Generation and evaluation of reassortant influenza vaccines made by reverse genetics for H9N2 avian influenza in Korea.
The prevalence and continuous evolution of H9N2 avian influenza viruses in poultry have necessitated the use of vaccines in veterinary medicine. Because of the inadequate growth properties of some strains, additional steps are needed for producing vaccine seed virus. In this study, we generated three H9N2/PR8 reassortant viruses using a total cDNA plasmid-transfection system, as an alternative strategy for developing an avian influenza vaccine for animals. We investigated the vaccine potency of the reassortant viruses compared with the existing vaccine strain which was adapted by the 20th serial passages in embryonated eggs with A/Ck/Kor/01310/01 (H9N2). The H9N2/PR8 reassortant viruses, containing the internal genes of the high-yielding PR8 strain and the surface gene of the A/Ck/Kor/01310/01 strain, could be propagated in eggs to the same extent as existing vaccine strain without additional processing. Similar to vaccine strain, the H9N2/PR8 reassortant viruses induced hemagglutination-inhibiting antibodies in chickens and prevented virus shedding and replication in multiple organs in response to homologous infection. However, due to the continuing evolution and increasing biologic diversity of H9N2 influenza in Korea, the vaccine provided only partial protection against currently isolates. Taken together, our results suggest that the H9N2/PR8 reassortant virus can be used as a seed virus for avian influenza vaccines in poultry farm. Considering the constant genetic changes in H9 strains isolated in Korea, this reverse genetic system may offer a prompt and simple way to change the vaccine seed virus and mitigate the impact of unexpected influenza outbreaks.
Song
Jae Min
JM
National Veterinary Research & Quarantine Service, Anyang6dong, Manangu, Anyang City, Gyeonggi-do 430-824, Republic of Korea.
Lee
Youn Jeong
YJ
Jeong
Ok Mi
OM
Kang
Hyun Mi
HM
Kim
Hye Ryoung
HR
Kwon
Jun Hun
JH
Kim
Jae Hong
JH
Seong
Baik Lin
BL
Kim
Yong Joo
YJ
D000818:Animals; D001717:Birds; D002645:Chickens; D053127:Influenza A Virus, H9N2 Subtype / Q000235:genetics*; D007252:Influenza Vaccines / Q000276:immunology*; D005585:Influenza in Birds / Q000453:epidemiology* / Q000276:immunology*; D007668:Kidney / Q000821:virology; D007723:Korea / Q000453:epidemiology; D008168:Lung / Q000821:virology; D010063:Ovum / Q000821:virology; D014066:Palatine Tonsil / Q000821:virology; D016865:Reassortant Viruses / Q000235:genetics*; D013047:Specific Pathogen-Free Organisms; D013154:Spleen / Q000821:virology; D014132:Trachea / Q000821:virology
D007252:Influenza Vaccines