Submitted to: American Journal of Veterinary Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2005
Publication Date: 11/1/2005
Citation: Wesley, R.D., Lager, K.M. 2005. Evaluation of a recombinant human adenovirus-5 vaccine administered via needle-free device and intramuscular injection for vaccination of pigs against swine influenza virus. American Journal of Veterinary Research. 66(11):1943-1947.
Interpretive Summary: Pathogens of the porcine respiratory disease complex (PRDC), including viral pathogens like swine influenza virus (SIV), cause pneumonia in pigs which is the industries' most costly disease. This research focuses on improved vectored vaccines for protection of weaned pigs against SIV and their effectiveness when administered by 2 different injection methods; traditional hypodermic needle injection vs. needle-free injection. Both methods stimulated a dose-dependent serological response in the vaccinated pigs. However, the response to traditional intramuscular vaccination was consistently better than the response to needle-free injection but the differences were statistically not significant. Moreover, traditional needle and syringe vaccination was superior at reducing nasal virus shedding except at the highest dose where both vaccine administration methods completely blocked virus replication. The severity of lung lesions was also reduced in a dose-dependent fashion by both vaccination methods. These improved second generation SIV vaccines will benefit swine producers and veterinarians.
Technical Abstract: Objective - to evaluate the level of protection in weaned pigs and safety of a human adenovirus 5 vaccine for SIV subtype H3N2 and its effectiveness when administered by 2 different injection methods. Animals - 76 conventional, outbred pigs from a specific pathogen free herd. Procedure - Six groups of 3-week-old pigs received a 10-fold serial dilution of the H3 expressing recombinant adenovirus vaccine either by a needle-free injection device or by traditional needle and syringe. Five weeks later the vaccinated pigs and non-vaccinated control pigs were challenged or sham-inoculated intratraecheally. In each group of 10 pigs, one pig was left as a non-vaccinated, contact pig for the entire 5 weeks to monitor possible pig to pig spread of the vaccine. Following challenge, pigs were observed for clinical signs, tested for nasal virus secretion and on day 5 post challenge lungs were observed for gross lesions and lung lavage fluids were tested for virus replication. Results - An HI antibody response occurred in vaccinated pigs in a dose dependent fashion. Traditional IM vaccination was consistently better than needle-free injection but the differences were statistically insignificant. Likewise, traditional needle and syringe vaccination was superior at reducing nasal virus shedding except at the highest dose where both vaccine administration methods completely blocked virus replication. The severity of lung lesions was also reduced in a dose dependent fashion by both vaccination methods. Conclusions and Clinical Relevance - The human adenovirus 5 vaccine at the high dose completely blocked nasal virus shedding post challenge, was safe and can be used in neonatal pigs that have interfering maternal antibodies.