tetano
Editor, Senior Moderator
Avian Pathol. 2014 Sep 23:1-38. [Epub ahead of print]
Protection conferred by recombinant HVT avian influenza (rHVT-H5) vaccine in rearing period in two commercial layer chicken breeds in Egypt.
Kilany W1, Dauphin G, Selim A, Tripodi A, Samy M, Sobhy H, VonDobschuetz S, Safwat M, Saad M, Erfan A, Hassan M, Lubroth J, Jobre Y.
Author information
Abstract
The effectiveness of recombinant turkey herpes virus with avian influenza (A/swan/Hungary/4999/2006(H5N1)) clade 2.2 virus (rHVT-H5) vaccine was evaluated in two layer chicken breeds (WB and BS). One dose of rHVT-H5 vaccine was administered at day 1 and birds serologically (HI test) and virologically monitored for 19 weeks. Maternally-derived antibody (MDA) and post-vaccination H5 antibody titers were measured using the Chinese (A/Goose/Guangdong/1/96(H5N1)) and the Egyptian (A/chicken/Egypt/128s/2012(H5N1)) HAs as antigens. The challenge was conducted at 19 weeks of age and on six experimental groups (I(WB) and II(BS), both vaccinated and challenged); (III(WB) and IV(BS), both vaccinated but not challenged); (V and VI, are unvaccinated SPF chickens, serving respectively as positive and negative controls). The challenge virus was the clade 2.2.1 HPAI H5N1 A/chicken/Egypt/128s/2012 at the dose of 106EID50. For both breeds, complete MDA waning occurred at the age of 4 weeks. The immune response to rHVT-H5 vaccination was detected from the 6th week. The seroconversion rates for both breeds reached 85.7%-100% on the 8th week of age. Protection levels of 73.3%, 60% and 0% were respectively recorded in Groups I, II and V. No mortalities occurred in the unchallenged groups. Group I showed superior results for all measured post-challenge parameters. As conclusion, a single rHVT-H5 hatchery vaccination conferred a high level of protection for a relatively extended period. This vaccine could be an important tool for future A/H5N1 prevention/control in endemic countries. Further studies on persistence of immunity beyond 19 weeks, need for booster with inactivated vaccines, breed susceptibility and vaccinal response, and transmissibility are recommended.
PMID:
25245772
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25245772
Protection conferred by recombinant HVT avian influenza (rHVT-H5) vaccine in rearing period in two commercial layer chicken breeds in Egypt.
Kilany W1, Dauphin G, Selim A, Tripodi A, Samy M, Sobhy H, VonDobschuetz S, Safwat M, Saad M, Erfan A, Hassan M, Lubroth J, Jobre Y.
Author information
Abstract
The effectiveness of recombinant turkey herpes virus with avian influenza (A/swan/Hungary/4999/2006(H5N1)) clade 2.2 virus (rHVT-H5) vaccine was evaluated in two layer chicken breeds (WB and BS). One dose of rHVT-H5 vaccine was administered at day 1 and birds serologically (HI test) and virologically monitored for 19 weeks. Maternally-derived antibody (MDA) and post-vaccination H5 antibody titers were measured using the Chinese (A/Goose/Guangdong/1/96(H5N1)) and the Egyptian (A/chicken/Egypt/128s/2012(H5N1)) HAs as antigens. The challenge was conducted at 19 weeks of age and on six experimental groups (I(WB) and II(BS), both vaccinated and challenged); (III(WB) and IV(BS), both vaccinated but not challenged); (V and VI, are unvaccinated SPF chickens, serving respectively as positive and negative controls). The challenge virus was the clade 2.2.1 HPAI H5N1 A/chicken/Egypt/128s/2012 at the dose of 106EID50. For both breeds, complete MDA waning occurred at the age of 4 weeks. The immune response to rHVT-H5 vaccination was detected from the 6th week. The seroconversion rates for both breeds reached 85.7%-100% on the 8th week of age. Protection levels of 73.3%, 60% and 0% were respectively recorded in Groups I, II and V. No mortalities occurred in the unchallenged groups. Group I showed superior results for all measured post-challenge parameters. As conclusion, a single rHVT-H5 hatchery vaccination conferred a high level of protection for a relatively extended period. This vaccine could be an important tool for future A/H5N1 prevention/control in endemic countries. Further studies on persistence of immunity beyond 19 weeks, need for booster with inactivated vaccines, breed susceptibility and vaccinal response, and transmissibility are recommended.
PMID:
25245772
[PubMed - as supplied by publisher]
http://www.ncbi.nlm.nih.gov/pubmed/25245772