title: Influenza virus inactivation for studies of antigenicity and phenotypic neuraminidase inhibitor resistance profiling.
abstract: Introduction of a new influenza virus in humans urges quick analysis of its virological and immunological characteristics to determine the impact on public health and to develop protective measures for the human population. At present, however, the necessity of executing pandemic influenza virus research under biosafety level 3 (BSL-3) high-containment conditions severely hampers timely characterization of such viruses. We tested heat, formalin, Triton X-100, and beta-propiolactone treatments for their potencies in inactivating human influenza A(H3N2) and avian A(H7N3) viruses, as well as seasonal and pandemic A(H1N1) virus isolates, while allowing the specimens to retain their virological and immunological properties. Successful heat inactivation coincided with the loss of hemagglutinin (HA) and neuraminidase (NA) characteristics, and beta-propiolactone inactivation reduced the hemagglutination titer and NA activity of the human influenza virus 10-fold or more. Although Triton X-100 treatment resulted in inconsistent HA activity, the NA activities in culture supernatants were enhanced consistently. Nonetheless, formalin treatment permitted the best retention of HA and NA properties. Triton X-100 treatment proved to be the easiest-to-use influenza virus inactivation protocol for application in combination with phenotypic NA inhibitor susceptibility assays, while formalin treatment preserved B-cell and T-cell epitope antigenicity, allowing the detection of both humoral and cellular immune responses. In conclusion, we demonstrated successful influenza virus characterization using formalin- and Triton X-100-inactivated virus samples. Application of these inactivation protocols limits work under BSL-3 conditions to virus culture, thus enabling more timely determination of public health impact and development of protective measures when a new influenza virus, e.g., pandemic A(H1N1)v virus, is introduced in humans.
authors.affiliation: National Institute for Public Health and the Environment, Center for Infectious Disease Control, Laboratory for Infectious Diseases and Screening, Bilthoven, Netherlands. marcel.jonges@rivm.nl
authors.forename: Marcel
authors.initials: M
authors.lastname: Jonges
authors.forename: Wai Ming
authors.initials: WM
authors.lastname: Liu
authors.forename: Erhard
authors.initials: E
authors.lastname: van der Vries
authors.forename: Ronald
authors.initials: R
authors.lastname: Jacobi
authors.forename: Inge
authors.initials: I
authors.lastname: Pronk
authors.forename: Claire
authors.initials: C
authors.lastname: Boog
authors.forename: Marion
authors.initials: M
authors.lastname: Koopmans
authors.forename: Adam
authors.initials: A
authors.lastname: Meijer
authors.forename: Ernst
authors.initials: E
authors.lastname: Soethout
mesh_terms: D000998:Antiviral Agents / Q000494:pharmacology; D003264:Containment of Biohazards / Q000379:methods*; D004203:Disinfection / Q000379:methods*; D005260:Female; D006801:Humans; D009980:Influenza A virus / Q000187:drug effects / Q000502:physiology* / Q000528:radiation effects; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D050296:Microbial Viability; D008875:Middle Aged; D009439:Neuraminidase / Q000037:antagonists & inhibitors; D016273:Occupational Exposure / Q000517:prevention & control*; D009975:Orthomyxoviridae / Q000187:drug effects / Q000276:immunology; D038301:Virus Inactivation
chemical_list: D000998:Antiviral Agents; D009439:Neuraminidase