Evaluation of efficacy of three commercial vaccines against experimental bovine pneumonic pasteurellosis.

The objective of this study was to evaluate the efficacy of three commercial vaccines against experimental pneumonic pasteurellosis in cattle. The three vaccines were: (a) One Shot (SmithKline Beecham, West Chester, PA.), (b) Presponse (Langford Laboratories, Guelph, Ontario) and (c) Once PMH (BioCor, Omaha, NE.). Protective immunity was evaluated in terms of lower clinical and pneumonic lesion scores after endobronchial challenge with virulent P. haemolytica. The results indicate that One Shot elicited antibodies against leukotoxin (Lkt), capsular poly-saccharide (CP) and surface antigens (SA), while Presponse and Once PMH elicited antibodies against CP and SA. There was significant correlation between lung and serum antibody levels against Lkt (P < 0.0001), CP (P < or = 0.0001) and IROMPs (P < or = 0.035). Animals that received the One Shot had significantly (P < or = 0.05) lower mean pneumonic lesion score (36.6 +/- 10.97) as compared to the control group (48.6 +/- 25.92). A significant negative correlation (-0.41; P < or = 0.008) existed between serum antibody levels against Lkt and pneumonic lesion score. High serum antibodies against SA did not correlate with reduction in pneumonic lesion score. In addition, high antibody levels against CP did not correlate consistently with reduced pneumonic lesion scores. The results from this study demonstrates that commercial vaccines evaluated in this trial did not confer optimal protection in vaccinated calves, against experimental pneumonic pasteurellosis. However, One Shot vaccinates showed a better protective immunity compared to the other two vaccine groups.

Comparative evaluation of antibodies induced by commercial Pasteurella haemolytica vaccines using solid phase immunoassays.

The objective of this study was to evaluate the ability of four commercial vaccines to elicit antibodies against the leukotoxin (Lkt), capsular polysaccharide (CP), iron regulated outer membrane proteins (IROMPs), and whole cell (WC) antigens of Pasteurella haemolytica A1. Modified double antibody sandwich enzyme linked immunosorbent assays (ELISAs) were developed to measure antibody levels against Lkt, CP and IROMPs. An indirect ELISA was developed to measure the levels of antibody against WC antigens. The ideal cut off points for ELISAs were determined on receiver operating characteristic curves, using sera from 30 calves injected subcutaneously with a live P. haemolytica 12296 strain as positive control and sera from 30 colostrum-deprived calves as negative control. The vaccines evaluated were: 'One Shot' (SmithKline Beecham, West Chester, PA) a bacterin-toxoid, 'Presponse' (Langford Laboratories, Guelph, Ontario) a Lkt-rich culture supermatant, 'Once PMH' (BioCor Inc., Omaha, NE) a modified live vaccine, and 'Septimune' (Fort Dodge laboratories, Fort Dodge, IA) an outer membrane extract. Thirty, 4-6 week old Holstein calves were randomized into 5 groups to receive one of the four vaccines or a placebo (sterile phosphate buffered saline). The calves were vaccinated intramuscularly on day 0 and on day 14, and bled on days, 0, 14, and 28 to measure antibody levels against Lkt, CP, IROMPs, and WC antigens of P. haemolytica Al. 'One Shot', and 'Once PMH' vaccinates showed a significant (P < 0.05) increase in antibody levels against Lkt at 28 days. 'Once PMH' vaccinates also showed significant (P < 0.05) increase in antibody levels against IROMPs at 28 days compared to the other four groups but this increase was not significant over time within the 'Once PMH' group. 'Presponse', 'Once PMH' and 'One Shot' vaccinates showed a significant (P < 0.05) increase in antibody levels against CP over time. These groups also had significantly higher antibody levels against CP, compared to controls and 'Septimune' vaccinates at 14 and 28 days (P < 0.05).

Evaluation of three experimental subunit vaccines against pneumonic pasteurellosis in cattle.

The objective of this study was to evaluate the efficacy of three Pasteurella haemolytica A1 derived experimental subunit vaccines against pneumonic pasteurellosis in cattle. The three vaccines were: (a) culture supernatant (CS) containing leukotoxin (Lkt), lipopolysaccharide (LPS) and capsular polysaccharide (CP); (b) sodium salicylate extract (SSE) containing iron regulated outer membrane proteins (IROMPs), LPS and CP; (c) and a combination of the above two. Vaccine efficacy was defined in terms of reduction in clinical and pneumonic lesion scores after intrapulmonic challenge with live P. haemolytica. The results indicate that the CS vaccine elicited antibodies against both Lkt and CP, while the SSE vaccine elicited antibodies against IROMPs and CP. Animals inoculated with the combination vaccine showed increased levels of antibodies against IROMPs, Lkt and CP. There was significant correlation between lung and serum antibodies against Lkt, CP and IROMPs. Animals that received the combination vaccine had significantly lower mean pneumonic lung score as compared to SSE and control groups. The animals which received CS vaccine had mean pneumonic lung score significantly lower than that of control group. A strong negative correlation existed between serum antibody levels against Lkt, IROMPs, CP and pneumonic lung scores. The results from this study demonstrate the usefulness of CS vaccine alone or in combination with SSE vaccine in bringing about optimal protection in vaccinated calves, against experimental pneumonic pasteurellosis.

Immunohistochemical and pathological study of Mycoplasma bovis-associated lung abscesses in calves.

Out of 45 cases of fatal chronic pneumonia in calves examined for Mycoplasma bovis infection from February to July 1994, 11 cases with pulmonary abscesses that were culture positive for M. bovis were encountered. The cases were studied in detail using a recently developed monoclonal antibody-based immunoperoxidase technique. Mycoplasma bovis organisms were detected in specific locations at all stages of abscessation observed. In bronchioles or terminal airways within which abscesses developed, M. bovis was located at the epithelial surface and in close association with infiltrating neutrophils and macrophages. Abscessed airways that had lost the epithelium were encapsulated and were seen as coagulative necrotic foci that stained intensely for M. bovis, especially at the periphery. Some foci stained weakly and such might have been resolving lesions. Mycoplasma bovis was also demonstrated at sites of mild mononuclear cell infiltration in the livers and kidneys of 2 calves. The mycoplasma was detected within bile ducts in the liver and in the tubular epithelium of the kidney. Abscesses not staining for M. bovis, presumably caused by other pathogens, were seen concurrently with M. bovis-associated abscesses in some lungs. Thirteen other M. bovis-positive cases showed no abscesses, possibly indicating heterogeneity among M. bovis strains. Three other cases with abscesses were negative for M. bovis by culture and immunoperoxidase staining. The monoclonal antibody-based immunohistochemical technique is efficient for specific detection of M. bovis in cases of enzootic pneumonia of calves with or without abscessation. Mycoplasma bovis is implicated in the pathogenesis of lung abscesses in some calves.

Persistence of bovid herpesvirus-4 in experimentally inoculated pregnant rabbits.

To study the persistence and reactivation of bovid herpesvirus-4 (BHV-4), pregnant rabbits were inoculated with BHV-4 via the intrauterine route. Disease production and virus shedding were monitored for up to 67 days post infection (DPI). Virus isolation was attempted from nasal, vaginal and buffy coat samples of all rabbits. Virus shedding was observed between 5 and 12 DPI but not thereafter. Some of the animals were given intramuscular injections of dexamethasone (DEX) for 4 consecutive days starting at 7 weeks post infection. One group of rabbits was euthanized at 5 days post-DEX treatment (58 DPI) and the other was euthanized 2 weeks post-DEX treatment (67 DPI). Virus shedding was not detected in either group but BHV-4 was recovered on multiple occasions from spleen, kidney, uterus, and ovary explants of both DEX-treated and non-treated rabbits indicating that BHV-4 can persist in these organs but cannot be reactivated by DEX. To further study the in vitro reactivation of persistent BHV-4, a methylating agent, hexamethylenebisacetamide (HMBA), was used in organ cultures of neural and extraneural tissues. Limited data on enhanced recovery of BHV-4 from spleen indicated that it may be the site of latency in BHV-4 infection.

Variation in the pathogenic potential and molecular characteristics of bovid herpesvirus-4 isolates.

Seven bovid herpesvirus-4 (BHV-4) isolates recovered from various clinical conditions of cattle were studied for their pathogenic potential in pregnant rabbits. These viruses were originally recovered from respiratory and reproductive tract infections of cattle. A virus dose of 4 x 10(6.8)TCID50 per fetus was inoculated via the intrauterine route in 10- and 17-day pregnant rabbits. Clinical, virologic, and pathologic data were collected to compare the effect of each isolate on does and fetuses/kits. Three isolates (LVR-140, QVR-3140 and 86-068) caused abortion, fetal reabsorption and/or mummification in inoculated rabbits. Virus was recovered from tissues of inoculated rabbits (especially the spleen, ovaries and uterus) by organ explanation and/or co-cultivation. Intravenous inoculation of isolate 86-068 did not produce any clinical signs in either 10- or 17-day pregnant rabbits. All seven isolates of BHV-4 showed a predilection for the reproductive tract of pregnant rabbits but varied in the severity of disease signs produced. Variation was also observed in the genome of various isolates on the basis of restriction endonuclease (RE) analysis. Relationship of RE patterns to the variation in the pathogenic potential of seven BHV-4 isolates is discussed.

Evaluation of pregnant rabbits as a laboratory model for bovid herpesvirus-4 infection.

A field strain (87-8363) of bovid herpesvirus-4 (BHV-4) isolated from an aborted bovine fetus was used to inoculate pregnant rabbits. Eleven rabbits in midgestation were alloted to 4 groups consisting of 3 infected groups and 1 control group. Rabbits were inoculated with BHV-4 or mock-infected cell culture preparations via IV, intravaginal, and intrauterine routes. Mild vulvovaginitis and endometritis were observed after intravaginal and IV inoculation of BHV-4, whereas intrauterine inoculation of BHV-4 resulted in abortion of hemorrhagic fetuses and nonsuppurative endometritis. Virus was successfully isolated from organ explants of fetal tissues. Rabbits seroconverted 1 week after infection as detected by results of an indirect immunofluorescence assay.

Prevalence of bovid herpesvirus-4 and its antibody in cattle in Minnesota.

Serologic analyses and virus isolation studies were carried out to determine the role of bovid herpesvirus-4 (BHV-4) in infections in cattle, principally those of the reproductive tract. Serologic analyses were performed, using an indirect fluorescent antibody test on thoracic fluid specimens from aborted fetuses and on sera from 3 sources of adult cattle. Virus isolation was attempted from field cases of abortion, early embryo death, and postpartum vulvovaginitis/metritis, using uterine discharge and buffy coat preparations obtained from cows and tissues obtained from aborted fetuses. Of 420 fetal thoracic fluid specimens examined, 5 were positive for BHV-4 antibodies. Seventeen percent of adult cattle from 2 sources ie, clinically normal herds and abattoir cattle, were seropositive for BHV-4 antibodies. Cattle from a third source, 4 herds with high incidence of reproductive tract disorders, had a seroprevalence rate between 36 and 88%. Two isolates of BHV-4 were also obtained from this group. The overall incidence of BHV-4 antibodies in clinically normal cattle was higher than previously recognized, with relatively higher prevalence in herds having reproductive problems (chi 2 = 156.5, P less than 0.005). At least 10% of the BHV-4 antibody-positive sera did not have neutralizing antibody against bovine viral diarrhea virus and/or bovid herpesvirus-1, both important causes of bovine reproductive tract disorders.

Goitrogenic effects in offspring of swine fed sulfadimethoxine and ormetoprim in late gestation.

Effects of feeding sulfadimethoxine and ormetoprim to sows and gilts in late gestation were evaluated. One sow and 2 gilts were randomly selected and were fed 1 of 3 rations: (1) a gestation ration from farm A, where congenital goiter in newborn pigs was a problem, (2) gestation ration from farm A containing 275 g of sulfadimethoxine and 55 g of ormetoprim/100 kg of ration, or (3) standard swine gestation ration containing 275 g of sulfadimethoxine and 55 g of ormetoprim/100 kg of ration. Sows and gilts were fed the appropriate ration for 22 to 58 days before farrowing. The numbers of stillborn or weak pigs did not increase in any group. However, congenital goiter was detected in all pigs from swine fed medicated rations 2 and 3. Congenital goiter was not present in pigs from swine given gestation ration 1.

Diagnostic investigation of bovine viral diarrhea infection in a Minnesota dairy herd.

Bovine viral diarrhea (BVD) virus infection was diagnosed in neonatal calves with enteritis. Successful diagnostic procedures included direct immunofluorescence of frozen tissue sections, histopathology, and virus isolation. Virus isolation from buffy coats and serum was successful in detecting infected animals, whereas direct immunofluorescence of buffy coat samples was found to be less reliable. Virus was not isolated from any fecal samples. Booster vaccinations and the culling of animals shedding virus resulted in improved calf viability in this herd. It is suggested that procedures for the diagnosis of BVD virus infection should always be included in the diagnosis of neonatal calf enteritis.

Amino acid sequence variations in protein AA of cats with high and low incidences of AA amyloidosis.

1. Amyloid isolated from the liver of a domestic short-haired (DSH) cat was dissolved and purified by gel filtration for amino acid sequence analysis. 2. Sequences of two major peptides corresponding to positions 18-23 and 25-75 of human amyloid protein AA were obtained when cyanogen bromide-cleaved protein was applied to an amino acid sequenator. 3. Comparison of these regions of amyloid protein from the Abyssinian cat (high incidence of AA amyloidosis) and DSH cat (low incidence of AA amyloidosis) revealed three amino acid differences, two of which occurred within regions that are completely conserved in the Abyssinian cat and all other species. 4. Secondary prediction plots showed less potential for amyloidogenicity (i.e., less beta-sheet conformation) in protein AA of the DSH cat as compared to the Abyssinian cat and other animal species. 5. These differences in protein AA of the DSH cat may, therefore, be linked to the comparatively uncommon occurrence of AA amyloidosis in the DSH cat as compared to the Abyssinian cat and other animals species.

Effect of sulfadimethoxine-ormetoprim in the treatment of calves with induced Pasteurella pneumonia.

The efficacy of sulfadimethoxine (SDM)-ormetoprim (OMP) was evaluated in calves with induced Pasteurella pneumonia. A dose-titration study comparing 3 doses of SDM-OMP was performed to determine the optimal dose. Treatments included: group 1--nontreated controls; group 2--33 mg of SDM-OMP/kg of body weight, orally on day 1 and 17 mg/kg on days 2 to 5; group 3--66 mg of SDM-OMP/kg, orally on day 1 and 33 mg/kg on days 2 to 5; group 4--99 mg of SDM-OMP/kg, orally on day 1 and 50 mg/kg on days 2 to 5; and group 5--11 mg of oxytetracycline/kg, IV daily for 4 days. Group-2 calves responded to treatment as well as did group-5 calves. Group-4 calves responded the same as did group-3 calves. However, group-2 calves did not respond as well as did groups 3, 4, and 5 calves.

Study on the etiologic role of bovine respiratory syncytial virus in pneumonia of dairy calves.

Bovine respiratory syncytial virus (BRSV) was the viral agent most commonly identified in 14 epizootics of pneumonia in dairy calves. A microtiter serum-virus neutralization test proved to be the best means of identifying involvement of BRSV; seroconversion (fourfold or greater rise in titer) was demonstrated in 10 of the 14 epizootics. Only limited involvement of bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, parainfluenza 3 virus, and bovine adenovirus type 3 was recognized. Pasteurella multocida was isolated in 12 of 14 epizootics, and Pasteurella haemolytica in 4 of 14 epizootics. Mycoplasmal and ureaplasmal agents were isolated in all 14 epizootics.

Seroepizootiologic study of bovine respiratory syncytial virus in a beef herd.

A seroepizootiologic study of bovine respiratory syncytial virus in a beef herd was conducted from February 1983 through March 1984. During the study period, 3 separate respiratory tract disease epizootics were recognized in calves after they had been split into 3 groups. Bovine respiratory syncytial virus infection was diagnosed in each epizootic on the basis of serologic evidence, postmortem findings, and immunofluorescent examination of lung tissue. Additionally, there was serologic evidence for involvement of bovine adenovirus type 3 in the epizootics in 2 of the groups of calves, but not in the 3rd. In 2 groups of calves, respiratory tract disease occurred in 2 stages, with the 1st stage being mild followed by apparent recovery. The 2nd stage, which was associated with a change to colder weather, was clinically more severe, with death loss occurring.

Farm studies of porcine parvovirus infection.

Epizootics of reproductive failure associated with porcine parvovirus infection were investigated on 38 farms. Mummification was common to all epizootics. The mean number of mummified fetuses per affected litter was 3.1. Mean number of pigs born alive for gilts and sows farrowing litters with mummified fetuses was 5.0, but for sows without mummified litters on the same farms it was 9.0. Mummified fetuses were observed in aborted litters on 8 (21.1%) farms. Gilts and sows that appeared pregnant but "lost" their swollen abdomens and failed to farrow were observed on 12 (39.5%) farms. Delayed return to estrus was evident on only 3 (7.9%) farms with a continuous farrowing program. On 21 farms with a batch farrowing program, only 2 (10%) epizootics involved more than 1 batch. Up to 100% of the pregnant swine in the group farrowing together produced mummified pigs, but less than 20% of the breeding herd was affected in 26 (68.4%) cases. The prevalence of disease was not related to herd size, housing, or farrowing management.

Spontaneously occurring lymphoproliferative disease in ducks.

A naturally occurring lymphoproliferative disease was observed in a domestic flock of Muscovy ducks. Gross lesions were observed only in one of three ducks necropsied (in the small intestine). Microscopic lesions consisted of mononuclear cell infiltrates composed primarily of reticuloendothelial cells, mature lymphocytes, and plasma cells in livers, spleens, small intestines, peripheral nerves, and brains. Antibodies to reticuloendotheliosis virus were detected in sera of four ducks, whereas all six ducks examined lacked antibodies ot Marek's disease virus.

Porcine abortion caused by Actinobacillus equuli.

Actinobacillus equuli was isolated from an aborted porcine fetus. Fetal lesions of peracute embolic septicemia were similar to those seen in septicemic actinobacillosis of older swine and other species. This case represented an individual rather than a herd abortion problem.