In recent years, enterovirus 71 (EV71) has been a cause of numerous outbreaks of hand-foot-and-mouth disease, with severe neurological complications in the Asia-Pacific region. The reemergence in Taiwan of EV71 genotype B5 in 2008 resulted in the largest outbreak of EV71 in Taiwan in the past 11 years. Phylogenetic analyses indicated that dominant genotype changes from B to C or C to B occurred at least three times between 1986 and 2008. Furthermore, antigenic cartography of EV71 by using neutralization tests revealed that the reemerging EV71 genotype B5 strains formed a separate cluster which was antigenically distinct from the B4 and C genotypes. Moreover, analyses of full-length genomic sequences of EV71 circulating in Taiwan during this period showed the occurrence of intra-and interserotypic recombination. Therefore, continuous surveillance of EV71 including the monitoring of genetic evolution and antigenic changes is recommended and may contribute to the development of a vaccine for EV71.The genus Enterovirus ([EV] family Picornaviridae) contains numerous viruses that are pathogenic to humans. Human EVs (HEVs) have been classified into four species, HEV-A, HEV-B, HEV-C, and HEV-D, based on their sequence homologies (48). In contrast to other etiological agents of hand-foot-and-mouth disease that tend to cause mild and self-limiting disease, EV71 infection is often associated with other clinical manifestations including acute neurologic symptoms, such as poliomyelitis-like paralysis, encephalitis, aseptic meningitis, shock, and cardiac dysfunction (32).Since 1969, when EV71 was first isolated in California, EV71-associated outbreaks have been reported worldwide (42). EV71 infection reached epidemic proportions, causing sporadic cases or outbreaks and then becoming prevalent around the AsiaPacific region including Australia, Malaysia, Singapore, Japan, China, and Taiwan for the past 12 years (1, 16-18, 20, 25, 26, 28, 46, 53). Phylogenetic studies have classified EV71 into genotypes A, B, and C, which can be further subdivided into subgentotypes B1 to B5 and C1 to C5 (7,8,17,20,22,25,28,41,45,52,53). These reports indicated that the dominant EV71 strains circulating in the Asia-Pacific region varied genetically, suggesting that the virus was evolving.Intertypic or intratypic recombination of EV71 has been reported to occur frequently in the region encoding the nonstructural proteins and could potentially influence the replication, tissue tropism, and virulence of EV71 (10,11,18). These studies emphasized the importance of full-genome sequencing for the surveillance of EV71 evolution. Therefore, to analyze the evolution of EV71, we performed phylogenetic analysis of the Taiwan isolates from 1986 and from 1998 and 2008 based on the complete genomic sequences. In addition, neutralizing activities of human antiserum against the various subgenotypes of EV71 were investigated to evaluate the antigenic changes of EV71. We found evidence for intertypic and intratypic recombination and demonstrated variation in anti...

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Influenza viruses cause pandemics in humans. The aim of this study was therefore to evaluate filter/real-time qPCR to quickly and accurately determine and quantify the airborne influenza and avian influenza virus. In this study, the sampling stress of filtration to influenza virus and the storage effects for both the virus and extracted RNA were evaluated in the laboratory. Then, the collection efficiencies of open-face and closed-face filter cassettes were compared in a wet poultry market. From July 8 to August 19, 2006, a total of 36 air samples were quantified by filter/real-time qPCR.The recovery rate of the virus on a filter stored at 4• C reached 0.94 after 3-day storage, whereas the RNA stored at -80• C was 100% after 3-month storage. In terms of collection efficiency, the closed-face filter cassette was superior to the open-face filter cassette in the field study. In the wet poultry market, it was revealed that both the positive rate and concentration of influenza A virus in the chicken pen were higher than that in the duck pen, possibly due to differences in ventilation type, climate factors, and avian characteristics. To our knowledge, this is the first report describing the quantification of airborne influenza virus in field samples. This quantitative technique should provide more insight into influenza/avian influenza virus transmissibility and epidemiology of influenza/avian influenza, as well as infection control.

In Taiwan, enterovirus 71 (EV71) has played an important role in severe enterovirus-related cases every year since the devastating outbreak in 1998. Three genogroups A, B, C occur worldwide; with the B and C genogroups being subdivided into B1-B4 and C1-C4 subgenogroups respectively. To understand the mutation of the EV71 genogroup in Taiwan before and after 1998, a total of 54 worldwide strains were studied including 41 Taiwanese strains obtained in 1986 and 1998-2004. A fragment of 207 bp of the VP4 region was amplified and sequenced. Genetic analysis was performed using MEGA software (version 3.0) for the nucleotide sequence alignment and phylogenetic analysis. In Taiwan, the subgenogroup B1 was predominant before 1998 while subgenogroup C2 was the major etiologic group in 1998 outbreak. A minor etiologic group outbreak in 1998, subgenogroup B4, became predominant during the period from 1999 to 2003. In this study, subgenogroup C4 emerged and became predominant in 2004 in Taiwan. The nucleotide differences between B1 and C2, C2 and B4, B4 and C4 were 20%-26%, 19%-27%, 18%-22%, respectively. Nucleotide sequence alignment revealed 67 substitutions. Most of the substitutions (62/67) were silent mutations. This is the first report about the emergence of EV71 subgenogroup C4 in Taiwan.

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