tetano
Editor, Senior Moderator
J Virol. 2014 Aug 13. pii: JVI.02142-14. [Epub ahead of print]
The temperature sensitive and attenuation phenotypes conferred by mutations in the influenza PB2, PB1, and NP genes are influenced by the species of origin of the PB2 gene in reassortant viruses derived from influenza A/California/07/2009 and A/WSN/33.
Broadbent AJ1, Santos CP1, Godbout RA1, Subbarao K2.
Author information
Abstract
Live attenuated influenza vaccines in the US are derived from a human virus that is temperature sensitive (ts), characterized by restricted (≥ 100-fold) replication at 39?C. The ts genetic signature (ts sig) has been mapped to 5 loci in 3 genes: PB1 (391E, 581G, and 661T), PB2 (265S) and NP (34G). However, when transferred into avian and swine influenza viruses, only partial ts and attenuation phenotypes occur. To investigate the reason for this, we introduced the ts sig into the human-origin virus A/WSN/33 (WSN), the avian-origin virus A/Vietnam/1203/04 (VN04), and the swine-origin triple reassortant 2009 pandemic H1N1 virus A/California/07/2009 (CA07), which contains gene segments from human-, avian- and swine-viruses. The VN04 ts sig and CA07 ts sig viruses replicated efficiently in MDCK cells at 39?C, but the replication of WSN ts sig was restricted ≥ 100-fold compared to 33?C. Reassortant CA07 ts sig viruses were generated with individual polymerase gene segments from WSN, and vice versa. Only ts sig viruses with a PB2 gene segment derived from WSN were restricted in replication ≥ 100-fold at 39?C. In ferrets, the CA07 ts sig virus replicated in the upper and lower respiratory tracts, but the replication of a reassortant CA07 ts sig virus with a WSN PB2 gene was severely restricted in the lungs. Taken together, these data suggest that the origin of the PB2 gene segment influences the ts phenotype in vitro and attenuation in vivo. This could have implications for the design of novel live vaccines against animal-origin influenza viruses.
IMPORTANCE:
Live attenuated influenza vaccines (LAIV) on temperature sensitive (ts) backbones derived from animal-origin influenza viruses are being sought for use in the poultry and swine industries and to protect people against animal-origin influenza. However, inserting the ts genetic signature from a licensed LAIV backbone fails to fully attenuate these viruses. Our data indicate this is associated with the presence of a PB2 gene segment derived from an avian influenza virus. We show that a reassortant 2009 pandemic H1N1 virus with the ts signature from a licensed LAIV donor virus is ts in vitro and attenuated in vivo when the PB2 gene is derived from a human-origin virus but not from an avian virus. Our study provides information that could benefit the rational design of alternative LAIV backbones against animal-origin influenza viruses.
Copyright ? 2014, American Society for Microbiology. All Rights Reserved.
PMID:
25122786
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25122786
The temperature sensitive and attenuation phenotypes conferred by mutations in the influenza PB2, PB1, and NP genes are influenced by the species of origin of the PB2 gene in reassortant viruses derived from influenza A/California/07/2009 and A/WSN/33.
Broadbent AJ1, Santos CP1, Godbout RA1, Subbarao K2.
Author information
Abstract
Live attenuated influenza vaccines in the US are derived from a human virus that is temperature sensitive (ts), characterized by restricted (≥ 100-fold) replication at 39?C. The ts genetic signature (ts sig) has been mapped to 5 loci in 3 genes: PB1 (391E, 581G, and 661T), PB2 (265S) and NP (34G). However, when transferred into avian and swine influenza viruses, only partial ts and attenuation phenotypes occur. To investigate the reason for this, we introduced the ts sig into the human-origin virus A/WSN/33 (WSN), the avian-origin virus A/Vietnam/1203/04 (VN04), and the swine-origin triple reassortant 2009 pandemic H1N1 virus A/California/07/2009 (CA07), which contains gene segments from human-, avian- and swine-viruses. The VN04 ts sig and CA07 ts sig viruses replicated efficiently in MDCK cells at 39?C, but the replication of WSN ts sig was restricted ≥ 100-fold compared to 33?C. Reassortant CA07 ts sig viruses were generated with individual polymerase gene segments from WSN, and vice versa. Only ts sig viruses with a PB2 gene segment derived from WSN were restricted in replication ≥ 100-fold at 39?C. In ferrets, the CA07 ts sig virus replicated in the upper and lower respiratory tracts, but the replication of a reassortant CA07 ts sig virus with a WSN PB2 gene was severely restricted in the lungs. Taken together, these data suggest that the origin of the PB2 gene segment influences the ts phenotype in vitro and attenuation in vivo. This could have implications for the design of novel live vaccines against animal-origin influenza viruses.
IMPORTANCE:
Live attenuated influenza vaccines (LAIV) on temperature sensitive (ts) backbones derived from animal-origin influenza viruses are being sought for use in the poultry and swine industries and to protect people against animal-origin influenza. However, inserting the ts genetic signature from a licensed LAIV backbone fails to fully attenuate these viruses. Our data indicate this is associated with the presence of a PB2 gene segment derived from an avian influenza virus. We show that a reassortant 2009 pandemic H1N1 virus with the ts signature from a licensed LAIV donor virus is ts in vitro and attenuated in vivo when the PB2 gene is derived from a human-origin virus but not from an avian virus. Our study provides information that could benefit the rational design of alternative LAIV backbones against animal-origin influenza viruses.
Copyright ? 2014, American Society for Microbiology. All Rights Reserved.
PMID:
25122786
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25122786