Generation and characterization of a cold-adapted attenuated live H3N2 subtype influenza virus vaccine candidate.
BACKGROUND
H3N2 subtype influenza A viruses have been identified in humans worldwide, raising concerns about their pandemic potential and prompting the development of candidate vaccines to protect humans against this subtype of influenza A virus. The aim of this study was to establish a system for rescuing of a cold-adapted high-yielding H3N2 subtype human influenza virus by reverse genetics.


METHODS
In order to generate better and safer vaccine candidate viruses, a cold-adapted high yielding reassortant H3N2 influenza A virus was genetically constructed by reverse genetics and was designated as rgAA-H3N2. The rgAA-H3N2 virus contained HA and NA genes from an epidemic strain A/Wisconsin/67/2005 (H3N2) in a background of internal genes derived from the master donor viruses (MDV), cold-adapted (ca), temperature sensitive (ts), live attenuated influenza virus strain A/Ann Arbor/6/60 (MDV-A).


RESULTS
In this presentation, the virus HA titer of rgAA-H3N2 in the allantoic fluid from infected embryonated eggs was as high as 1:1024. A fluorescent focus assay (FFU) was performed 24-36 hours post-infection using a specific antibody and bright staining was used for determining the virus titer. The allantoic fluid containing the recovered influenza virus was analyzed in a hemagglutination inhibition (HI) test and the specific inhibition was found.


CONCLUSIONS
The results mentioned above demonstrated that cold-adapted, attenuated reassortant H3N2 subtype influenza A virus was successfully generated, which laid a good foundation for the further related research.
An
Wen-qi
WQ
College of Animal Science and Veterinary Medicine, Jilin University, Changchun, Jilin, China.
Yang
Peng-hui
PH
Duan
Yue-qiang
YQ
Luo
De-yan
DY
Tang
Chong
C
Jia
Wei-hong
WH
Xing
Li
L
Shi
Xin-fu
XF
Zhang
Yu-jing
YJ
Liu
Xiu-fan
XF
Wang
Xi-liang
XL
D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D004285:Dogs; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000235:genetics; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D009439:Neuraminidase / Q000235:genetics; D010957:Plasmids; D016865:Reassortant Viruses / Q000276:immunology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014613:Vaccines, Attenuated / Q000276:immunology; D014764:Viral Proteins / Q000235:genetics
D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines; D014613:Vaccines, Attenuated; D014764:Viral Proteins; C487630:NA protein, influenza A virus; D009439:Neuraminidase