Submitted to: Poultry Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/4/2009
Publication Date: 11/2/2009
Publication URL: hdl.handle.net/10113/37646
Citation: Layton, S.L., Kapczynski, D.R., Cox, M.M., Higgins, S., Higgins, J., Wolfenden, A.D., Liljebjelke, K.A., Bottje, W.G., Swayne, D.E., Berghman, L.R., Kwon, Y.M., Hargis, B.M., Cole, K. 2009. Vaccination of chickens with recombinant salmonella expressing the M2e and CD154 increase protection and decrease viral shedding following low pathogenic avian influenza challenge. Poultry Science. 88(11):2244-2252. Interpretive Summary: Avian influenza (AI) is viral diseases of poultry. Detection in commercial flocks can result in serious economic impact to the poultry industry. Vaccination against AI is used to increase protection of birds against disease and limit transmission to susceptible cohorts. Because of differences between individual AI viruses, no single vaccine protects against all AI viruses. The objectives of the present research were to extend the knowledge of vaccine induced protection by developing an AI vaccine with the potential to cross react with all AI viruses. The results clearly show that the vaccine developed here could increase protection and decrease transmission against low virulent AI. However, highly virulent AI still resulted in disease following challenge. These results are an important step in further development of vaccines for poultry against AI.
Technical Abstract: Avian influenza (AI) is a significant public health concern and serious economic threat to the commercial poultry industry worldwide. Previous research demonstrates that antibodies against M2e confer protection against influenza challenge. Using the Red recombinase system in combination with overlapping extension PCR, we recently developed several novel attenuated Salmonella enteritidis strains that express a protective M2e epitope in combination with a potential immune-enhancing CD154 peptide sequence on the Salmonella outer membrane protein lamB. Commercial Leghorn chicks were orally immunized (immunization dose: 106-108 cfu/chick) with saline (Negative Control) or one of the recombinant Salmonella strains (delta-aroA M2e-CD154, delta-htrA M2e-CD154, delta-aroA/delta-htrA M2e(4)-CD154) on day-of-hatch and 21 days post-hatch. These candidate vaccine strains were evaluated for their ability to invade, colonize, and persist in tissues and elicit an M2e-specific antibody response. The vaccine candidate strain delta-aroA M2e-CD154 exhibited significantly greater organ invasion in the liver and spleen at d 7 (p>0.05); however, no marked differences in colonization of the cecal tonsils was observed. Vaccinated chickens exhibited significantly increased M2e-specific IgG responses, which were further enhanced by simultaneous expression of CD154 (p<0.05). Virus neutralization assays gave neutralizing indices of 6.6, 6.3 and 6.3 for delta-aroA M2e-CD154, delta-htrA M2e-CD154, and delta-aroA/delta-htrA M2e(4)-CD154 7 days post-booster immunization, respectively, indicating effective neutralization of AI by serum IgG of vaccinated chickens. In a subsequent direct challenge study, SPF Leghorn chicks immunized with delta-aroA/delta-htrA M2e(4)-CD154 offered significant protection against direct challenge with low pathogenic AI (LPAI) H7N2, but not highly pathogenic H5N1 AI. Taken together, these date suggest that these Salmonella-vectored vaccines expressing M2e in association with CD154 are effective against at protecting chickens against LPAI.