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Biomedical subjects

J F Evermann

Publications and source records attributed to J F Evermann.

At least 37 records · Page 2Linked to original sources
PubMed1994

In utero infections responsible for abortion, stillbirth, and birth of weak calves in beef cows.

A multitude of in utero infections may cause abortion, stillbirths, or the birth of weak calves (see Table 1). Because the diagnostic success for determining the cause of abortions may be low (25%-40%), it is important that more knowledge about the causes and differential diagnoses is gained, and proper samples are collected and submitted. Use of an abortion diagnosis kit enables multiple samples to be analyzed and increases the likelihood of making a diagnosis. The immune response is suppressed during pregnancy. In part, this can be controlled by proper nutrition and appropriately timed vaccination programs.

Abortion, Veterinary↗
PubMed1994

Evaluation of agar gel immunodiffusion serology using caprine and ovine lentiviral antigens for detection of antibody to caprine arthritis-encephalitis virus.

The sensitivity of the agar gel immunodiffusion (AGID) test for the detection of antibody to caprine arthritis-encephalitis virus (CAEV) was investigated with CAEV or ovine progressive pneumonia virus (OPPV) as the source of antigen. A total of 218 goat serum specimens were tested for anti-CAEV antibody by AGID and immunoprecipitation of [35S]methionine-labeled CAEV. In comparison with that of immunoprecipitation, the sensitivity of the CAEV AGID test was 0.91, and that of the OPPV AGID test was 0.56. The AGID test with either antigen was 100% specific. The lower sensitivity of the OPPV AGID test in detecting caprine antibody to CAEV indicates that OPPV antigen is of limited value for use in CAEV diagnosis and control programs.

Animals↗
PubMed1994

Evaluation of a kinetic enzyme-linked immunosorbent assay for detection of caprine arthritis-encephalitis virus-specific antibodies.

A kinetic indirect enzyme-linked immunosorbent assay (k-ELISA) was evaluated for detection of antibody to caprine arthritis-encephalitis virus (CAEV), using sodium dodecyl sulfate-treated CAEV-63 as antigen. Two hundred fifteen caprine sera submitted to the diagnostic laboratory were tested for CAEV antibody by the k-ELISA and by immunoprecipitation of [35S]-methionine-labeled CAEV. A k-ELISA positive cutoff point of 80 yielded a sensitivity of 94.4% and a specificity of 100%, as compared with immunoprecipitation. A k-ELISA cutoff point of 50 resulted in a sensitivity of 100%, with 95.6% specificity. When sera with k-ELISA scores between 50 and 80 were considered suspect, testing of 1,001 diagnostic sera resulted in < 1.5% suspect reactions. Using the 80 cutoff point, the CAEV k-ELISA had good sensitivity and specificity, with the added advantages of quick turn-around time, few suspect reactions, and adaptability to large numbers of samples

Animals↗
PubMed1994

Isolation of pseudorabies (Aujeszky's disease) virus from a Florida panther.

Pseudorabies virus was isolated in cell culture from the brain tissue of a 3.5-year-old male Florida panther (Felis concolor coryi). The virus was not isolated from other tissues collected at necropsy. Based upon a nested polymerase chain reaction (PCR), the virus was determined to have the classical wild-type virulent genotype, glycoprotein I+ (gI+) and thymidine kinase+ (TK+).

Animals↗
PubMed1993

Identifying bovine respiratory syncytial virus by reverse transcription-polymerase chain reaction and oligonucleotide hybridizations.

An assay to identify tissue culture cells infected with bovine respiratory syncytial virus (BRSV) that utilizes reverse transcription (RT), the polymerase chain reaction (PCR), and a synthetic oligonucleotide hybridization probe has been developed. The RT-PCR assay uses a BRSV-specific negative-sense oligonucleotide primer to synthesize cDNA from a BRSV fusion protein mRNA template and another BRSV-specific oligonucleotide primer (positive sense) upstream from the negative-sense primer for PCR amplification. In the presence of mRNA templates of BRSV isolates originating from locations throughout the United States, the BRSV RT-PCR assay resulted in amplified products (381 bp) that were specific to BRSV, as demonstrated in hybridizations with a positive-sense oligonucleotide probe complementary to internal sequences and in sequence comparisons with the F protein of BRSV 391-2. In analysis of the BRSV RT-PCR assay with prototype strains of human RSV subgroups A and B, amplification of a similar 381-bp RT-PCR product was not evident, and no RT-PCR product hybridized with the internal probe. We conclude that the specific ability to amplify DNA sequences of BRSV F protein mRNA by RT-PCR and then to demonstrate the presence of the amplified product with a BRSV-specific oligonucleotide probe will greatly add to the speed, sensitivity, and specificity of BRSV diagnostics.

Animals↗
PubMed1993

Characteristic differences in reverse transcription-polymerase chain reaction products of ovine, bovine, and human respiratory syncytial viruses.

In reverse transcription-polymerase chain reactions (RT-PCR) and DNA hybridizations using primers and an oligonucleotide probe to the fusion (F) protein mRNA of bovine respiratory syncytial virus (BRSV), all the BRSV isolates and a goat isolate could be distinguished from prototype isolates of human respiratory syncytial viruses (HRSV) and ovine (sheep and bighorn sheep) respiratory syncytial viruses (RSV). However, RT-PCR amplifications with primers to sequences of the HRSV F protein mRNA resulted in amplified products of approximately 243 bp if mRNA templates of subgroup A HRSV strains were present and slightly larger amplified products with subgroup B HRSV strains. No amplified products were observed in HRSV-primed RT-PCR with BRSV or goat or ovine RSV mRNA templates. Although the ovine RSV isolates were antigenically cross-reactive with the goat RSV, HRSV and BRSV isolates, they were no amplified with either HRSV- or BRSV-specific primers in RT-PCR. These results confirm previous immunological comparisons suggesting that some ovine RSV isolates should be considered as distinct respiratory syncytial viruses.

Animals↗
PubMed1993

Seroprevalence of infectious disease agents in free-ranging Florida panthers (Felis concolor coryi).

Serum samples obtained from 38 free-ranging Florida panthers (Felis concolor coryi) in southern Florida, March 1978 through February 1991, were tested for antibodies against eight bacterial, parasitic, and viral disease agents. Sera were positive for antibodies against feline panleukopenia virus (FPV) (78%), feline calicivirus (56%), feline immunodeficiency virus/puma lentivirus (37%), feline enteric coronavirus/feline infectious peritonitis virus (19%), and Toxoplasma gondii (9%). All samples were seronegative for Brucella spp., feline rhinotracheitis virus, and pseudorabies virus. In addition, all the animals tested were negative for feline leukemia virus p27 antigen as determined by enzyme-linked immunosorbent assay. Feline panleukopenia virus was considered to be a potentially significant disease agent; FPV antibodies occurred in the highest prevalences in older age classes (P = 0.027) and in panthers living in the dense mixed hardwood swamps in the western portion of their range compared to the open cypress and sawgrass prairies to the east (P = 0.096). Because < 50 animals remain in this relict population and the probable resultant depression of genetic diversity and lowered disease resistance, FPV or other disease agents could contribute to the extinction of this endangered subspecies.

Animals↗
PubMed1993

Use of survival analysis to compare cull rates between bovine leukemia virus seropositive and seronegative dairy cows.

Bovine leukemia virus (BLV) infection and culling of cows in a commercial dairy herd were evaluated to determine whether a relation existed between the 2 factors. Cattle from the study population, a Holstein dairy herd consisting of approximately 400 milking cows, were tested for antibodies to BLV, using the agar gel immunodiffusion test, semiannually for 2 years, annually for 2 years, and when cattle were culled. Complete records of BLV test results were available for 849 (79%) of the 1,078 cattle that had at least 1 test during the study period. Using the Cox hazard model, the cull hazard rates (culls/cow-months) were greater for BLV seropositive cows than for seronegative cows > 36 months old. Hence, among older dairy cows, BLV-infected cows were culled prematurely, compared with uninfected cows.

Animals↗
PubMed1993

Prevalence of coronavirus antibodies in rabbits.

Antibodies to coronavirus were detected by an indirect fluorescent antibody test in rabbit sera from six rabbitries. The prevalence ranged from 3 to 40% in different rabbitries and most seropositive rabbits were more than 4 months old. A rabbitry with high prevalence of antibodies and high incidence of diarrhea could serve as a source of virus and aid in studying the natural history of coronavirus infection in rabbits.

Animals↗
PubMed1993

Suppression of lymphocyte proliferation by parainfluenza virus type 3-infected bovine alveolar macrophages.

Lymphocytes stimulated with concanavalin A (Con A) or antigen in the presence of bovine parainfluenza virus type 3 (PIV-3) infected bovine alveolar macrophages (BAM) or monocytes, had depressed [3H]thymidine incorporation. This failure of lymphocytes to incorporate radiolabel required live virus, was time dependent and was most pronounced when BAM were infected for 48 hr prior to the addition of lymphocytes. The rate of infection of alveolar macrophages and the release of infectious virus into culture supernatants paralleled suppression of lymphocyte mitogenesis by PIV-3. However, the peak titre of exogenous, live or inactivated virus was not suppressive when added to lymphocyte macrophage cultures just prior to Con A stimulation. Neither the loss of viable alveolar macrophages nor a shift in antigen or mitogen dose response in virally infected cultures could account for the deficit in [3H]thymidine incorporation by lymphocytes. Despite the presence of lymphocyte-associated virus antigen detected by direct immunofluorescence, no increase in PIV-3 titre above baseline was seen from infected lymphocytes, irrespective of mitogen stimulation. Likewise, lymphocytes did not contribute to the extracellular virus pool in lymphocyte-macrophage cultures as the increases in viral titre above basal levels in supernatants were equal to levels released by macrophages alone. The expression of viral antigen on lymphocytes stimulated in the presence of PIV-3-infected BAM suggests a non-productive or abortive infection of lymphocytes mediated through contact with infected macrophages.

Animals↗
PubMed1992

Effects of bovine leukemia virus infection on production and reproduction in dairy cattle.

The purpose of this study was to determine the effects of bovine leukemia virus (BLV) infection on production, reproduction and longevity in dairy cattle. The study population was a commercial Holstein dairy herd of approximately 400 milking cows. Cattle were tested for antibodies to BLV at least annually for three years and when culled. Four groups of culled cows were compared: seronegative cows (n = 79), seropositive cows without lymphocytosis (n = 176), seropositive cows with lymphocytosis (> or = 9,000 lymphocytes/microliter) (n = 74), and seropositive cows with lymphosarcoma (n = 29). Seropositive groups of cows were bred more times and had longer calving intervals than seronegative cows. The seropositive groups had greater 305-day ME (mature equivalent) FCM (3.5% fat-corrected milk) per lactation and were older when culled than seronegative cows. However, the percent fat per lactation was greater in seronegative cows. In the last complete lactation, differences in 305-day ME FCM, days open and cull age between groups were reduced and none were significant (p > 0.05). In the cull lactation, only cows with lymphocytosis had reduced milk production relative to seronegative cows, although this difference was not significant. After adjustment for initial production and reproductive values, only seropositive nonlymphocytotic cows were culled at a significantly older age than seronegative cattle. Lymphocytotic cows were culled four months younger on average than nonlymphocytotic seropositive cows. Hence, BLV infected cows had greater milk production on average than uninfected cows. Adverse effects of BLV infection were primarily limited to lymphocytotic cows which were culled earlier and had reduced milk production in the cull lactation.

Age Factors↗
PubMed1991

Rectal palpation and transmission of bovine leukemia virus in dairy cattle.

To determine whether rectal palpation, using common obstetrical sleeves, serves as a mode of transmission of bovine leukemia virus in dairy cattle, field studies were conducted at 2 dairies. At a commercial dairy, significant difference was not observed in rate of seroconversion in heifers and cows in which the same sleeve or new sleeves were used for palpations. At a university dairy, where cattle were used to teach dairy husbandry and veterinary procedures, significantly (P less than 0.02) greater rate of seroconversion was observed in heifers and cows palpated with unwashed common sleeves than that observed in heifers and cows palpated with sleeves washed between use. Although rectal transmission of bovine leukemia virus under field conditions was documented, it was related to frequency of palpation and age of cattle.

Animals↗
PubMed1991

Perspectives on the epizootiology of feline enteric coronavirus and the pathogenesis of feline infectious peritonitis.

This review presents some current thoughts regarding the epizootiology of the feline coronaviruses; feline infectious peritonitis virus (FIPV) and feline coronavirus (FECV) with primary emphasis on the pathogenesis of these viruses in nature. Although the mechanism(s) whereby FIPV causes disease are still incompletely understood, there have been significant contributions to the literature over the past decade which provide a framework upon which plausible explanations can be postulated. Two concepts are presented which attempt to clarify the pathogenesis of FIPV and at the same time may serve as an impetus for further research. The first involves the hypothesis, originally promulgated by Pedersen in 1981, that FIPV is derived from FECV during virus replication in the gastrointestinal tract. The second involves a unique mechanism of the mucosal immune system referred to as oral tolerance, which under normal conditions promotes the production of secretory immunity and suppresses the production of systemic immunity. In the case of FIPV infection, we propose that oral tolerance is important in the control of the virus at the gastrointestinal tract level. Once oral tolerance is disrupted, FIPV is capable of systemic spread resulting in immune-mediated vasculitis and death. Thus, it may be that clinical forms of FIP are due to a combination of two events, the first being the generation of FIPV from FECV, and the second being the capacity of FIPV to circumvent oral tolerance.

Animals↗
PubMed1991

Subacute effects of respiratory syncytial virus infection on lung function in lambs.

We examined the effects of ovine respiratory syncytial virus (RSV) infection on lung mechanics, lung histology, and airway reactivity in lambs. Nine lambs were inoculated with ovine RSV and seven control lambs with normal saline or viral media. Serum neutralization titers were obtained prior to and 3 weeks post-inoculation (PI). Open lung biopsies were performed 1 and 3 weeks PI. Lung mechanics including dynamic compliance (Cdyn), resistance of the lung (RL), and functional residual capacity (FRC) were measured 2 and 6 weeks PI using a plethysmograph. Airway reactivity to aerosolized carbachol, citric acid, and histamine was determined 2 and 6 weeks PI. Most RSV and control lambs were asymptomatic after inoculation. Control lambs had significantly greater average daily weight gain by the third week after inoculation. Seven RSV lambs tested had a fourfold or greater rise in serum neutralization titers, while two control lambs had a fourfold increase. At 2 weeks PI, RSV lambs had significantly lower FRC and higher RL. At 6 weeks RL remained significantly elevated in the RSV lambs. Airway reactivity was not increased in the RSV group. This animal model is useful for studying the effects of RSV infection on lung growth and lung function over time.

Animals↗