分子生物学方法在儿童流行性感冒监测中的应用

Application of molecular biological techniques in the surveillance of influenza viruses in infants and young children

目的 建立一种能够快速、特异、有效地直接从临床标本中检测流行性感冒 (流感 )病毒并进行病毒型和亚型鉴别的方法 ,同时了解近年来北京地区A3型流感病毒血凝素重链 (HA1)区基因的变异特点。方法 根据编码A、B型流感病毒膜蛋白M基因的核苷酸序列设计两对引物 ,用于同一逆转录 (RT) PCR反应中 (多重RT PCR) ,根据A、B型毒株扩增产物的大小 (分别为 5 0 6bp和2 61bp)鉴别A、B型流感病毒。另根据编码A1 和A3型流感病毒糖蛋白HA基因的核苷酸序列设计两对引物 ,与B型M基因引物用于同一RT PCR反应中 ,可区分A1 、A3或B型流感病毒 (扩增产物分别为 944bp、10 72bp和 2 61bp)。为提高检测临床标本的敏感性 ,针对A1 和A3型病毒HA基因和B型病毒M基因又设计了 3对引物作为外侧引物 ,进行巢式 PCR反应。根据第二次PCR的扩增产物在 1.2 %的琼脂糖凝胶电泳中的大小即可确定型别。经PCR扩增 1996～ 2 0 0 2年间分离的北京地区A3型流感病毒株HA1区基因 ,测序并进行序列分析。结果 用上述多重RT PCR鉴定流感病毒分离株 15 6株 ,与血凝抑制试验阳性符合率为 10 0 %。用多重巢式 PCR检测 92份已经病毒分离确定为流感的儿科临床呼吸道标本 ,与病毒分离和血凝抑制试验阳性符合率分别为 76.9% (A1 型 )、5 7.1%(A3型 )、

Objective To establish a rapid, specific and effective technique for identifying subtyping A 1,A 3 and B of influenza virus isolates and clinical specimens as well as to analyze the sequences of nucleotides and deduced amino acids of HA1 regions from isolates of influenza virus A 3 isolated from 1996 to 2002. Methods Six inner and outer sets of oligonucleotide primers were designed to detect, type and subtype human influenza A and B. The first two corresponding sets differatiate type A and B of matrix (M) gene while, the second two corresponding sets identify the H 1 and H 3 subtypes of type A virus HA gene. To type and subtype influenza viruses in clinical isolates, a mixture of inner primer sets specific for H 1, H 3 and B were used in a single PCR reaction tube. To detect influenza viruses in clinical specimens, a mixture of the outer primer sets were used in a single primary PCR tube, and the inner ones in a single second PCR reaction tube. Amplified products were visualized in 1.2% agrose gel containing ethidium bromide. HA1 regions of hemagglutinin of 5 field strains (H3N2) isolated from 1996 to 2002 in Beijing were amplified by RT-PCR and sequenced directly. Results There was 100% correlation between multiplex RT-PCR and culture to type and subtype influenza viruses from clinical isolates. For typing and subtyping, 76.9%, 57.1% and 86.5% were positive for A 1, A 3 and B by multiplex nested-PCR compared withn virus isolation on culture, respectively. The sequence data of HA1 of A 3 strains showed that there was a high homology of nucleotide and amino acid, and the closer the date of isolating was, the higher homology showed. Conclusions Multiplex RT-PCR and nested-PCR for influenza viruses could provide a useful alternative to existing methods of influenza detected and identified from clinical isolate and specimens. There were certain, continuous mutations and increasing glycosylated sites which might cause the antigen drift in the A 3 strains during 1996-2002 in Beijing area.