Location: Virus and Prion Research2012 Annual Report
1a. Objectives (from AD-416):
1. Identify swine influenza virus strain specific antigenic epitopes to support the development of serological assays for surveillance in swine. 2. Compare pathogenesis and transmissibility of selected isolates of the wild-type novel A/HINI virus from animals (e.g., Canadian, Chilean and Argentinean viruses) and correlate with genetic and antigenic changes. 3. Determine efficacy of conventional inactivated swine influenza vaccines against emerging isolates of pandemic A/H1Nl from animals (e.g., Canadian, Chilean and Argentinean viruses). 4. Evaluate a reverse genetics-derived modified live vaccine in pigs and other susceptible animal hosts against pandemic A/H1N1. 5. Evaluate an adenovirus-vectored influenza virus vaccine in pigs.
1b. Approach (from AD-416):
1. Conduct immunological investigations of influenza A virus components that lead to immune responses against specific epitopes that may enable serological surveillance for the 2009 A/H1N1 in swine and determine whether heterologous immunity against endemic swine influenza viruses interferes with serological surveillance methods. 2. Conduct an animal study to determine the pathogenesis and transmissibility of selected isolates of the wild-type novel A/HINI virus from animals and correlate with genetic and antigenic changes. 3. Conduct an animal study to determine the efficacy of conventional inactivated swine influenza vaccines against emerging isolates of pandemic A/H1Nl from animals. 4. Conduct an animal study utilizing a reverse genetics-derived modified live vaccine in pigs and other susceptible animal hosts against pandemic A/H1N1. 5. Conduct an animal study evaluating an adenovirus-vectored H1N1 influenza virus vaccine in pigs.
3. Progress Report:
We compared the immunogenicity and efficacy of a single intranasal dose of an human adenovirus 5 (Ad5)-vectored hemagglutinin (HA) vaccine to traditional intramuscular (IM) administration of whole inactivated virus vaccine (WIV). The Ad5-HA vaccine provided protective immunity to homologous challenge and partial protection against heterologous challenge, unlike the WIV vaccine. While the Ad5-HA vaccine did not prevent development of lung lesions following heterologous challenge, nasal viral shedding was significantly reduced and virus was cleared from the lung by 5 days post infection. Furthermore, the Ad5-HA vaccine induced a mucosal IgA response towards homologous virus and primed an antigen-specific IFNgamma response against both challenge viruses. The WIV vaccinated pigs displayed vaccine associated enhanced respiratory disease (VAERD) following heterologous challenge, characterized by enhanced macroscopic lung lesions 5 days following challenge. This study demonstrates that a single intranasal vaccination with an Ad5 construct encoding the HA of influenza can provide complete protection to homologous challenge and partial protection to heterologous challenge, as opposed to VAERD, which can occur with adjuvanted WIV vaccine. We then utilized an adenovirus (Ad5) vector vaccine platform that expressed IAV hemagglutinin (HA) or nucleoprotein (NP) to determine if the Ad5-vectored vaccine platform would result in vaccine associated enhanced respiratory disease (VAERD) as has been seen with WIV vaccine. Weaned commercial pigs received 2 doses three weeks apart of either IM Ad5-HA, IM Ad5-NP, IM Ad5-HA + NP (2 groups), IM whole inactivated virus (WIV) vaccine (VAERD positive control group), IM Ad5-empty vector or intranasal (IN) Ad5-HA + NP. Three weeks post boost vaccination six groups of pigs were challenged with heterologous 10**6 TCID50 /mL H1N1pdm09 (A/California/04/09 (CA/09)). The VAERD control group had the most severe lesions. Histopathology lesions followed a similar pattern and were most severe in the WIV VAERD control group. The Ad5 vectored HA, whether given IN or given IM alone or in combination with Ad5-NP protected against lung lesions and did not contribute to VAERD. In conclusion, pigs vaccinated with Ad5 vaccines had significantly reduced lung lesions as compared to the VAERD pigs. These results illustrate replication deficient Ad5-vectored vaccines with either IAV HA or NP proteins were not associated with VAERD.
Kappes, M.A., Sandbulte, M.R., Platt, R., Wang, C., Lager, K.M., Henningson, J.N., Lorusso, A., Vincent, A.L., Loving, C.L., Roth, J.A., Kehrli Jr, M.E. 2012. Vaccination with NS1-truncated H3N2 swine influenza virus primes T cells and confers cross-protection against an H1N1 heterosubtypic challenge in pigs. Vaccine. 30(2):280-288.