♥ Virology

Friday, January 30, 2009

6:41 PM

Methods of studying viruses
Isolation and cultivation (I) - In vivo
Animals and eggs are the first method used for virus cultivation. Suitable living mammals are chosen for cultivation of viruses. Only healthy animal that are free from any communicable disease are selected. The specific virus then can be introduced into the healthy animals. Examples of animal selected for virus cultivation are chimpanzees, mouse, sheep and rabbits. The animals are then slaughtered at the end of incubation period and are washed thoroughly and viruses are obtained from them. However, this method are inconvenient, it also concerns the safety in handling animals and animal rights.

Animal viruses can be cultivated using chick embryo technique whereby fertile hen eggs are selected. The eggs must not be more than 12 days old.
Preparation of egg for virus cultivation:
1. The shell surface is disinfected with iodine
2. Shell surface penetrated with a small sterile drill
3. After inoculation, the drill hole is sealed with gelatine & the egg is incubated
4. Virus may be able to region.

Cultivation of plant viruses
The leaves of the plant are mechanically inoculated by rubbing with a mixture of viruses and an abrasive. The virus would directly ntact the plasma membrane and infect the exposed host cells when the cell walls are broken by the abrasive. The role of the abrasive is often done by insects that suck of crush plant leaves and thus transmit viruses.

Due to rapid death of cells in the infected area, a localized necrotic lesion would develop and even if lesions does not occurs, the infected plant may show symptoms like change in pigmentation, etc. A picture of a plant infected with tobacco mosaic virus is shown.