Infectious hematopoietic necrosis virus (IHNV) was detected in the common Mayfly (Callibaetis sp) by western immunoblot assay and was propagated in fish cells (CHSE-214) in culture. When propagated in cell culture, cytopathic effect characteristic of IHNV infection was observed. Antibody specific for IHNV was used to detect all of the major proteins of IHNV in the western immunoblot assay. When the crude lysate was subjected to electron microscopy, bullet-shaped particles (84 nm X 194 nm) characteristic of IHNV were observed. The data suggested that the Mayfly may be a factor in the dissemination of IHNV.

Salivary glands from males of 3 Dermacentor species (D andersoni, D variabilis and D occidentalis) that were infected with either the Virginia or Idaho isolate of Anaplasma marginale as nymphs or adults were examined for colonies of A marginale by use of light and electron microscopy. Prior to dissection of salivary glands, exposed ticks were held at 25 C for 15 to 18 days, followed by a 3-day incubation at 37 C. Ticks of 2 species transmitted A marginale to calves; the third tick species was confirmed infected by demonstration of typical colonies in tick gut cells, but transmission was not attempted; Colonies of A marginale were seen with light microscopy in salivary glands of all 3 species of ticks; they were located in acinar cells that contained simple granules. Colonies varied morphologically from small, compact ones to larger structures that contained distinct organisms and often were adjacent to the host cell nucleus. Electron microscopy confirmed that the colonies were rickettsial organisms. Morphologic features of A marginale varied and included reticulated forms, forms with electron-dense centers, and small particles; these various forms were similar to those described previously in midgut epithelial cells of ticks. We believe that the organism seen within tick salivary glands may replicate in the glands before its transmission to the vertebrate host.

Gas eructation function of the gastroesophageal sphincter (GES) was investigated in 6 conscious dogs before and after a sleeve was placed around the GES and gastric cardia and during IV infusion of a beta-adrenergic amine (epinephrine). To induce eructation, nitrogen gas was insufflated (351.4 +/- 2 ml/min; mean +/- SEM) into the stomach through 1 channel of a 4-lumen catheter. After baseline studies and epinephrine infusion studies were completed in each dog, surgery was done to limit partially gastric distension by intraluminal contents by placing a silicone rubber sleeve around the GES and the first few centimeters of the cardia. Gastroesophageal sphincter pressure was 31.8 +/- 2.2 mm of Hg in baseline studies, 17.3 +/- 1.3 mm of Hg during epinephrine infusion (P less than 0.003), and 30.3 +/- 2.2 mm of Hg after the sleeve was placed around the GES and cardia. During insufflation, gastric pressures before eructation increased to 5.74 +/- 0.41 mm of Hg before and to 15.15 +/- 1.63 mm of Hg after carida sleeve placement (P less than 0.001). Eructation occurred at intervals of 1.83 +/- 0.41 minutes before cardia sleeve placement, and eructations were not observed with the sleeve in place. Before the sleeve was placed, administration of epinephrine resulted in an eructation interval of 0.84 +/- 0.09 minutes, which was significantly different from that in the same dogs given no drugs (P less than 0.004). In vitro comparison of stomachs filled with fluid or filled with fluid and gas revealed that relatively small amounts of gas added to a partially filled stomach caused marked distension of the gastric cardia in comparison with no effects when fluid only was added. Seemingly, distension of the gastric cardia was the important stimulus for eructation. Limiting this distension prevented eructation and beta-adrenergic stimulation increased eructation frequency.

Intestinal lesions of transmissible gastroenteritis (TGE) virus infection in conventionally reared pigs suckling either nonvaccinated, vaccinated, or previously infected sows were studied by scanning electron microscopy, light microscopy, and immunofluorescent microscopy for TGE viral antigen. Pigs were inoculated with virulent TGE virus when they were 5 or 21 days old and were euthanatized shortly after the onset of diarrhea or 96 hours after inoculation if no diarrhea developed. Pigs inoculated when they were either 5 or 21 days old and suckling nonvaccinated sows developed severe lesions, including swelling and necrosis of enterocytes and severe villus atrophy. Pigs inoculated when they were 5 days old and suckling sows vaccinated with attenuated vaccines developed less-severe villus atrophy, and those suckling sows immunized by exposure to nonattenuated TGE virus developed moderate or no villus atrophy. Pigs inoculated when they were 21 days old and suckling sows vaccinated with attenuated vaccines had severe villus atrophy, whereas those suckling sows immunized by exposure to nonattenuated virus had more-moderate villus lesions. Villus atrophy was inhibited to various degrees in pigs suckling immunized sows, depending in part on the antibody titer in the colostrum and milk.

Effects of xylazine HCl (0.5 mg/kg of body weight, IV) and/or butorphanol tartrate (0.04 mg/kg, IV) or neostigmine methylsulfate (0.022 mg/kg, IV) on myoelectric activity of the cecum and right ventral colon were studied in 4 conscious female ponies. Eight bipolar Ag/AgCl electrodes were sequentially placed on the seromuscular layer of the cecum (6 electrodes) and right ventral colon (2 electrodes). Recordings began 30 minutes before and continued for 90 minutes after drug administration. Each drug or drug combination was studied on 2 occasions in each pony. Two major patterns of coordinated spike bursts were identified. A series of coordinated spike bursts began at the cecal base and was conducted to the cecal apex (pattern I). A series of coordinated spike bursts began at the cecal apex, traversed the cecum, cecocolic orifice, and right ventral colon and was termed a progressive pattern (pattern II). Xylazine administration caused a significant decrease in patterns I and II for 20 minutes (P less than 0.05). Butorphanol tartrate administration caused a significant decrease in the progressive pattern for 10 minutes (P less 0.05) without affecting the orally directed pattern. Administration of the combination of xylazine/butorphanol significantly decreased the frequency of pattern I for 40 minutes (P less than 0.05) and pattern II for 30 minutes (P less than 0.05). Neostigmine administration caused a significant increase in the frequency of pattern II for 30 minutes (P less than 0.05) without affecting pattern I (P greater than 0.05). Changes in conduction velocity of pattern I or II or the duration of spiking activity were not significantly different because of any treatment.

Experiments were conducted to establish a persistent Salmonella typhimurium infection in convalescent swine, and to determine rate of shedding and distribution of the organism in internal organs. Naturally farrowed Salmonella-free pigs (n = 37) were orally exposed to S typhimurium when 7 to 8 weeks old. Fecal samples, tonsillar scrapings, and rectal swab specimens were examined bacteriologically for S typhimurium at weekly intervals after exposure until necropsy (maximum of 28 weeks after exposure). Necropsies of 1 to 4 randomly selected pigs were conducted at 2, 4, and 7 days and at 2, 4, 6, 8, 12, 16, 20, 24, and 28 weeks after exposure. The following internal organs were examined bacteriologically for S typhimurium: liver, spleen, kidney, gallbladder, heart, lung, and stomach; segments of the intestinal tract with corresponding lymph nodes; lymph nodes from lymphocenters of the head and neck, thoracic and abdominal cavities, pelvic wall, and thoracic and pelvic limbs. Fecal samples were 83 to 100% culture-positive up to postexposure (PE) week 22, then varied from 14 to 67% positive until PE week 28. At least 60% of tonsillar swab specimens and 50% of rectal swab specimens were culture-positive up to PE week 20, after which they varied from 0 to 70% positive until PE week 28. At necropsy, S typhimurium was recovered most freguently from tonsils (93.5% positive), followed by segments of the intestinal tract from caudal portion of jejunum to rectum (71% recovery from cecum), and mandibular (54.8%) and ileocolic (45.2%) lymph nodes. The organism generally did not persist beyond PE week 2 in other lymph nodes of the head and neck, lymph nodes of the abdominal wall, thoracic cavity, or limbs, or in heart, liver, or spleen. The gallbladder, kidney, and lungs of all pigs were culture-negative.

Colostrum-deprived lambs (10 to 20 days old) were inoculated with either ovine adenovirus type 6 (OAV-6; n = 6), Pasteurella haemolytica type A1 (n = 6), or OAV-6 followed by P haemolytica 5 days later (n = 10). Another group (n = 3) served as sham-inoculated controls. Lambs inoculated with OAV-6 or P haemolytica developed mild and moderate respiratory tract disease of 6 and 3 days' duration, respectively. Lambs inoculated with virus and bacteria developed clinical signs of respiratory tract disease of greater intensity and duration (9 days) than with either agent alone. Within 3 hours of bacterial inoculation, all lambs that received P haemolytica were anorectic, listless, and febrile, and had hyperpnea and dyspnea. Ovine adenovirus type 6 was isolated from all virus-inoculated lambs. Although P haemolytica was not recovered from all bacteria-inoculated lambs, it was recovered for a longer period in the group that received both agents. Antibody to OAV-6 was detected in virus-inoculated lambs as early as day 6 after inoculation. The control lambs remained clinically normal and neither virus nor bacteria were recovered at necropsy.

Fecal samples from 131 cattle clinically suspect for paratuberculosis were cultured bacteriologically, using the traditional sedimentation processing method and a processing method that included a centrifugation step. Of 16 samples that were contaminated, 6 were culture-positive on at least 1 medium and by 1 processing method. Ten of 131 (7.6%) fecal samples processed by both methods were lost because of contamination. The number of culture-positive samples (using both processing methods) were 65 of 121 (53.7%) on media without miconazole and 60 of 121 (49.6%) on media with miconazole. Seven of the 121 (5.8%) samples were culture-positive, using centrifugation, after 16 weeks' incubation at 37 C. Thirteen of 60 (21.7%) isolates were obtained only with centrifugation, and 10 of these had low colony counts, suggesting that a centrifugation step may have concentrated microorganisms that would have gone undetected without centrifugation. Six of 60 (10%) isolates positive for M paratuberculosis on the sedimentation method were negative on the centrifugation method. Contamination rates were significantly (P less than 0.001) increased when centrifugation was used. The miconazole significantly (P less 0.001) decreased contamination rates when centrifugation was used.

Affinity-purified bovine immunoglobulin isotypes were bacteriolytic for Pasteurella haemolytica biotype A, serotype 1 (PHA-1). This bacteriolysis was specific and complement-dependent. The IgM and IgG1 were the most active isotypes in the classic complement cascade. These isotypes also induced bacteriolysis through the alternative complement cascade. The comparative bacteriolytic activities of IgG1 and IgM were equal within each cascade; however, the bacteriolytic activities of IgG1 and IgM were equal within each cascade; however, the bacteriolytic activities of IgG1 and IgM were lower in the alternative cascade than in the classical cascade. The IgG2 was more bacteriolytic than IgA in the classic and alternative complement pathways. Bovine immunoglobulins passively protected C57BL/6 mice from experimentally induced pasteurellosis. There were no major differences in the protection among hyperimmune sera, purified IgM, or purified IgG. Mice were protected from PHA-1 by approximately 1.9 microgram of IgG and 1.2 or 0.1 microgram of IgM. Elimination of murine complement with cobra venom factor 3 reduced PHA-1 clearance in passively immunized C57BL/6 mice. The protective effect of IgM mediated resistance was highly dependent on an intact complement system. The intact complement cascade was associated with enhanced clearance of PHA-1 from the liver. Although PHA-1 was susceptible to antibody complement-mediated bacteriolysis in vitro, the dependence on an intact complement cascade was not absolute in experimentally induced murine septicemic pasteurellosis.

Terminal renal dysfunction (TRD) was induced in 2 groups of dogs by partial surgical ablation of the kidney. Dogs of a control group and of 1 of the TRD groups were maintained on a diet containing normal phosphorus concentration, whereas dogs of the other TRD group were maintained on a low-phosphorus diet. Mild anemia developed in dogs of both TRD groups and could not be attributed to iron deficiency, increased erthrocyte concentration of 2,3-diphosphoglycerate, or absolute deficiency of erythropoietin (EP). Subsequently, all dogs were acutely depleted of approximately 25% of their blood volume. Erythropoietin concentration in dogs of the TRD groups was lower than that of controls, however, erythroid regenerative capacity was comparable with that of control dogs when plasma parathyroid hormone (PTH) concentration was lowered by reduced dietary intake of phosphorus. The PCV in dogs of the chronic TRD goups had a slight positive correlation with serum EP concentration, and a significant (P lesss than 0.05) negative correlation with plasma PTH and serum phosphorus and creatinine concentrations, using a correlation matrix. There was no longer a significant correlation between plasma PTH concentration and PCV after controlling for serum creatinine concentration by use of a multiple linear regression analysis. A significant (P less than 0.05) negative correlation also was observed between plasma PTH and serum EP concentrations, but not between serum EP and phosphorus or or creatinine concentrations. Significance of the EP and PTH association was reduced when analyzed, using a multiple linear regression analysis that included serum creatinine values. According to these data, PTH does have an independent effect on EP concentration, but the relationship between PTH and EP is not sufficiently strong to account for the genesis of the anemia of chronic TRD.