| Along with the development of etiological detection and identification technology in recent years, the important role of enterovirus (EV) in respiratory infectious diseases is drawing wider attention. There are varied types of EV infection distributed in4species of A, B, C and D, with over100genotypes (serotypes) discovered by far. The simultaneous epidemic of multi-genotypes usually leads to frequent inter-serotypic recombination. In addition, RNA dependent RNA polymerase lack of proofreading function often causes genome mutation. Recombination and mutation in genome cause the outbreak of EV. The etiology and epidemic spread of respiratory infection (RTI) caused by EV haven’t been clarified by far, which brings some difficulties to the monitoring and warning of EV-associated outbreaks. In view of this, based on the first report of the detection of EV68, a new variant, among adults with RTIs in2006and the separation of relevant strains, this study further assessed the infection of EV68in China by means of seroepidemiology and analyzed the features of recombination of EV species A of high detection rate in accordance with global epidemic trend.By using the method of serotype micro-neutralization test, a cross-sectional survey was given on the sero-prevalence of all age groups in Beijing area in2004and2009, the result suggested that the geometric mean titer (GMT) of EV68neutralizing antibody in2009was significantly higher than that in2004. This indicated that EV68infection had occurred during this phase coincide with the fact that there were more EV68detections in2006. In order to find out the variation trend of neutralizing antibody, this paper further carried out study on the serotypes of non-EV infected patients among acute respiratory infected adults in different years. The result showed that from2006to2011, GMT of EV68among adults increased year by year, indicating a progressive epidemic spread of EV68since2006. However, the low detection rate of EV68among clinic cases since2006suggested that the epidemic of EV68was mainly in form of symptomless or subclinical infection, and the emergence of neutralizing antibody effectively blocked its epidemic spread. This example also proves that the combination of etiological detection and seroepidemiological study could contribute to the accurate assessment of epidemic spread situation of specific virus.In our pervious etiological study of EV revealed that EV-A took a high detection rate in patients with RTIs with simultaneous epidemic of7types of this species. Because several serotypes of the same species could occur recombination in same host, we amplified the genome of these EV-As to analysis if they had recombination by setting up phylogenetic tree and giving phylogenetic analysis on genomic region VP1and2C of EV. It was discovered that40clinic strains respectively belonging to6serotypes and EV71strains located in the same clade, indicating a relative similarity between the clinic strains and EV71reference strain in genomic region2C. Further recombination analysis by SimPlot on whole genome sequences showed the clinic strains of all6serotypes (CVA2, CVA4, CVA6, CVA8, CVA10and CVA12) had recombination with EV71in non structural protein region. These strains represented54.79%of all detected EV-As. Above result suggests that the recombination between serotypes of EV-A and EV71is a universal phenomenon. As the major pathogen for hand-foot-mouth disease in recent years, EV71also has possibly contributed to the epidemic of EV-A in respiratory infection through its recombination with EV-A strains as genetic donor.The above study results to some extent illustrated the role of EV in respiratory infection and the epidemic spread situation of major types of EV, providing a basis for diagnosis, monitoring and warning of relative infectious diseases.
|
PDF Full Text Request