H5N6 Has Become Highly Virulent in Mice
To understand the pathogenicity of the different epidemic H5N6 of avian influenza to mice, we selected three H5N6 strains (A/duck/jiangsu/18012/2018, A/duck/guangdong/18217/2018, A/chicken/guangdong/18231/2018) and one H5N1 strain (A/duck/shandong/17771/2017) as control, hereinafter referred to as 18012,18217,18231,17771 respectively) to infect in mice and detect the EID50 in the different organs.
Three strains of H5N6 showed different virulence in mice.18012 had the strongest virulence among the four strains as 50% of the mice died within three days of challenge, and all of the mice died in four days of challenge [Figure 5 A, B]. 18012 maintained a high virus concentration in the lungs and brain in the 3-5 dpi period. The strain 17771 was slightly less virulent than 18012,all of the mice died in 5 days of post-challenge.18217 showed a moderate virulence in mice, which caused partial death at the 7 dpi, 30% survived in 14 dpi. 18231 showed a weak virulence in mice, as 100% were alive 14 dpi [Figure 5A, B] and only showed decreased body weight. Four strains had detected different viral levels in different organs. And the concentration was highest in the lungs. Strains 17772 and 18012 were detected in the brain at 3 dpi, whereas strains 17772, 18012, and 18217 were detected in the brain at 5 dpi [Figure 5C, D]. This suggests that 17772, 18012, and 18217 can cross the blood−brain barrier.