what is use to seal the egg shell after the inoculation
Answers
The most convenient method of propagating Newcastle disease virus in the laboratory is by the inoculation of the allantoic cavity of embryonated eggs.
All strains of Newcastle disease virus will grow in the cells lining the allantoic cavity. The virus enters these cells where it multiplies. As the cells are disrupted the virus is shed into the allantoic fluid.
Virulent strains of the virus will invade cells beyond the lining of the allantoic cavity and kill the embryo. The time taken for this to occur is the basis of the “Mean Death Time Assays”, which indicate the level of virulence.
The avirulent I-2 strain of Newcastle disease virus will not kill embryos inoculated by the allantoic cavity.
Inoculation of the allantoic cavity of embryonated eggs is a technique used in the following procedures:
1. Newcastle disease vaccine production
2. Establishing the infectivity titre of a suspension of Newcastle disease virus.
3. Isolation of Newcastle disease virus from field specimens for laboratory diagnosis.