#11-038

Complete

Date Full Report Received

08/31/2012

Date Abstract Report Received

08/31/2012

Investigation

Institution:
Primary Investigator:

The 2009 influenza pandemic and the recent H3N2v events have highlighted the constant threat that influenza viruses represent for people and animals. Because influenza viruses are shared between humans, avian and mammals, understanding interspecies transmission and the risk for influenza spread is a priority.
Influenza can be transmitted through direct contact and indirectly through aerosols and contaminated fomites. In this study we evaluated the effect of vaccination in aerosol shedding in experimentally infected pigs. Three groups of pigs were vaccinated with various vaccines representative of strategies used in commercial pig production. Two vaccines were selected to confer partial immunity against the challenge strain, while one vaccine was selected to be autogenous to the challenge virus. Additionally one group was left un-vaccinated and served as control. Environmental temperature and relative humidity readings were taken throughout the study. Pigs were challenged with an influenza A virus strain two weeks after the second vaccination and tested daily throughout the study. Air samples were also taken daily three times a day using a high volume air sampler. All samples were evaluated by RT-PCR and compared between the groups. Average temperature and relative humidity throughout the study was 27C (80F) and 53%, respectively. Results indicated that vaccinated groups had lower levels of virus shedding in nasal secretions compared to non-vaccinated pigs and influenza virus was not detected in the air of any of the vaccinated groups. In contrast, positive air samples were detected in the non-vaccinated group at 1, 2 and 3 days post infection. Overall the level of influenza detection in air samples was low most likely due to the elevated environmental temperature. In conclusion, influenza virus was detected in air samples from non-vaccinated pigs, and not in vaccinated animals, suggesting that vaccine may have an effect not only in decreasing the levels of nasal shedding but also in decreasing the risk of aerosol transmission by reducing the amount of virus shed in the air. This study offers a new perspective to the use of vaccination to potentially decrease the risk of influenza virus interspecies transmission and influenza virus regional dissemination.
Montserrat Torremorell (torr0033@umn.edu).