Serum virus neutralization assay for detection and quantitation of serum-neutralizing antibodies to influenza A virus in swine.

The serum virus neutralization (SVN) assay is a serological test to detect the presence and magnitude of functional systemic antibodies that prevent infectivity of a virus. The SVN assay is a highly sensitive and specific test that may be applied to influenza A viruses in swine to measure the titer of neutralizing antibodies post-infection or after vaccination. Conventional SVN methods performed in vitro are based on inhibition of virus infectivity in cell culture in the presence of neutralizing antibodies. Titer determination may be based on the presence or the absence of cytopathic effect or the evidence of viral infection using an immunoreactive technique. The SVN assay is relatively inexpensive using standard laboratory equipment although it requires cell culture, more time and labor, and technical skill to conduct the assay compared to other serological methods. The SVN test is useful to evaluate the level of serological cross-reactivity between vaccine antisera and variant influenza viruses that may correlate with cross-protection in the host.