Pathogenicity and transmissibility of the H5N1 subtype of highly pathogenic avian influenza (HPAI) isolated from domestic fowl and wild Mandarin ducks in 2010-2011 were examined in order to understand the changes in the viral characteristics associated with viral circulation among wild birds. The three viruses used in this study, A/chicken/Shimane/1/2010 (Ck10), A/chicken/Miyazaki/S4/2011 (CkS411), and A/mandarin duck/Miyazaki/22M-765/2011 (MD11), share the same genetic origin. Domestic fowl were intranasally inoculated with the three viruses, and all died. However, the survival period of domestic fowl inoculated with MD11 was longer than with CkS411. The viral load in the tracheae and cloacae of domestic fowl infected with MD11 was significantly lower than in those infected with either Ck10 or CkS411. Naive birds that cohabited with a bird infected with each of the three viruses, died through viral transmission. The period that all birds in a group survived during the transmission test was much longer in the MD11 group than in any of the other groups. The lower viral multiplication of MD11 in domestic fowl may affect the survivability and transmissibility of this virus. As the viral spread time among domestic fowls became longer, detection of HPAI in domestic fowl would delay when the HPAIvirus circulating among wild birds in the field is introduced into domestic fowl.
(Viral Disease and Epidemiology Research Division)
References:
Uchida Y. et al. (2012) Virus Research 170(1-2):109-117
