A serologic survey was conducted to determine the prevalence and seroconversion rates for ovine adenovirus (OAV) serotypes 1-4 and bovine adenovirus (BAV) serotypes 2, 3, and 7 in sheep in Iowa and in surrounding states. For 2 consecutive years, paired serum samples were obtained from 1- to 2-month-old lambs as they entered a ram test station and, again, 2 months later. Sera were tested for adenovirus antibodies by use of a microtitration serum virus-neutralization test. At the time of entry, high prevalence of antibody (titer greater than or equal to 2) was detected to all tested adenoviruses except BAV-3. All adenoviruses were active in the ram test station both years, as indicated by greater than or equal to fourfold increase in adenovirus antibody titer (seroconversion) in some of the lambs. The prevalence and seroconversion rate for OAV-1 was 94.0 and 7.2%, respectively; for OAV-2, 98.6 and 15.1%; for OAV-3, 86.5 and 11.0%; for OAV-4, 98.4 and 13.2%; for BAV-2, 97.6 and 22.4%; for BAV-3, 11.4 and 3.8%; and for BAV-7, 81.6 and 4.5%. The results indicate that adenovirus infections were widespread in the sheep population and that the prevalence of active infection based on seroconversion rates was approximately 45%.

Hemagglutinins HA) of H1N1 swine influenza viruses isolated in the United States have remained antigenically and genetically conserved for many years. In contrast to such conservation, the RA of A/Swine/Nebraska/1/92 (Sw/Neb) could readily be distinguished from those of contemporary porcine viruses. Twenty-eight amino acid mutations differentiated the HA of Sw/Neb and A/Swine/Indiana/1726/88, the most recent H1N1 swine influenza virus for which HA sequence data were available. Among these differences were mutations at potential asparagine-linked glycosylation sites and charge changes at many residues. The Sw/Neb virus also could be differentiated from other swine influenza viruses in hemagglutination-inhibition assays with monoclonal antibodies to recent H1 swine HA. Nonetheless, overall sequence analysis of the HA and the nucleoprotein genes of Sw/Neb indicated that this virus was more closely related genetically to classic H1N1 swine influenza viruses than to H1N1 avian or human viruses. Infection of swine with Sw/Neb under experimental conditions induced clinical signs and lesions typical of swine influenza. However, affected swine in the field had high, persistent fevers, but relatively mild signs of respiratory tract disease. This study indicated that an antigenically and genetically novel variant of swine influenza virus was detected in the United States.

Twenty-four 10-month-old Polled Hereford heifers were inoculated sc with live cells of one of the following strains of Brucella abortus: S19 delta 31K (n = 4), S19 delta SOD (n = 4), RB51 (n = 4), and strain 19 (n = 6); controls (n = 6) were given saline solution. Heifers given the deletion mutants S19 delta 31K and S19 delta SOD, and those given strain 19 developed antibody responses to B abortus and cutaneous reactions to brucellin. Heifers given strain RB51 did not develop antibodies that reacted in the standard tube agglutination test, but sera reacted in tests, using an antibody dot-blot assay containing RB51 antigen. The S19 delta 31K and S19 delta SOD strains of B abortus isolated from lymph node tissue after vaccination did not differ genetically from the master stock strain. All heifers were bred naturally at 16 to 17 months of age, and were challenge-exposed intraconjunctivally with virulent B abortus strain 2308 during the fifth month of pregnancy. All vaccinated heifers were protected (ie, none aborted and none had B abortus isolated from their tissues after parturition). Calves born from vaccinated dams were free of B abortus. Antibody responses in heifers after challenge exposure were an indicator of immunity. All 5 control heifers (nonvaccinated) developed serum antibodies after challenge exposure; 3 aborted, and 1 delivered a small, weak calf at 8.5 months of gestation. Thus, live mutant strains of B abortus can induce protective immunity when given at 10 months of age, and strain RB51 is a strong candidate for further testing.

Cows and calves from a 1,600-cow drylot dairy were screened for IgG antibodies to Salmonella dublin lipopolysaccharide (LPS), using an indirect ELISA. The ELISA was performed on milk samples from lactating cows and on sera from nonlactating cows and calves. Fecal samples were collected from calves and nonlactating cows for culture of Salmonella spp. All seropositive cattle were retested by culture and ELISA 5 times at monthly intervals or until antibody concentration decreased. None of the cattle remained culture-positive and seronegative. Prior to and during the sample collection period, approximately 30% of calves < 8 weeks old died of S dublin infection. Vaccination of cows with a killed S dublin/S typhimurium vaccine at cessation of lactation was a routine management practice. The ELISA-determined Igg response to vaccination had decreased by 50 days after vaccination. Eight cows and 5 calves that maintained a high serologic response to S dublin were purchased and moved to a research facility for 6 months of intensive monitoring. Lactating cows were milked twice daily, and culture of milk and feces for Salmonella spp was performed 5 times/wk. Serum IgG antibodies to S dublin LPS were measured weekly, using ELISA. At the end of 6 months, all 13 cattle were necropsied and tissues were obtained for culture of Salmonella spp. All 8 cows and 5 calves maintained persistently high ELISA titer for the 6 months of testing, and shed S dublin in the milk and/or feces during the same period. On this basis, they were termed S dublin carriers. Salmonella dublin was isolated from mammary tissue of 2 calves at necropsy, indicating that bacteremia may be a mode of mammary infection by S dublin. Results of the study indicated serologic testing can be used successfully on a large dairy to identify S dublin carrier cattle. Using initial milk screening, 42 of 1,268 lactating cows were identified as suspect, requiring repeated serologic testing. One nonlactating cow, 7 of the 42 suspect lactating cows, and 5 of the 222 calves maintained an Igg response, and were found to be S dublin carriers. Carrier cows shed S dublin in 3.35% of fecal samples and 2.51% of milk samples, and carrier calves shed S dublin in 17.26% of fecal samples.

Four-week-old chickens were inoculated orally with 1,000 or 100,000 oocysts of the ME-49 or GT-1 strain of Toxoplasma gondii, and their antibody responses were measured, using the direct modified agglutination test, latex agglutination test, indirect hemagglutination test, ELISA, and the Sabin-Feldman dye test. Antibodies against T gondii were detected by use of the modified agglutination test and ELISA within 2 weeks of oocyst inoculation, and antibodies persisted until termination of the study by postinoculation day 68. The latex agglutination test was insensitive in detecting T gondii antibodies, and antibodies were not detected by use of the dye and indirect hemagglutination tests. Of tissues bioassayed in mice for tissue cysts by pepsin digestion of individual organs of chickens on postinoculation day 68, tissue cysts were found in the brain of all 5, heart of 3, and leg muscles of 2, but not in the liver and breast muscles. None of the birds developed clinical toxoplasmosis.

Serum triiodothyronine autoantibody (T3 AA), triiodothyronine (T3), and thyroxine (T4) concentrations were determined in 45 canine sera containing substantial amounts of thyroglobulin autoantibodies (Tg AA); sera also were assayed to investigate the ability of free T3 to inhibit Tg AA binding to canine Tg. Serum T3 AA concentrations defined 2 groups of sera; 28 sera had low T3 AA concentration (less than or equal to 20 ng/ml) and 17 sera had high T3 AA concentration (greater than or equal to 250 ng/ml). Direct linear correlation between T3 AA concentration and apparent serum T3 concentration was observed (r = 0.75). Serum with low T3 AA concentration had apparent T3 concentration that was significantly (P < 0.01) lower than that in serum with high T3 AA concentration. Mean serum T4 concentration was not significantly different between serum with low or high T3 AA concentration. Mean Tg AA activity was significantly (P < 0.05) lower in serum with low T3 AA concentration than in serum with high T3 AA concentration. Addition of free T3 to serum significantly (P < 0.05) decreased detectable activity of Tg AA in both groups of sera. However, significant difference in magnitude of the reduction was not observed between sera with low or high T3 AA concentration. Results indicate that a fraction of Tg AA recognizes T3-containing epitopes in Tg. Increased prevalence of T3 AA for serum with high Tg AA activity indicates that T3 AA may be another valid indicator of lymphocytic thyroiditis. These antibodies may be generated against the hormonogenic epitopes of Tg.

The role of interleukin-1 (IL-1), interleukin-6 (IL-6), and tumor necrosis factor a during endotoxin-induced mastitis in cows was characterized. Six cows had 10 microgram of Escherichia coli lipopolysaccharide infused into 1 mammary gland. Three other cows served as nontreated controls. Within 1.5 to 2.5 hours after infusion, endotoxin caused obvious edema of the mammary gland and increased serum albumin concentration in milk of infused glands 6 times. Milk somatic cell count began to increase 3 to 5 hours after infusion in all treated glands. At 7 hours after infusion, somatic cell counts were increased > 10 times, compared with counts in milk from control cows. Pyrexia of > 1 C developed in only 1 cow, but all treated cows had serum cortisol concentrations > 50 ng/ml in response to endotoxin treatment. High concentrations of IL-1 (10 to 600 U/ml) and IL-6 (2 to 22 U/ml) were detected in milk of infused glands beginning 2.5 to 4 hours after infusion. Endotoxin did not induce detectable amounts of tumor necrosis factor activity in milk or serum. Swelling and mammary gland permeability changes preceded any detectable increase in IL-1 and IL-6 activity, indicating that these clinical signs of inflammation were not mediated by these cytokines. Systemic responses and the leukocytic influx into endotoxin-infused glands developed after or concurrently with initial increases in IL-1 and IL-6 activities in milk. These results suggested that IL-1 and IL-6 may have a role in mammary gland defenses and in the pathophysiologic changes during endotoxin-induced mastitis.

A double-antibody sandwich ELISA (DAS-ELISA) was developed for detection of avian influenza virus (AIV) antigen. A monoclonal antibody to the viral nucleoprotein (NP) was used to coat the ELISA plates. A direct DAS-ELISA and an indirect DAS-ELISA were evaluated. In the direct DAS-ELISA, monoclonal antibody to the AIV NP conjugated with horseradish peroxidase was used. The direct DAS-ELISA was evaluated for its sensitivity to detect purified NP; this procedure detected as little as 0.1 ng. In the indirect DAS-ELISA, rabbit NP antibody and horseradish peroxidase-conjugated goat anti-rabbit immunoglobin were used as primary and secondary antibodies, respectively. The indirect DAS-ELISA was evaluated for its ability to detect the AIV antigen in tracheal and cloacal specimens from turkeys inoculated with AIV. Results of indirect DAS-ELISA were compared with those of conventional virus isolation. Percentage agreement between indirect DAS-ELISA and virus isolation in AIV-positive samples was found to be 76.1% and, in AIV-negative samples, it was found to be 82.1%. These results indicate that the DAS-ELISA might be a viable alternative to virus isolation because of its rapidity, compared with virus isolation.

During the spring of the first year of a vaccine study, 57 of 238 calves (24%), in which modified-live Pasteurella haemolytica vaccine (MLV) was injected twice, developed 1 or more abscesses. Abscesses were not observed after multiple visual examinations of 437 calves given killed P. haemolytica bacterin or placebo injections of similar adjuvants used in the vaccine and bacterin. Calves that developed abscesses after the second injection of MLV weighed significantly (P < 0.05) less (on the basis of body weight adjusted for weaning weight) at the second injection than did those that did not develop abscesses. Compared with calves given MLV that did not develop observable abscesses, calves developing abscesses after the second injection of MLV weighed 11.0 and 14.2 kg less, respectively, at 56 days and 112 days after injection, and they had 11.0 kg less gain at 56 days after injection. Abscess prevalence tended to be highest on certain days or at certain locations used for cattle processing, and the prevalence of abscesses increased in cattle processed later on a given day. Abscesses were not observed in 2 other groups of similarly treated calves vaccinated in the autumn or in the subsequent spring.

The ability of viral glycoproteins (VP) VP4/VP7 reassortant swine rotaviruses (RV) to induce cross-neutralizing antibody against parental serotypes was investigated in guinea pigs. Using selective culture conditions, we produced 10 reassortant viruses that contained gene segment 4 of the OSU RV strain and gene segment 9 of the Gottfried RV strain. These reassortant RV grew to high titer in cell culture and were neutralized by monospecific antisera against both parental RV strains. The reassortant RV were chemically inactivated with binary ethylenimine, adjuvanted with aluminum hydroxide, and used to produce antisera in guinea pigs. The hyperimmune antisera had high neutralization titer against both parent RV strains. These results indicate that several of the reassortant RV may be capable of inducing neutralizing antibodies to VP4 and VP7 and may have future use as bivalent vaccine strains.