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Biomedical subjects

B I Osburn

Publications and source records attributed to B I Osburn.

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

Meat from dairy cows: possible microbiological hazards and risks.

The authors provide an overview of the circumstances associated with culling of dairy cattle in the United States of America (USA) and focus on the possible significant microbiological hazards associated with meat from cull dairy cows. Cull dairy cows are an important source of food in the USA, accounting for at least approximately 17% of ground beef. The potential microbiological hazards for foodborne illness from cull dairy cows discussed here include Salmonella (with special attention to S. Typhimurium DT104), Escherichia coli O157:H7, Campylobacter jejuni, Listeria monocytogenes, Clostridium perfringens and Staphylococcus aureus. Possible sources and means of contamination are pointed out, as are the potential foodborne risks from Bacillus cereus and Aeromonas spp. In conclusion, widespread microbiological studies are needed to determine the prevalence and risk of foodborne pathogens in cull dairy cattle.

Animals↗
PubMed1996

Comparative susceptibility of a canine cell line and bluetongue virus susceptible cell lines to a bluetongue virus isolate pathogenic for dogs.

Recently, bluetongue virus (BLU) serotype 11 was detected in diseased dogs that had been inoculated with live attenuated vaccine contaminated with this serotype of bluetongue virus (Akita et al., 1994). For various laboratory tests, BLU can be propagated in different cell cultures. No information was found in the literature about the possibility of propagating this virus in canine cells. To determine whether the BLU isolate from the contaminated canine vaccine (BLU-vac) is unique in its ability to replicate in canine cells, this virus was studied in parallel with U.S. prototype strains of BLU (serotypes 2, 10, 11, 13, and 17), in hamster lung (HmLu-1) and canine kidney (MDCK) cell cultures. In HmLu-1 cell cultures, the BLU-vac produced cytopathic effect (CPE) of the same type as the U.S. prototype BLU strains by 4 to 6 d postinoculation. In MDCK cell cultures, all of the BLU strains tested were able to replicate but did not produce CPE. The BLU-inoculated MDCK cells became persistently infected, and these cultures continued to produce infectious BLU even after six serial passages over 2 1/2 mo. In none of these cultures was CPE observed. In mixed cultures containing both HmLu-1 and MDCK cells, CPE first affected the HmLu-1 islands; subsequently, CPE spread also to the areas with MDCK cells. The silent persistent infection of the MDCK cells with BLU indicates that more stringent screening of the cells used in the production of live vaccines for various contaminating viruses is necessary.

Animals↗
PubMed1996

A non-specific defence inducer in preventing clinical signs of infectious bovine rhinotracheitis in calves.

One calf was infected with bovine herpesvirus-1 (BHV-1) and mixed with five other calves, of which one had been vaccinated with a BHV-1 modified live vaccine one month earlier. The other four calves were vaccinated at the time the experimentally infected calf developed the first signs of the disease (fever, depression, nasal discharge), i.e. on post infection day (PID) 2. In addition to the vaccine, two of the four PID 2 vaccinated calves also received a non-specific defence (NSD) inducer (Baypamun, Bayer AG) at the same time as the vaccine. The calf that was vaccinated 1 month before the start of the experiment, as expected, did not show any signs of the disease. Of the remaining four, the two vaccine-only calves experienced a classical form of infectious bovine rhinotracheitis. However, the two calves that had also received the NSD inducer remained generally healthy during the entire observation period of 30 days. It was speculated that the use of a NSD inducer once an outbreak of a respiratory disease has started on a farm could be of significant help in an emergency in reducing the clinical manifestations in those animals that may subsequently be infected.

Adjuvants, Immunologic↗
PubMed1996

Bluetongue disease and the molecular epidemiology of viruses from the western United States.

Prototype and field isolates of United States bluetongue viruses were evaluated for genetic heterogeneity by sequence analyses. Prototype viruses BTV 2, 10, 11, 13 and 17 from the United States, BTV 10 vaccine virus, and field isolates of BTV 10 and 17 from California were analyzed. Gene segment 2 from BTV 10 and 17 isolated in 1980-81 and 1990 was sequenced along with gene segment 9 from BTV 10 isolates. The Wisconsin Package was used to analyze nucleotide sequences and to predict amino acid composition of the putative proteins. Phylogenetic analyses were done using DNADIST and FITCH programs of the PHYLIP Package, v. 3.4. Gene segment 2 segregated into two monophyletic groups of BTV 2 and 13 and BTV 10, 11 and 17. BTV prototype 10, isolated in 1953 and field isolates through 1980 were similar, whereas the 1990 isolates differed by 4.5%, indicating two BTV 10 monophyletic groups over 37 years. Gene segment 2 of BTV 17 prototype virus differed from the California isolates. Gene segment 9 of BTV 10 field isolates formed into two monophyletic groups. This gene segment reassorted with all serotypes. Gene segment 9 of the 1953 BTV 10 vaccine virus was essentially the same as gene segment 9 of the BTV 13 prototype virus, isolated in Idaho in 1967. This suggested that prototype BTV 13 is a reassortant virus with gene segment 9 derived from a vaccine virus parent.

Amino Acid Sequence↗
PubMed1996

Application of molecular biological techniques for detection of epizootic hemorrhagic disease virus (EHDV-318) recovered from a sentinel calf in central Sudan.

Epizootic hemorrhagic disease virus (EHDV), isolate 318 (EHDV-318), an untyped virus recovered from a sentinel calf herd at the Khartoum University farm in central Sudan, was characterized using molecular biological techniques. With dot blot hybridization technique, a cDNA probe derived from genome segment 6 of EHDV-2 (Alberta strain) hybridized with RNA from EHDV-318. Application of serogroup-specific EHDV polymerase chain reaction (PCR) to EHDV-318 RNA resulted in specific amplification of a 387 bp PCR product. Amplification product was visualized on ethidium bromide-stained agarose gel. Specificity of the PCR products was confirmed by chemiluminescent hybridization with a non-radiolabelled internal probe. No amplification product or hybridization signal was detected when the serotype-specific EHDV-1 or EHDV-2 PCR-based assays were applied to RNA from EHDV-318. The scientific data presented in this study indicated that cDNA probes and serogroup-specific PCR-based assay can be used to classify the virus as a member of EHDV serogroup, and as serotypically distinct from EHDV-1 and EHDV-2.

Animals↗
PubMed1996

Genetic characterization of rabies field isolates from Venezuela.

Twenty samples from cases of rabies in humans and domestic animals diagnosed in Venezuela between 1990 and 1994 and one sample from a vampire bat collected in 1976 were characterized by reactivity to monoclonal antibodies against the viral nucleoprotein and by patterns of nucleotide substitution in the nucleoprotein gene. Three antigenic variants were found: 1, 3, and 5. Antigenic variant 1 included all samples from dogs and humans infected by contact with rabid dogs. Unique substitutions permitted identification of two separate outbreaks of dog rabies in the Maracaibo Depression and Los Llanos region and in the Andean region of Venezuela. Samples from the vampire bat and two head of cattle were characterized as antigenic variant 3 and showed a nucleotide sequence homology of 96 to 98% to each other and to samples of vampire bat-associated rabies throughout Latin America. Ten of the remaining 12 samples were characterized as antigenic variant 5. Genetic studies indicated that 11 of these samples formed a highly homologous and distinctive group but were closely related to samples of vampire bat-associated rabies. The 12th sample of variant 5 (from a cat) showed only 78 to 80% genetic homology to samples of rabies associated with vampire bats. The application of antigenic and genetic typing to rabies surveillance in Latin America is essential to improve control programs. Recognition of the source of outbreaks of dog rabies and identification of wildlife species maintaining sylvatic cycles of rabies transmission permit better utilization of public health resources.

Animals↗
PubMed1996

Phylogenetic comparison of the S3 gene of United States prototype strains of bluetongue virus with that of field isolates from California.

To better define the molecular epidemiology of bluetongue virus (BTV) infection, the genetic characteristics and phylogenetic relationships of the S3 genes of the five U.S. prototype strains of BTV, the commercially available serotype 10 modified live virus vaccine, and 18 field isolates of BTV serotypes 10, 11, 13, and 17 obtained in California during 1980, 1981, 1989, and 1990 were determined. With the exception of the S3 gene of the U.S. prototype strain of BTV serotype 2 (BTV 2), these viruses had an overall sequence homology of between 95 and 100%. Phylogenetic analyses segregated the prototype U.S. BTV 2 strain to a unique branch (100% bootstrap value), whereas the rest of the viruses clustered in two main monophyletic groups that were not correlated with their serotype, year of isolation, or geographical origin. The lack of consistent association between S3 gene sequence and virus serotype likely is a consequence of reassortment of BTV gene segments during natural mixed infections of vertebrate and invertebrate hosts. The prototype strain of BTV 13, which is considered an introduction to the U.S. like BTV 2, presents an S3 gene which is highly homologous to those of some isolates of BTV 10 and especially to that of the vaccine strain. This finding strongly suggests that the U.S. prototype strain of BTV 13 is a natural reassortant. The different topologies of the phylogenetic trees of the L2 and S3 genes of the various viruses indicate that these two genome segments evolve independently. We conclude that the S3 gene segment of populations of BTV in California is formed by different consensus sequences which cocirculate and which cannot be grouped by serotype.

Bluetongue virus↗
PubMed1996

Epitheliocystis infection in cultured white sturgeon (Acipenser transmontanus): antigenic and ultrastructural similarities of the causative agent to the chlamydiae.

A mild to moderate branchial epitheliocystis infection was diagnosed in subyearling (11 months old, 250-300 g) white sturgeon (Acipenser transmontanus) from a private culture facility with a 4-8% mortality in the population. Infected branchial epithelial cells contained the coccoid to coccobacillary epitheliocystis organisms, which appeared as cytoplasmic inclusions composed of a fine, homogeneous, dense, basophilic, granular material. The infected cells were variably enlarged with spherical to oval profiles and were randomly distributed throughout the branchial epithelium. The cytoplasmic inclusions stained positive with Macchiavello stain but negative with Brown and Brenn, periodic acid-Schiff, and Gimenez stains. Expression of chlamydial antigen was demonstrated within the cytoplasmic inclusions using a standard peroxidase-antiperoxidase immunohistochemical technique. Three stages of coordinated intracellular development were recognized by electron microscopy. The reticulate bodies were oval to spherical and 0.4-0.8 x 0.5-1.4 microns but often exhibited a pleomorphic and convoluted appearance because of variable membrane invaginations and evaginations suggestive of uneven fission and budding. Separate host cells contained intermediate bodies that were spherical to oval and 0.2-0.4 x 0.3-0.6 microns although often observed in the process of apparent uneven division. The presence of a cap or plaque composed of hexagonally arrayed fibrillar surface projections was initially recognized in this stage. A homogeneous population of 0.3-0.4 microns oval elementary bodies were observed separately in individual host cells. This developmental stage had a single, dense, compact, eccentrically located cytoplasmic condensation that occurred opposite to the location of the cap of hexagonally arrayed fibrillar surface projections. Morphologic characteristics of the epitheliocystis organism in these white sturgeon were similar to those previously described in other teleosts and expands the species catalogue of epitheliocystis infection. Furthermore, the ultrastructural similarities to the chalmydiae and the immunohistochemical detection of chlamydial antigen provides further evidence that the epitheliocystis agent is related to members of the Chlamydiales. Although the infection was considered mild to moderate and could not be definitively attributed to the mortality in this population, the potential adverse impact of epitheliocystis infection on sturgeon culture should be considered especially in intensive fish culture operations.

Animals↗
PubMed1996

PCR detection of acute Ehrlichia canis infection in dogs.

A polymerase chain reaction (PCR)-based detection assay that specifically detected Ehrlichia canis in dogs with acute infections was developed. A region of the 16S ribosomal RNA gene of E. canis was targeted for PCR amplification and chemiluminescent hybridization (CH) with a complementary internal 287-base pair (bp) oligonucleotide probe. The CH improved the PCR assay sensitivity 1,000-fold as compared with visualization on ethidium bromide-stained agarose gels. The PCR assay with CH (PCR/CH) detected as little as 30 fg of E. canis genomic DNA, the equivalent of approximately 150 E. canis organisms. The 495-bp product defined by the specific primers was not detected when genomic DNA from E. platys, E. chaffeensis, E. risticii, and E. equi were used in the PCR/CH assay. The PCR/CH assay was tested with unfractionated blood samples collected from 9 dogs experimentally infected with E. canis. The PCR/CH assay had greater detection sensitivity than did cell culture isolation (CCI) from infected blood. PCR/CH detected E. canis 7 days prior to CCI in 4 of 6 experimentally infected dogs. The results obtained with the PCR/CH assay otherwise consistently matched the results obtained by CCI. This PCR/CH assay is a rapid, sensitive, and specific method for E. canis detection with sensitivity comparable to or exceeding that of CCI. A diagnosis of E. canis using this PCR/CH assay can be made in 2 days as compared with 1-4 weeks for CCI. The PCR/CH assay appears to be an acceptable alternative or complement to current diagnostic techniques.

Animals↗
PubMed1996

Emerging diseases with a worldwide impact and the consequences for veterinary curricula.

Emerging infections are being recognized at an alarming rate. In the case of emerging viral infections involving free-ranging wildlife, the intrusion of urban and agricultural enterprises into wildlife habitats appears to be playing a major role in the exchange of infectious agents of domestic to wildlife species and vice-versa. It is important that the veterinary profession prepares itself to respond to the threatening challenges. Creation of a course which addressed the principles of infectious diseases, diagnostic medicine, epidemiology, public health, population medicine and control are all imperative. This paper attempts to address some of the principle subjects matter areas which should be included in the course offering.

Animals↗
PubMed1995

Growth of a neuroinvasive strain of bluetongue virus in suckling mice.

Some strains of bluetongue virus cause congenital brain damage in bovine and ovine fetuses, as well as in neonatal mice. Two strains of bluetongue virus serotype 11 (UC-2 and UC-8) which differ in neuroinvasiveness were used to determine the biological basis for this difference. UC-2 and UC-8 were inoculated subcutaneously into newborn mice and virus was titrated from blood, plasma and brain tissues over 14 days. For the invasive UC-8 strain, 50-175 plaque forming units of virus per ml was found associated with the blood cells and no virus was detected in the plasma. The virus was detected in the brain at day one post inoculation, and again at day 7, increasing to day 11. The results indicate that UC-8 was able to reach the brain soon after inoculation and to replicate and/or remain in the blood circulation better than UC-2. Immunohistochemical examination of frozen brain sections revealed a sudden, multifocal appearance of UC-8 at day 9, with more viral antigen seen at days 11 and 13, which was barely detected by day 15. Viral antigen was not associated with blood vessels in the brain, indicating that the viral invasion was not from infected vascular endothelium. No virus was detected in the mice infected with strain UC-2.

Animals↗
PubMed1995

Development of polymerase chain reaction for specific identification of epizootic hemorrhagic disease virus serotype 1.

The diagnostic potential of the polymerase chain reaction (PCR) for specific identification of epizootic hemorrhagic disease virus serotype 1 (EHDV-1) in cell culture and clinical specimens was evaluated. Using oligonucleotide primers, selected from genome segment 2 of EHDV-1 (New Jersey strain), the PCR-based assay resulted in a 862 base pair (bp) PCR product. EHDV-1 RNA from United States prototype serotype 1 and a number of EHDV-1 field isolates, propagated in cell cultures, were detected by this PCR based assay. The specific 862 bp PCR products were visualized on ethidium bromide-stained agarose gel. Identity of the PCR product was confirmed by chemiluminescent hybridization with non radiolabelled internal probe. Using chemiluminescent hybridization, the sensitivity of the PCR assay was 1.0 fg of virus RNA (equivalent to 60 virus particles). Amplification product was not detected when the PCR-based assay was applied to RNA from EHDV serotype 2 (EHDV-2); the United States bluetongue virus (BLU) prototypes serotypes 2, 10, 11, 13, and 17; total nucleic acid extracts from uninfected BHK-21 cell; or blood cells from calves and deer that were EHDV-seronegative and virus isolation negative. Application of this EHDV-1 PCR-based assay to clinical samples resulted in detection of EHDV-1 RNA from blood samples, collected from a calf experimentally infected with EHDV-1. The described PCR-based assay provides a simple, rapid, sensitive, specific and inexpensive method for specific identification of EHDV-1 infection in susceptible ruminants.

Animals↗
PubMed1995

Associations among prostaglandin F2alpha, plasma zinc, copper and iron concentrations and fetal loss in cows and mares.

The objective of this study was to test the hypothesis that PGF2alpha is associated with abortion and changes in plasma Zn, Cu, and Fe concentrations in cows and mares in their first trimester of pregnancy. Eleven pregnant cows were infused with endotoxin (n = 5) or endotoxin plus an inhibitor of cycloxygenase, flunixin meglumine (n = 6). Blood was collected over a 5-d period. Additionally, 4 mares were treated every 24 h with cloprostenol sodium and blood was collected hourly until abortion. Plasma Zn, Cu, and Fe were determined. Three of five cows treated with endotoxin aborted, but none of the six cows treated with endotoxin and flunixin meglumine aborted. Aborting cows had lower plasma Zn (P = 0.048) over the 5-d study period compared with the nonaborting cows. The changes in Zn corresponded to release of PGF2alpha. All 4 mares aborted and plasma Zn concentrations were lower (P = 0.008) and Cu/Zn was higher (P = 0.02) 12 h after cloprostenol treatment. Plasma Zn may be a useful biomarker for risk of spontaneous abortion, and the decline in plasma Zn may be caused by PGF2alpha.

Journal Article↗
PubMed1995

The use of a non-specific defence mechanism inducer in calves exposed to bovine herpesvirus-1 infection: preliminary trials.

The efficacy of an immunomodulator, the Baypamun (Bayer AG), was tested in calves which were subsequently exposed to bovine herpesvirus-1 (BHV-1) infection. Two groups of calves, of 8 animals each, were used for two trials. In one trial, 4 calves were treated with the immunomodulator and the remaining 4 were left as untreated controls. Two hours after the first injection of Baypamun, all calves, i.e. the treated and the untreated ones, were challenged with BHV-1. Comparing them to the untreated controls, the calves which were given the immunomodulator developed milder signs of the disease and shed a significantly lower concentration of virus. In the second experiment, 4 calves were given Baypamun and 4 calves were not, as above, but they were not inoculated with BHV-1; however, they were housed together with the calves of the former group (experimentally infected with BHV-1). The 8 calves all became infected but those that had been treated with Baypamun did not show any clinical signs of the disease, whereas the untreated calves underwent a clinical response which was considered to be typical of BHV-1 respiratory infection, as usually seen under natural conditions. In this case the shedding of virus by the calves treated with the immunomodulator also underwent a significant reduction.

Adjuvants, Immunologic↗
PubMed1995

Prevalence of group A and group B rotaviruses in the feces of neonatal dairy calves from California.

136 fecal samples, collected from 47 dairy calves on a calf ranch and in a dairy herd in California, were tested for the presence of group A and group B rotaviruses by reverse transcription-polymerase chain reaction (RT-PCR). Samples were collected from each calf at days 1, 7 and 14. Within the 14 day period, 44 calves (94%) were positive for group A rotavirus and an unexpectedly high number of calves (38 calves, 81%) were positive for group B rotavirus. When these samples were examined by polyacrylamide gel electrophoresis (PAGE), rotavirus was found in 21 calves and all of them had group A electropherotype. Among 25 PAGE positive samples from 21 calves, 17 (68%) were of short electropherotype, 4 (28%) were of long electropherotype and 4 (28%) contained both short and long electropherotype rotaviruses. Group B and short and long electropherotype group A rotaviruses were found in both normal and diarrheic calves.

Animals↗
PubMed1995

African horse sickness and African carnivores.

African horse sickness (AHS) is a disease that affects equids, and is principally transmitted by Culicoides spp. that are biological vectors of AHS viruses (AHSV). The repeated spread of AHSV from sub-Saharan Africa to the Middle East, northern Africa and the Iberian peninsula indicate that a better understanding of AHS epizootiology is needed. African horse sickness has long been known to infect and cause mortality among domestic dogs that ingest virus contaminated meat, but it is uncertain what role carnivores play in transmission of the virus. We present evidence of widespread natural AHS infection among a diversity of African carnivore species. We hypothesize that such infection resulted from ingestion of meat and organs from AHS-infected prey species. The effect of AHS on the carnivores is unknown, as is their role in the maintenance cycle of the disease.

Africa↗
PubMed1995

Comparison of polymerase chain reaction and virus isolation for detection of epizootic hemorrhagic disease virus in clinical samples from naturally infected deer.

We compared our recently reported reverse transcriptase polymerase chain reaction (PCR)-based assay for detection of epizootic hemorrhagic disease virus (EHDV) in clinical samples with different virus isolation (VI) procedures. Thirty-six blood samples and 1 spleen sample from deer were assessed by the EHDV PCR assay and VI in baby hamster kidney (BHK)-21 cells and embryonated chicken eggs (ECE). The EHDV PCR assay detected EHDV RNA from 6 blood samples obtained from deer during 1988-1989 outbreaks of epizootic hemorrhagic disease and from the spleen and blood samples of a deer with clinical hemorrhagic disease in 1992. The 6 blood samples from the 1988-1989 outbreaks and the spleen sample from the 1992 case were VI positive on BHK-21 cell culture. The blood from the same deer with the PCR- and VI-positive spleen was VI negative in BHK-21 cells and ECE. All EHDV isolates were identified as EHDV serotype 2 by a plaque inhibition test. The results of this study indicate that the sensitivity of the previously described EHDV PCR assay is comparable to or greater than that of the VI method in BHK-21 cell culture or ECE. The EHDV PCR assays could provide a superior diagnostic alternative to the current cumbersome and time-consuming VI procedures.

Animals↗