Pathogenicity of Genetically Similar, H5N1 Highly Pathogenic Avian Influenza Virus Strains in Chicken and the Differences in Sensitivity among Different Chicken Breeds

Abstract

Differences in the pathogenicity of genetically closely related H5N1 highly pathogenic avian influenza viruses (HPAIVs) were evaluated in White Leghorn chickens. These viruses varied in the clinical symptoms they induced, including lethality, virus shedding, and replication in host tissues. A comparison of the host responses in the lung, brain, and spleen suggested that the differences in viral replication efficiency were related to the host cytokine response at the early phase of infection, especially variations in the proinflammatory cytokine IL-6. Based on these findings, we inoculated the virus that showed the mildest pathogenicity among the five tested, A/pigeon/Thailand/VSMU-7-NPT/2004, into four breeds of Thai indigenous chicken, Phadu-Hung-Dang (PHD), Chee, Dang, and Luang-Hung-Khao (LHK), to explore effects of genetic background on host response. Among these breeds, Chee, Dang, and LHK showed significantly longer survival times than White Leghorns. Virus shedding from dead Thai indigenous chickens was significantly lower than that from White Leghorns. Although polymorphisms were observed in the Mx and MHC class I genes, there was no significant association between the polymorphisms in these loci and resistance to HPAIV.

Age is not a determinant factor in susceptibility of broilers to H5N2 clade 2.3.4.4 high pathogenicity avian influenza virus

“…Differences in susceptibility between layers and broilers have been reported for AI virus infection [24–31]. Experimentally, the intravenous inoculation of high dose of A/chicken/Alabama/7395/75 (H4N8) caused more severe renal disease in White Leghorns than in broilers [24].…”

Risk Factors for Avian Influenza H9 Infection of Chickens in Live Bird Retail Stalls of Lahore District, Pakistan 2009–2010

“…Hence, mixing of different breeds may increase the likelihood of dissemination and genetic reassortment of influenza viruses 3 due to variable pathogenicity of AIV in indigenous and commercial breeds 31 . Differences in the lethality of HPAIV infection among various lines or breeds of chicken have been described previously 32 .…”

Creating Disease Resistant Chickens: A Viable Solution to Avian Influenza?

“…Whilst this area of research still remains somewhat in its infancy, in outbreaks of HPAI viruses there are often a proportion of birds who survive the outbreak [ 6 , 37 ], suggesting that host-dependent differences can influence disease outcome. Similarly, certain breeds of chickens are known to be inherently less susceptible to IAV [ 38 , 39 , 40 ]. For example, there was a significant difference in viral shedding between two inbred lines of chicken infected with LPAI A/Turkey/England/647/77(H7N7) [ 38 ].…”

“…For example, there was a significant difference in viral shedding between two inbred lines of chicken infected with LPAI A/Turkey/England/647/77(H7N7) [ 38 ]. Similarly, Thai indigenous chickens shed significantly less HPAI H5N1 than White Leghorns [ 39 ] whilst Fayoumi chickens shed significantly less LPAI H5N2 than Leghorn chickens [ 40 ]. The genetic basis for this differential susceptibility remains incompletely understood, although it has been associated with host-dependent differences in innate immunity [ 38 ].…”