In this study, we used mice, chicken, and pigeons to compare the pathogenicity of 2 Thai highly pathogenic avian influenza viruses (HPAIVs) (Pigeon/Thailand/VSMU-7-NPT/2004 [Pigeon04] and Tree sparrow/Ratchaburi/VSMU-16-RBR/2005 [T.sparrow05]) isolated from wild birds. All chickens died 3 days after Pigeon04 infection, whereas 70% of them were killed by T.sparrow05 infection by day 4 post-infection and the rest survived until day 10 post-infection. Pigeon04 and T.sparrow05 caused 100% mortality in mice within 10 and 14 days post-infection, respectively. By contrast, 25% of pigeons died within 14 days of infection with 2 HPAIVs or medium only, suggesting that these viruses do not cause lethal infection in pigeons. These results clearly showed that the 2 HPAIVs exhibit different lethality in mice, chickens, and pigeons.
A comparison of host responses to Pigeon04 infection in mice and pigeons revealed that pigeons developed only mild pneumonia accompanied by low viral replications and poor inductions of cytokines such as interleukins 6 and 8 in the infected lungs. We therefore suggest that the outcomes of hosts against HPAIV infection likely depends on the severity of tissue injury associated with the magnitude of host cytokine expression induced by specific virus-host interactions.
(Viral Disease and Epidemiology Research Division)
References:
- Hayashi T. et al (2011) Virology 412:9-18
- Hayashi T. et al (2011) PLoS ONE 6:e23103
