Current Status of Live Attenuated Influenza Vaccine in the United States for Seasonal and Pandemic Influenza

Christopher S. Ambrose; Catherine Luke; Kathleen Coelingh


Influenza Resp Viruses. 2008;2(6):193-202. 

In This Article

Pandemic LAIV for Other Avian Influenza Subtypes

Pandemic LAIV viruses for use against the avian influenza subtypes H9N2 and H7N3 have been generated and characterized in preclinical studies. An H9N2 influenza vaccine virus, which derived the HA and NA from the low pathogenicity avian influenza isolate A/chicken/Hong Kong/G9/1997 (H9N2), was generated by classical reassortment. The H9N2 ca vaccine virus did not exhibit a high pathogenicity phenotype in chickens, was restricted in replication in the upper respiratory tract of mice, and failed to replicate to detectable levels in the lower respiratory tract of mice. Despite being restricted in replication, a single dose of the H9N2 ca vaccine administered intranasally was immunogenic in mice and conferred complete protection against replication of homologous and heterologous wild-type H9N2 influenza viruses in the upper and lower respiratory tract.[50] This vaccine virus has been evaluated in phase I clinical trials.[51]

An H7N3 candidate pLAIV that derived its HA and NA from the low pathogenicity avian influenza H7N3 isolate A/chicken/British Columbia/CN-6/2004 was generated by reverse genetics. As with the previous avian influenza/AA ca vaccine viruses, the H7N3 ca vaccine virus was extensively characterized in pre-clinical studies[52] and was shown to be safe for evaluation in phase I clinical trials (data on file). Candidate vaccines for the other HA subtypes are currently in development.


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