type 1. DESIGN: Randomized controlled cohort study. ANIMALS: 18 yearling beef heifers seronegative for BVDV and negative when tested for BVDV by virus isolation. PROCEDURE: Cattle were randomly assigned to control (unvaccinated; n = 6) or vaccinated (12) groups. Vaccinated heifers were given a combination vaccine containing modified-live BVDV type 1 comprising a cytopathic (NADL) strain. All 18 heifers were then bred and challenge-exposed between 70 and 75 days of gestation with BVDV type 1, administered intranasally. Cattle were monitored, and infection status of offspring was determined after parturition. Antibody concentrations of vaccinated and control heifers were also monitored. RESULTS: All 6 calves from control heifers had positive results on multiple virus isolation tests and were considered persistently infected. In comparison, only 2 calves from vaccinated cows had positive results on virus isolation tests and were considered persistently infected. One vaccinated heifer aborted, but the fetus was not persistently infected, and the abortion was not attributed to BVDV infection. CLINICAL IMPLICATIONS: Analysis of these data indicated that a single dose of a modified-live NADL-derived BVDV type 1 vaccine will confer protection to dams and their fetuses against challenge-exposure to heterologous BVDV type 1 organisms.

Animals↗