Search PubMed⌕ Search

Biomedical subjects

S R Bolin

Publications and source records attributed to S R Bolin.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1997

Comparison of the complete genomic sequence of the border disease virus, BD31, to other pestiviruses.

The genus Pestivirus is composed of hog cholera virus (HCV) [also known as classical swine fever virus (CSFV)], bovine viral diarrhea virus (BVDV), and border disease virus (BDV). Complete sequences have been published for HCV (or CSFV) and the two genotypes of BVDV (BVDV1 and BVDV2). In this study the complete sequence of the border disease virus (BDV), BD31, was determined. BD31 was isolated from a lamb with hairy shaker syndrome and is the BDV type virus offered by ATCC (ATCC VR-996). The genome was 12268 nucleotides long and had a single large open reading frame (ORF) beginning at nucleotide 357 and ending at nucleotide 12045. The sequence identity of the predicted amino acid sequence of BD31 and other published pestivirus sequences varied from 71% to 78%. Phylogenetic analysis of available complete genomic sequences segregated pestiviruses into two branches. One branch contained BD31 and HCV (or CSFV) isolates while the other branch contained BVDV1 and BVDV2 isolates. Pestiviruses from the same branch were similar in the length of the 5' and 3' untranslated regions (UTR). When complete genomic sequences were compared among BD31, HCV (or CSFV), BVDV1 and BVDV2, the highest sequence identity was observed in the 5' UTR. Within the ORF, the highest sequence identity was observed in the genomic region coding for the nonstructural viral polypeptide p80.

Amino Acid Sequence↗
PubMed1997

Neutralizing antibodies to type 1 and 2 bovine viral diarrhea viruses: detection by inhibition of viral cytopathology and infectivity by immunoperoxidase assay.

Neutralizing antibodies to type 1 and 2 bovine viral diarrhea virus (BVDV) strains were measured by a microtiter virus neutralization test (MVNT) in cell culture. Antibodies (neutralizing) were detected by inhibition of viral infectivity, by the absence of viral cytopathology for cytopathic strains, or by immunoperoxidase staining for noncytopathic strains. The immunoperoxidase-stained monolayers could be detected without the aid of light microscopy. Twenty BVDV strains were used as challenge viruses in the in vitro MVNT, including 14 type 1 and 6 type 2 strains. Representative noncytopathic and cytopathic strains of both types were used. Positive control serum samples available for diagnostic testing contained both type 1 and type 2 BVDV antibodies. There did not appear to be major differences in antibody titers among the respective type strains, regardless of biotype (cytopathic or noncytopathic). In a study with sera from calves receiving a modified live virus or inactivated BVDV vaccine, the calves receiving type 1 strains responded with higher antibody titers to type 1 strains than to type 2 strains.

Animals↗
PubMed1996

Glycoprotein E2 of bovine viral diarrhea virus expressed in insect cells provides calves limited protection from systemic infection and disease.

Calves were vaccinated with a C-terminally truncated baculovirus expression product of E2 from the Singer strain of bovine viral diarrhea virus. The expressed E2 was glycosylated and retained antigenic authenticity. After induction of viral neutralizing antibody, the calves were challenge exposed with either the homologous Singer strain of virus or with the heterologous 890 strain of virus. Vaccine-induced antibody titer of > or = 2 protected calves from clinical signs of disease induced by homologous viral challenge exposure. An antibody titer of > or = 512 reduced replication of homologous challenge virus to a level which did not induce an appreciable increase in serologic titer of viral neutralizing antibody. Vaccine-induced antibody titer of < or = 4096 did not protect calves from systemic spread of virus or from disease after challenge exposure with heterologous bovine viral diarrhea virus.

Animals↗
PubMed1995

The genomic sequence of a virulent bovine viral diarrhea virus (BVDV) from the type 2 genotype: detection of a large genomic insertion in a noncytopathic BVDV.

A second genotype of bovine viral diarrhea virus, BVDV genotype 2 or BVDV 2, has been identified based on phylogenic analysis of sequences from the 5' untranslated region of the viral RNA. In this study, we derived the complete nucleic acid sequence of a virulent BVDV 2 virus, BVDV2-890, isolated from an animal that died of an acute uncomplicated BVDV infection. BVDV2-890 is noncytopathic in cell culture and does not produce a p80 viral polypeptide. The ORF of BVDV2-890 is 11,922 nucleotide bases long and codes for 3973 amino acids. In comparison, the ORFs of other noncytopathic pestiviruses are shorter by about 250 nucleotides. The sequence identity at the amino acid level, between BVDV2-890 and published sequences for other pestiviruses, is 74% or less. The most conserved nucleotide and amino acid sequences between BVDV2-890 and other pestiviruses are located in the region coding for the nonstructural protein p80. The least conserved are in the regions coding for the structural polypeptide gp53 and nonstructural polypeptides p54 and p58. The larger size of the BVDV2-890 ORF is due to a 228-nucleotide insertion in the portion of the genome coding for the viral polypeptide p54. The location of this insertion was upstream from those reported in cytopathic pestiviruses. This insertion was not characteristic of all of the BVDV 2 viruses or all of the virulent BVDV 2 viruses.

Amino Acid Sequence↗
PubMed1995

Delayed onset postvaccinal mucosal disease as a result of genetic recombination between genotype 1 and genotype 2 BVDV.

Bovine viral diarrhea viruses (BVDV) are segregated into two genotypes, BVDV 1 and BVDV 2. Viruses within both genotypes may exist as one of two biotypes, cytopathic or noncytopathic. A highly fatal form of BVDV termed mucosal disease (MD) occurs when an animal persistently infected with noncytopathic BVDV becomes superinfected with cytopathic BVDV. In this study, we characterized a noncytopathic (BVDV2-125nc)/cytopathic (BVDV2-125c) viral pair isolated from an animal that died of MD 3 months after vaccination with modified-live BVDV1-NADL. In comparison to BVDV2-125nc, BVDV2-125c contained a 366-nucleotide insertion. The insertion was in the correct reading frame for the large open reading frame of the BVDV genome and occurred in the portion of the genome that codes for the p125 viral polypeptide. There was a 99% identity between the inserted sequences found in BVDV2-125c and sequences from the vaccine virus BVDV1-NADL. These data suggest that MD was induced after a recombination between noncytopathic BVD2-125nc and cytopathic vaccine virus BVDV1-NADL created the cytopathic virus BVDV2-125c.

Amino Acid Sequence↗
PubMed1995

The pathogenesis of mucosal disease.

The pathogenesis of MD is complex and remains somewhat obscure. Clearly, the disease occurs in cattle persistently infected with noncytopathic BVDV. It also is clear that cytopathic BVDV is associated with MD, and is the likely trigger of the cellular destruction that leads to clinical disease. Whether the cellular destruction is attributable directly to the cytopathic virus, or occurs as the result of other mechanisms remains unclear. Although immunotolerance is involved in MD, it can be broken and its role in the disease process needs further research. It is logical, and well supported by research, that noncytopathic BVDV is the source of cytopathic BVDV. It also is likely that most outbreaks of MD are the result of a spontaneous mutation of noncytopathic to cytopathic virus within a PI animal. Antigenic homology between viruses would be expected in those outbreaks. MD also occurs when PI cattle are exposed with a cytopathic BVDV that is antigenically heterologous with the resident noncytopathic BVDV. In those situations, it may be a race between the cytopathic virus and the immune system.

Acute Disease↗
PubMed1995

Control of bovine viral diarrhea infection by use of vaccination.

Vaccination with either inactivated or modified live virus vaccines is beneficial for control of BVD in cattle. The advantages and/or disadvantages of each type of vaccine often influence vaccine selection. The frequency of vaccination depends on the herd management system, regional prevalence of BVDV, and required duration of protection. Vaccines for BVD likely will change in content as knowledge of BVDV increases and as new technologies are adapted for vaccine production.

Animals↗
PubMed1995

Assessment of protection from systemic infection or disease afforded by low to intermediate titers of passively acquired neutralizing antibody against bovine viral diarrhea virus in calves.

Colostrum-deprived calves (n = 24) were fed various amounts of colostrum, colostrum substitute, or milk replacer to establish a range in titer of passively acquired viral neutralizing antibody in serum. The calves were then challenge exposed intranasally with a virulent, noncytopathic bovine viral diarrhea virus (BVDV-890). After viral challenge exposure, calves were monitored for fever, leukopenia, thrombocytopenia, and diarrhea. In addition, viral isolation and viral titration were performed on specimens of nasal secretions, buffy coat cells, and serum obtained from the calves. Fever and systemic spread of virus were detected in calves that had viral neutralizing titer of 256 or lower. Calves that had viral neutralizing titer lower than 16 developed severe clinical disease manifested by fever, leukopenia, thrombocytopenia, and diarrhea. Severity and duration of signs of disease decreased as titers of passively acquired viral neutralizing antibody increased. These results indicate that low to intermediate titers of passively acquired viral neutralizing antibody were not sufficient to fully protect calves from virulent bovine viral diarrhea virus.

Animals↗
PubMed1994

Segregation of bovine viral diarrhea virus into genotypes.

Isolates of bovine viral diarrhea virus (BVDV) were segregated into two groups based on comparison of sequences from the 5' untranslated region (UTR) of the viral genome. Phylogenic analysis suggested that these groups, termed BVDV I and BVDV II, are as different from each other as reference BVDV (BVDV-NADL, BVDV-SD-1, BVDV-Osloss) are from hog cholera virus. Polymerase chain reaction (PCR) tests, based on the 5' untranslated region and the genomic region coding for the p125 polypeptide, were designed to differentiate between BVDV I and BVDV II. Using these tests, 76 of 140 isolates of BVDV were identified as BVDV II. Antigenic and pathologic differences were noted between BVDV I and BVDV II viruses. Among BVDV I were viruses commonly used in vaccine production, diagnostic tests, and research. BVDV II was isolated predominantly from fetal bovine sera, persistently infected calves born to dams vaccinated against BVDV, and cattle that had died from an acute form of BVDV termed hemorrhagic syndrome.

Amino Acid Sequence↗
PubMed1994

Detection of a cell line contaminated with hog cholera virus.

Cell lines from the repository of the American Type Culture Collection were examined for possible contamination with bovine viral diarrhea virus. During testing, hog cholera virus (HCV) was detected in the IB-RS-2 D10 porcine kidney cell line. This variant of HCV was avirulent for pigs and seldom induced detectable concentrations of antibody against reference viruses (HCV-Ames or bovine viral diarrhea virus-NY1) in serum of inoculated pigs. Additionally, this variant of HCV did not confer protection to pigs against virulent HCV. The contaminated cell line had been distributed to > 20 laboratories in the United States. The cell line was not used in field studies and has been destroyed.

Animals↗
PubMed1994

Natural recombination in bovine viral diarrhea viruses.

BVDV isolates exist as two biotypes differentiated at the molecular level by production of a p80 polypeptide. Insertions consisting of host cell sequences and/or duplicated and rearranged viral sequences have been observed in the portion of the genome coding for the p80 polypeptide in some, but not all, cytopathic BVDV. The significance of these insertions to biotypic expression has yet to be demonstrated. It has been hypothesized that recombination results in the production of the p80 polypeptide by introduction of a cleavage site into a precursor polypeptide or the introduction of a second copy of the p80 gene. Because inserts have not been identified in all cytopathic BVDV examined, it appears that recombination may not be the only mechanism involved in biotypic determination.

Animals↗
PubMed1994

Survey of cell lines in the American Type Culture Collection for bovine viral diarrhea virus.

Cell lines originating from cattle, sheep, goat, deer, bison, swine, rabbit, hamster, cat, dog, monkey, human, and mosquito were obtained from the American Type Culture Collection and tested for contamination with bovine viral diarrhea virus (BVDV). Immunocytochemical procedures and polymerase chain reaction (PCR) amplification were used to detect viral antigen or viral RNA in 13 of 41 cell lines. The results of these procedures correlated exactly. Cell lines derived from cattle, sheep, goat, deer, bison, rabbit, and domestic cat were found contaminated with BVDV. Attempts were made to experimentally infect 14 swine, rabbit, hamster, cat, dog, monkey, and human cell lines that had been found free of virus. All swine cell lines, and most rabbit and cat cell lines, became infected with BVDV. Hamster, human, dog, and certain rabbit and cat cells were refractory to BVDV infection. Experimental infection of monkey cells produced variable results.

Animals↗
PubMed1994

Monoclonal antibodies to bovine viral diarrhea virus: cross-reactivities to field isolates and hog cholera virus strains.

Monoclonal antibodies to bovine viral diarrhea virus (BVDV) were examined for binding with a large number of North American BVDV isolates and eight strains of the serologically related pestivirus, hog cholera virus (HCV). No single BVDV monoclonal antibody reacted with all BVDV isolates. The most cross-reactive monoclonal antibody was an anti-p80/p125 antibody which showed a positive reaction with 173 of 180 (96%) North American isolates. From a fewer number of isolates tested, one anti-gp53 monoclonal antibody also showed a high cross-reactivity (94%). All BVDV isolates showed a positive reaction with at least one of the seven monoclonal antibodies in the panel. Thus, the results indicated that a pool of these monoclonal antibodies may be used in place of polyclonal antisera for the detection of BVDV contamination of cell lines or for virus isolation. For HCV, all three anti-p80/p125 monoclonal antibodies reacted positively with all eight virus strains. In contrast, none of the anti-gp53 monoclonal antibodies were reactive to HCV strains. Thus, the anti-gp53 monoclonal antibodies may be useful for distinguishing between usually innocuous BVDV infections and the highly significant HCV infections in swine for foreign animal disease surveillance.

Animals↗
PubMed1993

Immunogens of bovine viral diarrhea virus.

Bovine viral diarrhea virus (BVDV) is a ubiquitous pathogen of cattle that induces economically important diseases affecting multiple organ systems. In the United States, over 150 biological products are licensed for control of BVDV. These products contain live or killed BVDV, and many products contain other viruses or bacteria. Potency tests for these vaccines are based on animal inoculation and serology. For live virus vaccines, titration of viral infectivity in cell culture is an accepted alternative to animal inoculation. The immunogens in a killed virus vaccine may be measured by enzyme linked immunoabsorbent assay. Immunogens of BVDV that stimulate a protective immune response have not been conclusively identified. Epitopes on a putative viral envelope glycoprotein, gp53, are involved in viral neutralization. Other viral glycoproteins, gp48 and gp25, are immunogenic but epitopes on these proteins do not stimulate production of antibodies that efficiently neutralize virus. Progress in developing meaningful in vitro assays for quantitation of BVDV immunogens awaits identification of viral proteins that stimulate a protective immunity.

Animals↗
PubMed1993

Presumptive diagnostic differentiation of hog cholera virus from bovine viral diarrhea and border disease viruses by using a cDNA nested-amplification approach.

Hog cholera virus (HCV), bovine viral diarrhea virus (BVDV), and border disease virus (BDV) are closely related pestiviruses. BVDV and BDV are found worldwide but seldom cause disease in swine. In contrast, HCV has been successfully eradicated from swine in several nations but poses a potentially devastating threat to them because of its great virulence. Rapid differential diagnosis of HCV from BVDV and BDV infections in swine is vital for detection of the possible reintroduction of HCV into national herds from which it has been eradicated. Nested polymerase chain reactions (PCRs) for each of two pestiviral genomic segments are described. Amplification of the relatively conserved 5' genomic terminus identified 59 of 61 HCV, BVDV, and BDV isolates generically as pestiviruses. Nested amplification of the second region was designed to differentiate HCV from BVDV and BDV by exploiting relatively conserved differences in the nucleotide sequences that encode the major envelope glycoprotein. This second PCR correctly identified 36 of 36 diverse HCV isolates while failing to recognize any of 25 BVDV and BDV isolates. Multiple restriction fragment length analyses confirmed the identities of both external and nested PCR products. The two sets of PCRs may help confirm the generic identity of most pestiviruses and may permit presumptive differential diagnosis of HCV from BVDV and BDV.

Animals↗
PubMed1993

Comparison of nucleic acid hybridization and nucleic acid amplification using conserved sequences from the 5' noncoding region for detection of bovine viral diarrhea virus.

Primers and probes derived from conserved sequences located in the 5' noncoding region of pestiviruses were evaluated for detection of bovine viral diarrhea virus. With these reagents, hybridization and polymerase chain reaction tests detected 62 of 90 and 90 of 90 bovine viral diarrhea virus isolates, respectively. A quick lysis method for preparing RNA for use in polymerase chain reaction amplification also was evaluated.

Animals↗