Attenuation and immunogenicity in mice of temperature-sensitive influenza viruses expressing truncated NS1 proteins Falcón, Ana M. and Fernandez-Sesma, Ana and Nakaya, Yurie and Moran, Thomas M. and Ortín, Juan and García-Sastre, Adolfo,, 86, 2817-2821 (2005), doi = https://doi.org/10.1099/vir.0.80991-0, publicationName = Microbiology Society, issn = 0022-1317, abstract= It was previously shown that two mutant influenza A viruses expressing C-terminally truncated forms of the NS1 protein (NS1-81 and NS1-110) were temperature sensitive in vitro. These viruses contain HA, NA and M genes derived from influenza A/WSN/33 H1N1 virus (mouse-adapted), and the remaining five genes from human influenza A/Victoria/3/75 virus. Mice intranasally infected with the NS1 mutant viruses showed undetectable levels of virus in lungs at day 3, whereas those infected with the NS1 wild-type control virus still had detectable levels of virus at this time. Nevertheless, the temperature-sensitive mutant viruses induced specific cellular and humoral immune responses similar to those induced by the wild-type virus. Mice immunized with the NS1 mutant viruses were protected against a lethal challenge with influenza A/WSN/33 virus. These results indicate that truncations in the NS1 protein resulting in temperature-sensitive phenotypes in vitro correlate with attenuation in vivo without compromising viral immunogenicity, an ideal characteristic for live attenuated viral vaccines., language=, type=