Monoclonal antibodies with neutralizing activity segregate isolates of bovine viral diarrhea virus into groups. Brief report.

Isolates of bovine viral diarrhea (BVD) virus were differentiated by monoclonal antibodies (MoAbs) reactive with the 56 kD viral polypeptide. Patterns of neutralizing activity of the MoAbs indicate that multiple epitopes are involved in virus neutralization.

Protection between different serotypes of bovine rotavirus in gnotobiotic calves: specificity of serum antibody and coproantibody responses.

In a previous study, different U.S. isolates of bovine rotavirus were studied for their serotypes and cross-protective properties (G. N. Woode, N. E. Kelso, T. F. Simpson, S. K. Gaul, L. E. Evans, and L. Babiuk, J. Clin. Microbiol. 18:358-364, 1983). Three viruses belonging to two different serotype groups were used as vaccines in gnotobiotic calves, which were subsequently challenged with B641 or B223, representing the two bovine serotypes. In the present work, the experiments were repeated with more calves and the specificity of their antibody responses was measured and compared with the results of the protection studies. Protection between different serotypes occurred under both homologous and heterologous conditions but was not directly serotype dependent. B223 virus showed both homologous and heterologous protection against B223 and B641 challenge viruses. This was a one-way reaction, as B641 did not induce protection against B223. Neonatal calf diarrhea virus vaccine produced neither homologous (against B641) nor heterologous (against B223) protection. The plaque reduction neutralization titers of serum antibody and coproantibody did not predict a state of protection against the challenge virus. Calves vaccinated with neonatal calf diarrhea virus or B641 developed neutralizing antibodies to their respective heterologous challenge viruses but were not protected. After challenge, the boosted coproantibody plaque reduction neutralization response to the original vaccine virus was greater than that to the challenge virus.

Serotypes of bovine astrovirus.

Three isolates of bovine astrovirus, one from the United Kingdom and two from the United States, possessed common antigens by immunofluorescence and strain-specific antigens by neutralization and were designated as two, and probably three, distinct serotypes. The isolate US2, despite being a different serotype, possessed the same restrictive cell tropism and cytopathology as previously reported for isolate US1, of the M cells of the dome epithelium of the Peyer's patches. Serotyping of 16 field isolates indicated the presence of more undefined serotypes.

Astrovirus and Breda virus infections of dome cell epithelium of bovine ileum.

A bovine enteric virus antigenically related to the United Kingdom isolate of bovine astrovirus was isolated from diarrheic feces, also containing rotavirus, of a calf in Florida. The astrovirus infected cell cultures and the epithelial cells of domes in the ileum, and there was cross-immunofluorescence with antiserum to the United Kingdom astrovirus. Calves infected with astrovirus alone did not develop clinical disease, but when astrovirus was mixed with rotavirus or Breda virus 2, the calves developed severe diarrhea and more extensive astrovirus infection of the dome epithelium. The dome epithelial cells showed degeneration associated with astrovirus infection, and a few cells showed degeneration with Breda virus 2 infection. Virions with a 30-nm diameter were seen in astrovirus-infected dome cells, and Breda virus 2 virions were also observed either in separate cells or, on occasion, with both viruses in one cell.