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United States Department of Agriculture

Agricultural Research Service

Research Project: SWINE VIRAL DISEASES PATHOGENESIS AND IMMUNOLOGY Title: Efficacy of Inactivated Swine Influenza Virus Vaccines Against the 2009 A/H1N1 Influenza Virus in Pigs

Authors
item VINCENT, AMY
item Ciacci-Zanella, Janice -
item Lorusso, Alessio
item Gauger, Philip -
item Zanella, Eraldo -
item Kehrli Jr, Marcus
item Janke, Bruce -
item LAGER, KELLY

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 20, 2010
Publication Date: March 24, 2010
Citation: Vincent, A.L., Ciacci-Zanella, J.R., Lorusso, A., Gauger, P.C., Zanella, E.L., Kehrli Jr, M.E., Janke, B.H., Lager, K.M. 2010. Efficacy of Inactivated Swine Influenza Virus Vaccines Against the 2009 A/H1N1 Influenza Virus in Pigs. Vaccine 28(15):2782-2787.

Interpretive Summary: The human pandemic H1N1 2009 virus has been shown to infect pigs. However, because of differences between the pandemic H1N1 2009 virus and influenza viruses that normally infect pigs, it was not known if vaccines currently used in the U.S. swine industry would protect pigs from H1N1 2009. The objective of this study was to evaluate if vaccines available in the U.S. as well as an experimental homologous A/H1N1 2009 vaccine could prevent infection and disease from 2009 pandemic A/H1N1. All of the vaccines tested provided partial protection ranging from reduction of pneumonia lesions to significant reduction in virus levels in the lung and nose. The current swine influenza vaccines demonstrated partial protection; however, none were able to prevent all nasal shedding or clinical disease such as fevers. An experimental homologous 2009 A/H1N1 monovalent vaccine provided the best protection overall, with no virus detected from nose or lung at any time point in addition to elimination of clinical disease. Based on the results with the vaccines evaluated in this study, the U.S. swine herd likely has significant protection against the 2009 A/H1N1 from prior vaccination or infection with swine influenza virus. However, consideration should be given for development of monovalent homologous vaccines to best protect the swine population. This will increase the well-being of swine, prevent financial loss to producers, and reduce the risk of pigs playing a role in the cycle of transmission of 2009 A/H1N1 in people.

Technical Abstract: The gene constellation of the 2009 pandemic A/H1N1 virus is a unique combination from swine influenza A viruses (SIV) of North American and Eurasian lineages, but prior to April 2009 had never before been identified in swine or other species. Although its hemagglutinin gene is related to North American H1 SIV, it is unknown if vaccines currently used in U.S. swine would cross-protect against infection with the pandemic A/H1N1. The objective of this study was to evaluate the efficacy of inactivated vaccines prepared with North American swine influenza viruses as well as an experimental homologous A/H1N1 vaccine to prevent infection and disease from 2009 pandemic A/H1N1. All vaccines tested provided partial protection ranging from reduction of pneumonia lesions to significant reduction in virus replication in the lung and nose. The multivalent vaccines demonstrated partial protection; however, none were able to prevent all nasal shedding or clinical disease. An experimental homologous 2009 A/H1N1 monovalent vaccine provided optimal protection with no virus detected from nose or lung at any time point in addition to amelioration of clinical disease. Based on cross-protection demonstrated with the vaccines evaluated in this study, the U.S. swine herd likely has significant immunity to the 2009 A/H1N1 from prior vaccination or natural exposure. However, consideration should be given for development of monovalent homologous vaccines to best protect the swine population thus limiting shedding and the potential transmission of 2009 A/H1N1 from pigs to people.

Last Modified: 9/10/2014
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