Isolation, identification, and comparison of four isolates of avian paramyxovirus serotype 2 in China.

Four Yucaipa-like viruses of avian paramyxovirus serotype 2 (APMV-2) were isolated in China from the imported Gouldian Finch (Chloebia gouldiae) and broilers in 1998-2002, and were named F4, F6, F8, and NK, respectively. Examined under electron microscope, the isolates were found to be round in shape and varying in size. The results of the hemagglutination inhibition test and indirect enzyme-linked immunosorbent assay (using monoclonal antibodies) showed some differences between the isolates and the reference strain Yucaipa. The isolates derived from chickens had a closer relationship to Yucaipa virus than did those of finches. Sequence comparison of the fusion gene and the haemagglutinin-neuraminidase gene showed similar results, although the variations were lesser among APMV-2 viruses in nucleotide and amino acid sequence. By sequence comparison, it was also revealed that at the molecular level the four virus strains belong to APMV-2, and that two of the strains were isolated from the same group of imported Gouldian Finches.