一株鸡传染性贫血病毒野毒株致病性及其全基因组序列比较

Pathogenicity and genomic sequence comparison of a chicken infectious anemia virus field isolate

从山东某商品代肉鸡场表现生长迟缓的14日龄病鸡群分离到一株鸡传染性贫血病毒（CAV）C14株。C14株感染1日龄SPF鸡能抑制对禽流感病毒（AIV）的抗体反应,还能与禽网状内皮增生病病毒（REV）在免疫抑制上起协同作用。用PCR方法分段扩增出C14基因组的三条部分重叠片段,分别克隆于T载体并进行测序,拼接后得到其全基因组序列。测序结果表明,CAV-C14株基因组全长2298bp,含有3个互相重叠的开放阅读框和1个调控区。将C14与国内外已发表的CAV参考株基因组比较,同源性为97.2%~99.2%。序列比较表明CAV非编码区中含有的多个与复制及转录调控相关已知基序的序列都非常保守。CAV的3个编码基因VP1、VP2和VP3均有一定程度变异,以VP1变异性最大,且不同毒株间的3个蛋白质氨基酸序列的变异是互不相关的。

A field strain C14 of chicken infectious anemia virus （CAV） was isolated from a 14 day-old broiler flock with growth runting syndromes. Antibody reactions to inactivated vaccines to avian influenza viruses （AIV） were suppressed in SPF chickens inoculated with C14 strain CAV at 1 day-old. Also C14 strain CAV and reticuloendotheliosis Virus demonstrated a synergism in immunosuppression when chickens were infected with both virus. The viral genomic DNA was amplified by PCR in 3 overlapped fragments and PCR products were cloned into T-vector plasmid for sequencing. The sequencing results indicated that the total genome of C14 strain CAV was 2298bp, it contained 3 overlapped ORF and 1 non-coding regulation fragment. Its whole genome had 97.2%-99.2% of homogeneity to other several published CAV reference strains. Sequence data indicated that there are many motifs in the non-coding area of about 400bp as the binding sites for transcriptional factors. All these motifs were very conservative. There were some mutations in 3 genes VP1, VP2 and VP3. Relatively, VP1 was less conservative than VP2 and VP3. Among different strains, mutations in these 3 genes were not correlated.