Sendai virus intra-host population dynamics and host immunocompetence influence viral virulence during in vivo passage

Peña, José; Chen-Harris, Haiyin; Allen, Jonathan E.; Hwang, Mona; Elsheikh, Maher; Mabery, Shalini; Bielefeldt-Ohmann, Helle; Zemla, Adam T.; Bowen, Richard A.; Borucki, Monica K.

Lung tissues were collected on day 7 and histopathology scores were determined as a measure of virulence in the lungs of mice infected with SeV passage 1 (P1), P4, P7, and P10. Within diet groups, only mice receiving a ND were shown to have a statistically significant increase in histopathology scores, while histopathology scores of mice under FD and SD diet conditions trended up ( Fig. 2A) . Analysis of histopathology scores between diet groups demonstrated a statistically significant increase between P1 of SD mice compared with P1 of FD mice. The increase in histopathology scores was not associated with increased in viral loads following serial passage. The viral titer in BAL for each diet group averaged $1.6 Â 10 5 PFU/ml and there were no significant difference between groups. However, viral titers within diet groups trended lower with passage and there was a statistically significant decrease in SeV titers between P1 and P10 in SD mice (Fig. 2B) .