VSV-vectored H1/N1 vaccine prevented shedding of drifted influenza virus in pigs
A non-propagating VSV vector encoding H1/N1 antigens prevented detectable shedding of a drifted influenza challenge virus in pigs. The vaccine also induced cross-reactive immunity and inhibited avian N1 activity.
A non-propagating vesicular stomatitis virus (VSV) vector encoding HA and NA antigens of A/Hamburg/4/2009 (H1N1) prevented detectable virus shedding in vaccinated pigs after nasal challenge with a 6:2 reassortant virus encoding drifted HA and NA antigens. A single intramuscular immunization elicited high titers of H1N1-neutralizing antibodies and potent N1-sialidase inhibition, and a boost enhanced inhibitory activity against the antigen-drifted A/Victoria/2570/2019 (H1N1) strain.
The study evaluated the vaccine in a porcine animal model to assess induction of cross-reactive immunity. A boost with the same single-cycle VSV-vectored H1/N1 antigens or with a live-attenuated influenza vaccine enhanced inhibitory activity against the drifted H1N1 strain.
Vaccination induced N1-specific antibodies that also inhibited avian N1 sialidase and suppressed replication of a bovine-derived H5N1 virus in vitro. Following challenge, vaccinated pigs showed no detectable virus shedding, whereas control animals shed infectious virus.
Homologous prime-boost vaccination with the VSV-vectored H1/N1 antigens conferred protection comparable to the heterologous VSV/LAIV regimen in the upper respiratory tract. The findings showed that a single-cycle VSV vector encoding both HA and NA induces cross-protective immunity against antigen-drifted influenza viruses and may limit infection by zoonotic H5N1 viruses.