These in turn serve as templates fro RNA replication. Newly synthesised minus strands associate with N protein and transcriptase to produce nucleocapsids, which eventually associate with M protein at the apical surface of the membrane into which HN or F proteins have migrated, casuing cells to fuse with adjacent uninfected cells. Infection occurs via the respiratory tract. Transported by macrophages to lymph nodes. About six days after infection viremia occurs.
Virions seede to all the epithelial surfaces of the body.
ABout 9 days after exposure abrubt onset of illness with cough, running nose, and inflamed conjunctivae. Immune repsonse contribute to respiratory damage., malaise and fever. Occasionally central nervous system involvement. Develops in the first week after the appearacne of the rash. This is the main reason for vaccination.