Test: Animal Virus Replication - MCAT MCQ

Null infection represents the cells which do not have appropriate receptors for a particular virus, and thus cannot interact with virus particle. The viral genome is artificially introduced into such cells in the laboratory to produce progenies.

The infection of a cell with a variety of DNA viruses results in the change in a wide variety of properties of the cell and the cells may undergo rapid multiplication. This results in the transformation of cells and hence transforming infection.

UL37x1 is a protein encoded by human cytomegalovirus which is a herpes virus. The protein inhibits the apoptosis of infected cells, which permits the virus to establish a long-lasting infection.

Rubella virus, which belongs to the family Togaviridae, expresses proteins that promote the cell death by apoptosis. Vaccinia virus, myxoma virus, herpes simplex virus, etc. are the viruses that inhibit the cell death by apoptosis.

Meningitis is a type of bacterial infection. The interactions between viral and cells can be classified into acutely cytopathogenic, persistent, null, latent, abortive, transforming infections.

Abortive infection causes a reduction in the total yield of virus particles (sometimes to zero). The quality of the progeny, if produced, maybe deficient as the cells do not replicate that virus with equal efficiency.

The term latent is defined as existing but not exhibited. In terms of the virus-infected cell, it means that the viral genome is present but no infectious progeny is produced. Adeno-associated virus, herpesvirus exhibits latency.

Persistent infections are the infections that cause or result in the continuous production of infectious viruses. This is achieved either by the survival of the infected cells or by a situation in which a minority of cells are initially infected and the spread of the virus is limited.

Cytopathogenic infections are also called lytic infections as the cell dies due to lysis. But lytic is not the accurate term, as in some infection cells die without being lysed, that is, by apoptosis or programmed cell death.

Apoptosis is the process that regulates cell numbers during development. The unique feature of apoptosis is that the dying cell remains intact and its contents stay within the plasma membrane.