tailieunhanh - Báo cáo y học: " Improved hatchability and efficient protection after in ovo vaccination with live-attenuated H7N2 and H9N2 avian influenza viruses"

Tuyển tập báo cáo các nghiên cứu khoa học quốc tế ngành y học dành cho các bạn tham khảo đề tài: Improved hatchability and efficient protection after in ovo vaccination with live-attenuated H7N2 and H9N2 avian influenza viruses | Cai et al. Virology Journal 2011 8 31 http content 8 1 31 J VIROLOGY JOURNAL RESEARCH Open Access Improved hatchability and efficient protection after in ovo vaccination with live-attenuated H7N2 and H9N2 avian influenza viruses i z- 3 T- s r- . Yibin Cai Haichen Song Jianqiang Ye Hongxia Shao Rangarajan Padmanabhan Troy C Sutton Daniel R Perez1 2 Abstract Mass in ovo vaccination with live attenuated viruses is widely used in the poultry industry to protect against various infectious diseases. The worldwide outbreaks of low pathogenic and highly pathogenic avian influenza highlight the pressing need for the development of similar mass vaccination strategies against avian influenza viruses. We have previously shown that a genetically modified live attenuated avian influenza virus LAIV was amenable for in ovo vaccination and provided optimal protection against H5 HPAI viruses. However in ovo vaccination against other subtypes resulted in poor hatchability and therefore seemed impractical. In this study we modified the H7 and H9 hemagglutinin HA proteins by substituting the amino acids at the cleavage site for those found in the H6 HA subtype. We found that with this modification a single dose in ovo vaccination of 18day old eggs provided complete protection against homologous challenge with low pathogenic virus in 70 of chickens at 2 or 6 weeks post-hatching. Further inoculation of 19-day old egg embryos with 106 EID50 of LAIVs improved hatchability to 90 equivalent to unvaccinated controls with similar levels of protection. Our findings indicate that the strategy of modifying the HA cleavage site combined with the LAIV backbone could be used for in ovo vaccination against avian influenza. Importantly with protection conferred as early as 2 weeks post-hatching with this strategy birds would be protected prior to or at the time of delivery to a farm or commercial operation. Introduction Although depopulation of infected flocks