What are the 5 routes of viral inoculation into an embryonated egg? Describe reason for each type of inoculation and ideal age of embryo for each type.
1. yolk sac - 5 to 7 day old embryo, used for togaviruses, avian enterovirus.
2. CAM - chorioallantoic membrane, 9 to 12 day old embryo, used for poxviruses, some herpes viruses.
3. amniotic route - 7 to 13 day old embryo, used for influenza A.
4. allantoic route - 7 to 13 day old embryo, used for influenza A, Newcastle disease virus, infectious bronchitis virus.
5. intravenous route - 10 to 12 day old embryo, used for ovine orbivirus (bluetongue).