Influenza viruses (IFV) are segmented RNA viruses that cause seasonal influenza epidemics and influenza pandemics. IFV A can infect and transmit between birds and some mammals (e.g. pigs and humans) while IFV B only infects humans and seals. Both influenzaviruses pose a severe threat to public health and the agricultural economy. The viruses mutate quickly by both antigenic drift and reassortment requiring the development and reformulation of new vaccines each year. Viruses resistant to almost all known drugs have been identified, making drug development a critical pursuit. Concerns about IFV have been further heightened due to the potential for transmission of highly pathogenic avian influenza (HPAI) strains to humans.
IBT Bioservices has developed several mouse models of IFV infection wherein mice are inoculated intranasally with an LD90 dose of virus. Test articles are administered per client instruction, and positive controls are available for comparison. Routine study endpoints include:
IBT's challenge virus seeds are well characterized and lead to highly reproducible lethality rates. To demonstrate this characterization, a meta-analysis was performed on over 30 groups challenged with an LD90 of the IFV A/Texas/36/91 (H1N1) strain (~52 PFU). The result was an average 12.4% survival rate (very near the theoretical 10%) with a mean time to death of 8.2 days.
It is often of interest to test candidate anti-IFV therapies against flu strains which are resistant to the standard of care, Tamiflu. IBT Bioservices offers a mouse model of IFV A/Perth/261/2009, which has the naturally occuring H275Y Tamiflu resistance mutation.
IBT Bioservices is well equipped to perform IFV vaccine efficacy and immunogenicity studies, with several ancillary assays established for supporting data.