To identify critical phenotypes that affect avian influenza virus transmission in chickens, we compared the transmissibility of three H5N1 highly pathogenic viruses of different pathogenicity in chickens by monitoring the exact time of death by using wireless thermosensors. This study showed that, despite quick deaths, the most virulent H5N1 A/chicken/Yamaguchi/7/2004 was transmitted quickly in chickens via contact and airborne routes. Intermediate virulent H5N1 A/chicken/Miyazaki/K11/2007 spread moderately, and less virulent H5N1 A/duck/Yokohama/aq10/2003, which causes severe clinical signs and a long period to death, spread slowly among the animals. The transmissibility was correlated with virus titers of oropharyngeal and cloacal swabs, and the time for swab virus titers to reach 50% chicken infective dose affected the transmission speed. These results demonstrate that the peak virus titers excreted and the time required for virus titers to reach a minimal chicken infectious dose may be the critical phenotypes influencing the transmissibility of highly pathogenic avian influenza viruses in chickens.
(Research Team for Zoonotic Diseases)
Suzuki K. et al. (2010) J. Gen. Virol. 91: 2302-2306