Isolation of a reovirus-like agent (rotavirus) from neonatal calf diarrhea in Japan

Development and application of one-step multiplex reverse transcription PCR for simultaneous detection of five diarrheal viruses in adult cattle

A one-step multiplex reverse transcription (RT)-PCR method was developed for the simultaneous detection of five viruses causing diarrhea in adult cattle: bovine group A rotavirus (GAR), bovine group B rotavirus (GBR), bovine group C rotavirus (GCR), bovine coronavirus (BCV), and bovine torovirus (BToV). The detection limit of the one-step multiplex RT-PCR for GAR, GCR, BCV, and BToV was 10², 10⁰, 10¹, and 10² TCID₅₀/ml, respectively, and that for GBR was 10⁶ copies/ml. The one-step multiplex RT-PCR with newly designed primers to detect GAR had higher sensitivity than a single RT-PCR with conventional primers, with no false-positive reactions observed for ten other kinds of bovine RNA viruses To assess its field applicability, 59 of 60 fecal samples containing one of these five viruses from all 25 epidemic diarrhea outbreaks in adult cattle were positive in the one-step multiplex RT-PCR assay. Furthermore, using four additional fecal samples containing two viruses (GBR and BCV or BToV), two amplified products of the expected sizes were obtained simultaneously. In contrast, all 80 fecal samples lacking the five target viruses from normal adult cattle were negative in the multiplex assay. Taken together, our results indicate that the one-step multiplex RT-PCR developed here for the detection of GAR, GBR, GCR, BCV, and BToV can be expected to be a useful tool for the rapid and cost-effective diagnosis and surveillance of viral diarrhea in adult cattle.

Passive protection against bovine rotavirus in calves by specific immunoglobulins from chicken egg yolk

The efficacy of chicken egg yolk immunoglobulins (yIg) from hens immunized with bovine rotavirus (BRV) serotype G6 (strain Shimane) or serotype G10 (strain KK-3) for protection against homologous BRV in calves was investigated. A significant protection by anti-BRV yIg having 6400 neutralizing antibody titer per dose could be achieved in calves (P < 0.01).

Passive protection against bovine rotavirus-induced diarrhea in murine model by specific immunoglobulins from chicken egg yolk

Chicken egg yolk immunoglobulins (yIg) specific against bovine rotavirus (BRV) serotypes 6 (strain Shimane) and 10 (strain KK-3) were used for oral passive immunization of suckling mice against experimental BRV challenge. The protective capacity of the antibody preparation was tested using different concentrations of yIg against a challenge dose of 10(7.5) TCID50 for Shimane and 10(7.0) TCID50 for KK-3 strain. There was a significant homotypic (P < 0.05) and heterotypic (P < 0.01) protection using 160 anti-Shimane or 160 anti-KK-3 neutralizing antibody titer (NAT) compared to control mice given yIg derived from eggs of mock-immunized (control) hens. The titer of infectious BRV recovered from intestinal tissue or luminal chyme decreased with increasing homotypic yIg NAT. A decrease in degree and duration of BRV antigen localization in the villus epithelial lining was observed in mice treated with homotypic yIg at optimum dose for prevention of diarrhea. The NAT in sera of challenged mice increased with decreasing NAT in the yIg given before challenge suggesting that protection was dose-dependent. The present findings indicate that a passive protection could be achieved by the use of yIg against BRV-induced diarrhea in this murine model.

Detection of bovine coronavirus in feces by reversed passive hemagglutination

A reversed passive hemagglutination (RPHA) method was developed for the detection of bovine coronavirus in fecal specimens. Sheep erythrocytes fixed with glutaraldehyde, and then treated with tannic acid were coated with anti-bovine coronavirus rabbit antibodies purified by affinity chromatography using bovine coronavirus linked to Sepharose 4B. The RPHA test was carried out by a microtiter method. Erythrocytes coated with purified specific antibodies were agglutinated by bovine coronavirus, but not by bovine rotavirus or enterovirus. The reaction was inhibited by antiserum to bovine coronavirus, confirming the specificity of the reaction. The RPHA test detected bovine coronavirus in 13 of 22 fecal specimens (59 per cent), from natural cases of diarrhea, while the positive rates were only 14 per cent (3/22) and 22 per cent (5/22) for immunofluorescent staining of primary cultures of calf kidney cells infected with the specimens, and immune electron microscopy respectively. The advantages of the RPHA method are its simplicity, high sensitivity and rapidity.

Isolation of new serotypes of bovine rotavirus. Brief report

Two cytopathogenic bovine rotavirus strains were isolated. The infectivity of both isolates was relatively stable at pH 3.0 and resistant to ether. Their replication was not affected by 5-iodo-2'-deoxyuridine. The new isolates shared immunofluorescent antigen with the Lincoln strain of bovine rotavirus. By neutralization test, however, these strains were clearly distinguished from one another.

Epizootic diarrhoea of adult cattle associated with a coronavirus-like agent

An epizootic of acute diarrhoea of adult cattle occured in Japan during the winter of 1976 to 1977. A majority of adult cattle clinically diagnosed as having the disease, showed a significant rises in antibody titres to bovine coronavirus, whereas only a smal; minority showed serological evidence of recent infection with calf rotavirus, bovine adenovirus type 7, parainfluenza virus type 3, or bovine viral diarrhoea-mucosal disease virus. A coronavirus-like agent was detected by electron-microscopy in faecal material from a cow with diarrhoea, and was subsequently isolated in primary bovine kidney cell cultures.