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Objective@#To understand the viral etiology of a clustered case of human infection outbreak in the middle school of Huai’an city.@*Methods@#Nasopharyngeal swab samples from patients were collected and rapidly detected by Real-time RT-PCR and the target virus isolated in cells. Furthermore, HA1 segments of target virus were amplified by RT-PCR and sequenced. The genetic and phylogenetic analysis based on HA1 genes was computed.@*Results@#Influenza A(H1N1)pdm09 viral nucleic acid in 11 nasopharyngeal swab samples from patients in the outbreak were positive. Compared to the vaccine strains A/California/07/2009, the Huai’an isolates, nucleotide identity was 97.7%-98.1%, and amino acid identity was 96.6%-97.4%. Phylogenetic analysis of HA1 segment sequences indicated that the Huai’an strains from the outbreak were related closely to the viruses isolated in the year of 2014. Sequence analysis indicated that the Huai’an isolates had no amino acid substitution in the receptor binding sites and glycosylation sites, while in the Ca1 of antigenic determinant of HA1 the Huai’an isolates had an amino acid substitution of S for T at 220.@*Conclusions@#The pathogen of the clustered case of human infection was Influenza A(H1N1)pdm09 virus. Though the Huai’an isolates had one animo acid substitution in the Ca1 of antigenic determinant, the antigenicity characteristic remained unchanged.
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Objective To establish a novel method by integrating immunomagnetic bead enrich-ment with immunochromatography for the detection of influenza A virus. Methods The immunomagnetic beads were prepared by using EDC/NHS method and then coupled with monoclonal antibodies against influ-enza A virus. A direct immunomagnetic beads-based immunochromatography for the detection of influenza A virus was developed by using double-antibody sandwich method and immunochromatography, which was fur-ther combined with immunomagnetic separation to establish the novel integrated method of immunomagnectic bead enrichment and immunochromatography. Clinical throat swab samples collected from patients with influ-enza A virus infection and healthy subjects were analyzed by the novel method and the results were compared with those by using the conventional colloidal gold immunochromatography to evaluate the specificity, sensi-tivity and positive coincidence rate of this established method. Results The direct immunomagnetic beads-based immunochromatography and the colloidal gold immunochromatography showed no significant differences in specificity and sensitivity and could be used to identify influenza A virus-positive samples with cycle threshold ( Ct) values less than or equal to 22 obtained by real-time PCR assay. The integrated method could identify positive samples with Ct values less than or equal to 28, indicating that the novel method was more sensitive. Conclusion The novel method by integrating immunomagnetic bead enrichment with immunochroma-tography was successfully established and suitable for the rapid and on-site detection of influenza A virus.