[Aetiologic study on the outbreaks of influenza-like disease in Shenzhen]

During March to May in 1994, the outbreaks of influenza like disease occurred in Shenzhen city. The outbreaks were caused by influenza B virus demonstrated by aetiologic and serological studies. The antigenic analysis indicated that the isolates were antigenically similar to B/Shanghai/1/93 and B/Guangdong/8/93 strains (both are B/Victoria/2/87. like virus). The genetic analysis showed that the HA1 genes of the isolates were 1038 nucleotides in length coding for HA1 protein of 346 amino acids which were same as those of B/Shanghai/1/93 virus and that the homogeneity of amino acid sequence on HA1 protein between isolates and B/Shanghai/1/93 virus was as high as 95%. These results further demonstrated that the isolates were B/Victoria/2/87 like strains. Meanwhile, this paper also revealed that the two antigenically distinct genetic lineages of influenza B virus were cocirculating in human population.