tetano
Editor, Senior Moderator
Avian Pathol. 2015 May 29:1-33. [Epub ahead of print]
[h=1]Comparison of the effectiveness of rHVT-H5, inactivated H5 and rHVT-H5 with inactivated H5 prime/boost vaccination regimes in commercial broiler chickens carrying MDAs against HPAI H5N1 clade 2.2.1 virus challenge.[/h] Kilany WH[SUP]1[/SUP], Khalifa MK, Safwat M, Mohammed S, Selim A, VonDobschuetz S, Dauphin G, Lubroth J, Jobre Y.
[h=3]Author information[/h]
[h=3]Abstract[/h] Vaccination is the main tool implemented in Egypt since 2007 to control H5N1 avian influenza (AI). The present study aimed at comparing the effectiveness of three AI vaccination regimes in commercial broiler chickens carrying high levels of maternally-derived antibodies (MDAs). Day-old chicks (DOCs) were divided into four experimental groups. Group I received only the rHVT-H5 vaccine (recombinant Turkey herpes virus which carries a H5 clade 2.2 insert) administered at D1. Group II received only KV-H5 vaccine (inactivated reverse genetic H5N1 clade 2.3.4 virus) administered at D8. Group III received rHVT-H5 and KV-H5 as prime/boost. Group IV served as unvaccinated control. Weekly serological monitoring was conducted using the haemagglutination inhibition (HI) test. Two challenge experiments were conducted at D28 and D35 using HPAI H5N1 clade 2.2.1 virusBirds were monitored daily 14 days post-challenge (dpc) for morbidity and mortality and oropharyngeal swabs were collected for virological monitoring. Initially, DOCs had high mean MDA titers (9 ? 0.9 log[SUB]2[/SUB]). The MDA half-life was >7 and <7 days, respectively, for unvaccinated and vaccinated birds. Group III showed the highest post-vaccination humoral immune response and sero-conversion rate. The highest protection rate against morbidity (80-90%) and mortality (90-90%) was obtained in Group III after challenge at D28 and D35 respectively, as compared to Group I (70-70%) and (80-90%) and Group II (0-0%) and (30-30%). Groups I and III had lower number of shedder birds. The vaccination regime with prime/boost conferred the highest and earliest protection, and can hence be recommended for the broiler production sector in endemic and high HPAI H5N1 challenge areas Abbreviations: A/H5N1 = Avian influenza H5N1, Ct = Cut threshold, DOC = day-old chicken, dpc = days post challenge, ECE = embryonated chicken eggs, EID50 = embryo infective dose (50%), GOVS = General Organisation of Veterinary Services, HAU = Haemagglutination unit, HI = Haemagglutination inhibition, HPAI = highly pathogenic avian influenza, KV-H5 = an oil emulsion killed vaccine prepared from reassortant HPAI virus (A/duck/Anhui/1/06), PFU = plaque-forming unit, OIE = World Organisation for Animal Health, QRT-PCR = Quantitative Real time reverse transcription polymerase chain reaction, rHVT = recombinant herpes virus of turkey, RNA = ribonucleic acid.
PMID: 26023824 [PubMed - as supplied by publisher]
[h=1]Comparison of the effectiveness of rHVT-H5, inactivated H5 and rHVT-H5 with inactivated H5 prime/boost vaccination regimes in commercial broiler chickens carrying MDAs against HPAI H5N1 clade 2.2.1 virus challenge.[/h] Kilany WH[SUP]1[/SUP], Khalifa MK, Safwat M, Mohammed S, Selim A, VonDobschuetz S, Dauphin G, Lubroth J, Jobre Y.
[h=3]Author information[/h]
[h=3]Abstract[/h] Vaccination is the main tool implemented in Egypt since 2007 to control H5N1 avian influenza (AI). The present study aimed at comparing the effectiveness of three AI vaccination regimes in commercial broiler chickens carrying high levels of maternally-derived antibodies (MDAs). Day-old chicks (DOCs) were divided into four experimental groups. Group I received only the rHVT-H5 vaccine (recombinant Turkey herpes virus which carries a H5 clade 2.2 insert) administered at D1. Group II received only KV-H5 vaccine (inactivated reverse genetic H5N1 clade 2.3.4 virus) administered at D8. Group III received rHVT-H5 and KV-H5 as prime/boost. Group IV served as unvaccinated control. Weekly serological monitoring was conducted using the haemagglutination inhibition (HI) test. Two challenge experiments were conducted at D28 and D35 using HPAI H5N1 clade 2.2.1 virusBirds were monitored daily 14 days post-challenge (dpc) for morbidity and mortality and oropharyngeal swabs were collected for virological monitoring. Initially, DOCs had high mean MDA titers (9 ? 0.9 log[SUB]2[/SUB]). The MDA half-life was >7 and <7 days, respectively, for unvaccinated and vaccinated birds. Group III showed the highest post-vaccination humoral immune response and sero-conversion rate. The highest protection rate against morbidity (80-90%) and mortality (90-90%) was obtained in Group III after challenge at D28 and D35 respectively, as compared to Group I (70-70%) and (80-90%) and Group II (0-0%) and (30-30%). Groups I and III had lower number of shedder birds. The vaccination regime with prime/boost conferred the highest and earliest protection, and can hence be recommended for the broiler production sector in endemic and high HPAI H5N1 challenge areas Abbreviations: A/H5N1 = Avian influenza H5N1, Ct = Cut threshold, DOC = day-old chicken, dpc = days post challenge, ECE = embryonated chicken eggs, EID50 = embryo infective dose (50%), GOVS = General Organisation of Veterinary Services, HAU = Haemagglutination unit, HI = Haemagglutination inhibition, HPAI = highly pathogenic avian influenza, KV-H5 = an oil emulsion killed vaccine prepared from reassortant HPAI virus (A/duck/Anhui/1/06), PFU = plaque-forming unit, OIE = World Organisation for Animal Health, QRT-PCR = Quantitative Real time reverse transcription polymerase chain reaction, rHVT = recombinant herpes virus of turkey, RNA = ribonucleic acid.
PMID: 26023824 [PubMed - as supplied by publisher]