Pathological characteristics of coxsackievirus A14 in neonatal mice model

Fig. 1. Establishment of the CVA14 infection model. The body weights (A, D and G), clinical scores (B, E and H), and survival rates (C, F and I) in each group of neonatal mice (n = 7) were monitored and recorded daily until 10 dpi for exploring optimal challenge dose, challenge route and mouse age. Clinical symptoms of CVA14 infection in 2-day-old mice at 5 and 7 dpi, respectively (J and K). * and ** represent that the experimental subjects in the negative control group were 2-day-old and 6-day-old mice, respectively

Fig. 2. Change of virus titer in multiple tissues. 2-day-old ICR neonatal mice were inoculated with a lethal dose of CVA14 strain HE27. At 1–8 dpi, virus titers in the brain (A), lung (B), heart (C), liver (D), spleen (E), intestine (F) and muscle (G) represent the average data from six samples. Experimental group vs. negative control group, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, n.s. indicates not significant

Fig. 3. Histopathological examination (200×) for 2-day-old neonatal mice were i.m. inoculated with HE27 strain. Tissue samples from the brain (A−2), lung (B−2), heart (C−2), liver (D−2), spleen (E−2), intestine (F−2) and hindlimb muscle (G−2) were analyzed for pathology at 2 dpi, In addition, pathological results of tissues at 4 (A−3, B−3, C−3, D−3, E−3, F−3 and G−3), 6 (A−4, B−4, C−4, D−4, E−4, F−4 and G−4) and 8 dpi (A−5, B−5, C−5, D−5, E−5, F−5 and G−5) were obtained. Negative control groups were treated with the culture medium without observing no obvious histological changes in each tissue (A−1, B−1, C−1, D−1, E−1, F−1 and G−1)

Fig. 4. Immunohistochemical examination (200×) for 2-day-old neonatal mice were i.m. inoculated with HE27 strain. Tissue samples from the brain (A−2), lung (B−2), heart (C−2), liver (D−2), spleen (E−2), intestine (F−2) and hindlimb muscle (G−2) were analyzed for distribution of viral antigens at 2 dpi, In addition, Immunohistochemical results of tissues at 4 (A−3, B−3, C−3, D−3, E−3, F−3 and G−3) and 8 dpi (A−4, B−4, C−4, D−4, E−4, F−4 and G−4) were obtained. Negative control groups were treated with the culture medium without observing no obvious distribution of viral antigens in each tissue (A−1, B−1, C−1, D−1, E−1, F−1 and G−1)

Fig. 5. Cytokine expression level in the CVA14 infection. After the 2-day-old neonatal mice were challenged with a lethal dose of HE27 strain, the expression levels of IL−4 (A), IL−10 (B), IFN-γ (C) and TNF-α (D) were detected by ELISA at 1–8 dpi (n = 6). The difference analysis was conducted by two-tailed Student’s t-test or Mann-Whiteny test. Experimental group vs. negative control group, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, n.s. indicates not significant