Evaluation of the protection conferred by several avian infectious bronchitis attenuated vaccines against the field strain CK/CH/LDL/97 I in China / 病毒学报

The entire S1 protein gene of five infectious bronchitis (IB) vaccine strains (JAAS, IBN, Jilin, J9, H120) used in China were compared with that of the IB field isolate CK/CH/LDL/97 I present in China. The nucleotide and deduced amino acid similarities between the five IB vaccine strains and the field strain, CK/CH/LDL/97 I, were not more than 76.4% and 78.7%, respectively. Phylogenetic analysis based on the S1 gene showed that the vaccine strains and the field strain belonged to different clusters and had larger evolutionary distances, indicating that they were of different genotypes. The five vaccine strains were used for protection test against challenge of the field isolate CK/CH/LDL/97 I. The chickens inoculated with five vaccine strains showed morbidity as high as 30%-100% after challenged with the CK/CH/ LDL/97 I strain. The organ samples at 5 days post challenge showed that the viral detection rates were 50%-90% and 10%-30% for trachea and kidney, respectively. The live attenuated vaccines only provided partial protection to the vaccinated chickens against heterologous IBV infection, CK/CH/LDL/97 I.

Isolation and identification of A reovirus from masked civet cats (Paguma Larvata) / 病毒学报

192 samples of Masked Palm Civet (Paguma Larvata) from Guangdong Province were inoculated in Vero-E6 cells. One sample which came from masked palm Civet didn't cause cytopathic effects (CPE) until fourth-passage on Vero-E6 cells. Infected cells emerged granulating, shrinking, rounding and falling off. After three times freeze-thaw, cells and culture medium were harvested for electron microscopy. Virus particles were nonenveloped, double capsid and icosahedral symmetry. This virus was designated Masked Palm Civet/China/2004 (MPC/04). Hemagglutination test indicated that the virus could agglutinate healthy human type O red cells, but not the red cells of SPF chicken, experimental common bovine, rat and guinea pig. This virus was tolerant to chloroform treatment, pH 3.0 and water bath 50 degrees C 1 h. 1 M MgCl2 treatment could enhance resistance of virus to heat and increase infectivity. In order to classify the strain on the molecular level, specific primers according to mammalian reovirus were used for Reverse Transcription Polymerase Chain Reaction (RT-PCR). Appropriate specific products were amplified by RT-PCR. NCBI BLAST analysis indicated that this segment shared the highest identity to mammalian reovirus serotype 1 (T1L) virus. So we can deduce this virus is a member of the Reoviridae.

Genetic variations of membrane gene of infectious bronchitis virus strains isolated in China between 1995 and 2004 / 病毒学报

Membrane (M) protein genes of 20 infectious bronchitis virus (IBV) strains isolated in China between 1995 and 2004 were sequenced and analyzed. The M genes of twenty isolates were composed of 672 to 681 nucleotides, encoding polypeptides of 223 to 226 amino acid residues. Variations of the deduced amino acids of M gene mainly occurred at positions 2 to 17 and 221 to 233, comparing with that of the IBV strain LX4. There were deletions or insertions in the M gene of Chinese isolates at amino acid position 2 to 6, leading to the loss or gain of a glycosylation site. Phylogenetic tree based on amino acid sequences of M genes from 20 Chinese isolates and 34 reference strains showed that they were classified into five distinct clusters. Most of the Chinese IBV strains were included in clusters II and IV, forming distinct groups. The isolates in cluster II showed a close evolutionary relationship with Taiwan isolates. Furthermore, recombination especially the recombination between field isolates and vaccine strains had been observed while comparing the phylogeny of M genes with those of S1 and N genes.