ABSTRACT
Objective To analyze the resistance of influenza virus to neuraminidase inhibitors (NAI) in Henan province during 2017-2018. Methods Virus were collected from the Henan Influenza Surveillance Network during 2017-2018. 36 confirmed influenza virus(with 15 H1pdm09，6 H3N2 and 15 B) were selected to test resistance to oseltamivir and zanamivi with fluorescence(FL). The NAI sensitive reference viruses were A/California/12/2012(H1pdm09)-275H,A/Beijing Haidian/1942/2014(H3N2)-119E and B/Rochester/02/2001-198D. The NAI resistant reference viruses were A/ Texas/23/2012(H1pdm9)-H275Y, A/Texas/12/2007(H3N2)-E119V and B/Rochester/02/2001-D198N. Results The half maximal inhibitory concentration(IC50) of A/California/12/2012(H1pdm09)-275H, A/Beijing-Haidian/1942/2014(H3N2)-119E and B/Rochester/02/2001-198D for oseltamivir were 0.29 nmol/L (nM),0.10 nM and 12.71 nM, and for zanamivir were 0.2 nM, 0.49 nM and 0.33 nM respectively. The IC50 for oxastatin of H1pdm09 and H3N2 ranged from (0.28-1.37 nM) and (0.08-0.17 nM) respectively, the IC50 for zanamivir ranged from (0.15-0.49 nM) and (0.12-0.22 nM), all was within 10 fold IC50 of the reference virus(corresponding type); the IC50 value of type B for oseltamivir and zanamivir ranged from (11.83-24.59 nM) and (0.48-1.25 nM), all was within 5 fold IC50 of the reference virus. Conclusion All the tested influenza strains isolated in Henan province during 2017-2018 were sensitive to NAI.
ABSTRACT
This study aims to investigate the genetic characteristics of hemagglutinin in wild-type measles viruses in Henan Province, China and to provide a basis for measles control and elimination. Specimens were collected from suspected measles cases in Henan during 2008-2012. Cell culture was performed for virus isolation, and RT-PCR was used to amplify hemagglutinin gene. The PCR products were sequenced and analyzed, including construction of phylogenetic tree and analysis of the distance between the isolated virus and the reference virus; then, the variations in predicted amino acids were analyzed. The results showed that 12 measles viruses were isolated in Henan Province and identified as H1a genotype; the nucleotide and amino acid homologies were 98.0%-100% and 97.2%-99.8%, respectively. One glycosylation site changed in all the 12 sequences because of the amino acid mutation from serine to asparagine at the 240th site, as compared with Edmonston-wt. USA/54/A. Overall, the wild-type measles virus genotype circulating in Henan Province from 2008 to 2012 was H1a, with high homology between strains; there were some variations in amino acid sequences, resulting in glycosylation site deletion.