Our objectives were to describe the ultrastructural morphogenesis of pulmonary lesions induced by 3-methylindole in 30- to 45-day-old Holstein calves and to determine whether toxic exposure to 3-methylindole exacerbates pulmonary lesions induced by bovine respiratory syncytial virus. Administration of 3-methylindole (0.25 g/kg) to calves resulted in interstitial edema and ultrastructural swelling of type-I alveolar epithelial cells and nonciliated bronchiolar epithelial cells as early as 4 to 6 hours after intraruminal administration. More severe alveolar edema containing protein was associated with swelling of capillary endothelial cells at 2 days after administration. Proliferation of type-II alveolar epithelial cells was first observed at 2 days after 3-methylindole administration, and marked hyperplasia of type-II epithelial cells and nonciliated bronchiolar epithelial cells was evident by 4 days after administration. Pulmonary cytochrome P-450 monooxygenase concentrations decreased significantly (P < 0.001) by 12 hours after administration and did not increase significantly again by 8 days after administration. Calves were inoculated with bovine respiratory syncytial virus 3 days after administration of 3-methylindole, and pulmonary lesions were assessed 5 days after viral inoculation. Viral replication was demonstrated by fluorescence microscopy for viral antigen or by transmission electron microscopy in ciliated and nonciliated airway epithelial cells. Viral antigen was identified infrequently in alveolar macrophages and in type-II alveolar epithelial cells. 3-Methylindole exposure in calves did not result in more widespread distribution of viral antigen in alveolar tissue of respiratory syncytial virus-inoculated calves or in significant enhancement of viral pneumonia. The results indicated that young calves are susceptible to 3-methylindole-induced pulmonary injury and that nonciliated bronchiolar epithelial cells, type-I alveolar epithelial cells, and pulmonary endothelial cells are most susceptible to injury. The results failed to indicate that 3-methylindole pulmonary toxicosis significantly enhances respiratory disease induced by bovine respiratory syncytial virus.

The possible development of type-1 hypersensitivity reactions in the abomasal mucosa caused by soluble L3 products of Ostertagia ostertagi was studied in 4-month-old calves sensitized by repeated exposure to L3 over a 50-day period followed by anthelmintic treatment. Four groups each of 4 calves were used. Group 1 served as nonsensitized controls and group 2 as sensitized controls, group 3 was challenge exposed at 2-week intervals beginning at week 10 with a soluble L3 product (OAG), and group 4 was challenge exposed at 2-week intervals with an oral dose of L3, followed by anthelmintic treatment 3 days later. All calves infected with L3 became sensitized, as indicated by a positive reaction to an intradermal skin test. However, a passive cutaneous anaphylaxis was only partly effective in indicating the presence of homocytotropic antibody in the infected calves. Sensitized calves had significantly (P < 0.05) higher eosinophil counts and plasma pepsinogen values for the entire 14 weeks than uninfected controls. Globule leukocyte and mast cell counts from the abomasal mucosa were also significantly (P < 0.05) higher. Studies for possible immunomodulation revealed that lymphocyte counts decreased between every 2-week challenge-exposure period for groups-3 and -4 calves. A transient depression of blood lymphocyte (BL) responses to phytohemagglutinin (PHA), a T-cell mitogen, was observed over the first 8 weeks in the infected calves. Increases in BL responses to OAG were also observed. Differences were not observed in BL responses to pokeweed mitogen, a T- and B-cell mitogen. Blood lymphocyte responses to PHA in group-3 calves were low following the initial challenge exposure with OAG. The sensitized calf lymphocytes did not have suppressive activity on the response of control calf lymphocytes to PHA. Differences were not observed in lymphocyte responses to PHA in a suppressive assay done on abomasal lymph node lymphocytes. Increases in abomasal lymph node mass and lymphocyte responses to PHA, pokeweed mitogen, and OAG were observed in all sensitized calves. Histologic examination of abomasal lymph node sections from challenge-exposed calves revealed increased mitotic activity in germinal centers. Plasma pepsinogen values in groups 3 and 4 increased between each challenge exposure, which further suggested that type-1 hypersensitivity reactions had occurred in the abomasal mucosa, resulting in increased permeability and leakage of macromolecules.

Thirteen 3-week-old pigs that had been allowed to nurse for the first 16 to 18 hours after birth were orally inoculated with 1 X 10(6.5) TCID(50) of porcine rotavirus. All developed diarrhea, anorexia, and vomiting by postinoculation (PI) hour 30. These signs had abated by PI day 6. Villus blunting in the small intestine was most severe in the jejunum and ileum of pigs euthanatized between PI days 3 and 5. Villi had returned to nearly normal length by PI day 6, although fused villi were seen in a few locations in the distal portion of the jejunum and in the ileum. Virus was detected in the feces of inoculated pigs by isolation in cell cultures and by electron microscopy during the 7-day course of the experiment. There was 1 extraintestinal virus isolation from the lung of 1 pig at PI day 2. Infection and disease developed in the presence of serum-neutralizing antibody obtained by nursing seropositive sows. There was no significant change in neutralizing antibody titers in the 3-week-old pigs over the course of the experiment. In this experimental work, a model to study rotavirus infection in 3-week-old pigs has been developed.

To determine the phenotype of target cells for bovine leukemia virus (BLV) infection in sheep, we analyzed blood lymphocytes from BLV-infected clinically healthy and leukemic sheep by used of monoclonal antibodies. In clinically healthy and leukemic sheep that were BLV-infected, the blood concentration of T lymphocytes was within normal values, but the number of B lymphocytes was increased in several cases. In addition, the number of blood lymphocytes expressing the BLV antigen correlated well with that of B lymphocytes. Double immunofluorescence staining demonstrated that lymphocytes expressing BLV antigens bore B-cell but not T-cell surface markers. Moreover, neoplastic cells in the lymph nodes of leukemic sheep were stained immunohistochemically with an anti-B monoclonal antibody but not with any of anti-T monoclonal antibody tested, indicating that tumor cells are of B-lymphocyte origin. Collectively, these results show that BLV antigen-positive cells obtained from BLV-infected sheep that have no clinical signs and BLV-induced lymphosarcoma cells belong to the B-lymphocyte lineage.

Relative pathogenicity of 151 Escherichia coli isolates from 36 calves with bacteremia after necropsy was studied by measurement of the LD50 after mice were inoculated IP with E coli isolates. Study of virulence factors and markers revealed that the pathogenicity of E coli was associated with the production of hydroxamate siderophores and with resistance to serum bactericidal effects. Production of colicins, including colicin V, and of surface antigen 31A was correlated with virulence. The close association between phenotypic expression of virulence factors and markers was consistent with a hypothesis of a localization of genes coding for virulence factors and markers on the same plasmid.

Clinical signs of respiratory tract disease were observed in chickens that were inoculated intratracheally with 1 x 10(6) oocysts of Cryptosporidium baileyi at 2 or 14 days of age (10 chickens/group), but not in chickens inoculated at 28 or 42 days of age (10 chickens/group). Orally inoculated chickens in all age groups (10 chickens/group) did not develop clinical signs of disease. Orally and intratracheally inoculated chickens in all age groups were infected, as determined by the finding of cryptosporidia in tissue sections of the trachea, bursa of Fabricius, and cloaca, and by the recovery of oocysts from their feces. Chickens inoculated at 2 and 14 days of age excreted oocysts for a longer period and had greater numbers of cryptosporidia in their tissues, compared with chickens inoculated at 28 and 42 days of age.

In May of 2013, porcine epidemic diarrhea virus (PEDV) was detected in swine for the first time in North America. It spread rapidly, in part due to contaminated livestock trailers. The objective of this study was to test the efficacy of an accelerated hydrogen peroxide disinfectant for inactivating PEDV in the presence of feces on metal surfaces, such as those found in livestock trailers. Three-week-old barrows were inoculated intragastrically with 5 mL of PEDV-negative feces for the negative control, 5 mL of untreated PEDV-positive feces for the positive control, and 5 mL or 10 mL of PEDV-positive feces that was subjected to treatment with a 1:16 or 1:32 concentrations of accelerated hydrogen peroxide disinfectant for a contact time of 30 min at 20°C. These pigs served as a bioassay to determine the infectivity of virus following treatment. Rectal swabs collected from the inoculated pigs on days 3 and 7 post-inoculation were tested by using PEDV-specific real-time reverse transcription polymerase chain reaction and the proportion of pigs in each group that became infected with PEDV was assessed. None of the pigs used for the bioassay in the 4 treatment groups and the negative control group became infected with PEDV, which was significantly different from the positive control group (P < 0.05) in which all pigs were infected. The results suggest that the application of the accelerated hydrogen peroxide under these conditions was sufficient to inactivate the virus in feces found on metal surfaces.

Objective—To evaluate the ability of small interfering RNAs (siRNAs) to inhibit in vitro viral replication and gene expression of feline coronavirus (FCoV). Sample—Cell cultures of Crandell-Rees feline kidney cells. Procedures—5 synthetic siRNAs that each targeted a different region of the FCoV genome were tested individually and in various combinations for their antiviral effects against 2 strains of FCoV (feline infectious peritonitis virus WSU 79-1146 and feline enteric coronavirus WSU 79-1683) in cell cultures. Tested combinations targeted the FCoV leader and 3′ untranslated region, FCoV leader region and nucleocapsid gene, and FCoV leader region, 3′ untranslated region, and nucleocapsid gene. For each test condition, assessments included relative quantification of the inhibition of intracellular viral genomic RNA synthesis by means of real-time, reverse-transcription PCR analysis; flow cytometric evaluation of the reduction of viral protein expression in infected cells; and assessment of virus replication inhibition via titration of extracellular virus with a TCID50 infectivity assay. Results—The 5 siRNAs had variable inhibitory effects on FCoV when used singly. Combinations of siRNAs that targeted different regions of the viral genome resulted in more effective viral inhibition than did individual siRNAs that targeted a single gene. The tested siRNA combinations resulted in approximately 95% reduction in viral replication (based on virus titration results), compared with findings in negative control, nontargeting siRNA–treated, FCoV-infected cells. Conclusions and Clinical Relevance—In vitro replication of FCoV was specifically inhibited by siRNAs that targeted coding and noncoding regions of the viral genome, suggesting a potential therapeutic application of RNA interference in treatment of feline infectious peritonitis.

Encephalomyocarditis virus (EMCV) can infect many host species and cause acute myocarditis and sudden death in preweaned piglets. In this study, an EMCV strain (NJ08) was isolated from newborn pigs with clinical signs on a pig farm in mideastern China. It was identified by indirect immunofluorescence assay and reverse-transcription polymerase chain reaction. Experiments showed that the isolate could cause severe clinical symptoms and pathological changes in mice but no obvious clinical and pathological changes in commercial piglets. Complete genomic sequencing showed that the NJ08 strain was 78.3% to 100% identical with other isolates in regions coding for various proteins. Phylogenetic analysis showed that the NJ08 isolate belonged to subgroup Ia. This study confirmed that an EMCV isolate from pigs could be fatal to mice and provided new epidemiologic data on EMCV in China.

Objective—To evaluate whether an equine-derived canine H3N8 influenza A virus was capable of infecting and transmitting disease to ponies. Animals—20 influenza virus-seronegative 12- to 24-month-old ponies. Procedures—5 ponies were inoculated via aerosol exposure with 10(7) TCID50 of A/Canine/Wyoming/86033/07 virus (Ca/WY)/pony. A second group of 5 ponies (positive control group) was inoculated via aerosol exposure with a contemporary A/Eq/Colorado/10/07 virus (Eq/CO), and 4 sham-inoculated ponies served as a negative control group. To evaluate the potential for virus transmission, ponies (3/inoculation group) were introduced 2 days after aerosol exposure and housed with Ca/WY- and Eq/CO-inoculated ponies to serve as sentinel animals. Clinical signs, nasal virus shedding, and serologic responses to inoculation were monitored in all ponies for up to 21 days after viral inoculation. Growth and infection characteristics of viruses were examined by use of Madin-Darby canine kidney cells and primary equine and canine respiratory epithelial cells. Results—Ponies inoculated with Ca/WY had mild changes in clinical appearance, compared with results for Eq/CO-inoculated ponies. Additionally, Ca/WY inoculation induced significantly lower numbers for copies of the matrix gene in nasal secretions and lower systemic antibody responses in ponies than did Eq/CO inoculation. The Ca/WY isolate was not transmitted to sentinel ponies. Conclusions and Clinical Relevance—Inoculation of ponies with the canine H3N8 isolate resulted in mild clinical disease, minimal nasal virus shedding, and weak systemic antibody responses, compared with responses after inoculation with the equine H3N8 influenza isolate. These results suggested that Ca/WY has not maintained infectivity for ponies.