Viral Diseases and Immunity

The gag gene is encoded as a large gag-pol protein with another gene then cleaved to the precursor protein assemblin, which is then cleaved to Gag. It is involved in virion assembly and produces some of the capsid and nucleocapsid proteins. It does not encode for the lipid bilayer of the virus.

The window period is the period between the onset of HIV infection and the appearance of detectable antibodies to the virus. The purpose of the p24 antigen portion of the test is to detect HIV before body has made antibodies, i.e., in the window period.

For the HIV infection to occur the cell fusion is essential. This is done by the transmembrane glycoprotein gp41. HIV-1 utilises two major co-receptors along with CD4 to bind to, fuse with, and enter target cells.

HAART is used to suppress HIV viral replication and the progression of HIV disease. It conjoins three or more different drugs, such as two nucleoside reverse transcriptase inhibitors (NRTIs) and a protease inhibitor. These HAART regimens have proven to reduce the amount of active virus and in many case.

Epstein-Barr virus is associated with Burkitt's lymphoma and with naso-pharyngeal carcinoma.

A glioma is a type of tumor that starts in the brain or spine. It is called a glioma because it arises from glial cells. An increased incidence in gliomas has no association with HIV infection.

In case of HIV infection this test finds either the RNA of the HIV virus or the HIV DNA in white blood cells infected with the virus. The PCR test is very useful to find a very recent infection.

In complete DiGeorge syndrome there is a total failure of the thymus to develop and thus neither CD4-positive T-cells nor CD8-positive T-cells are formed. Note, however, that most cases of DiGeorge syndrome are 'partial' with some thymic development and thus not a complete absence of T-cells.

A glioma is a type of tumor that starts in the brain or spine. It is called a glioma because it arises from glial cells. An increased incidence in gliomas has no association with HIV infection.

In case of AIDS, the virus affects the immune system, damages its functions and leads to death.

Malarial protozoans enter the body through mosquito bite and travel to the liver and the RBCs.

TMV is a ssDNA virus.

 HIV infection is associated with the progressive loss of CD4(+) T cells through their destruction or decreased production.

Rabies is a viral disease that causes acute encephalitis in warm blooded animals. Negri bodies are eosinophilic sharply outlined pathognomonic inclusion bodies found in the cytoplasm of certain nerve cells containing the virus of rabies especially in Ammon's horn of the hippocampus. It is also found in the cerebellar cortex of postmortem brain samples of rabies victims. They consist ribonuclear proteins produced by the virus.

The virus particle consists an outer lipid envelope and an icosahedral nucleocapsid core composed of protein. These virions are 42 nm in diameter and are sometimes referred to as Dane particles. This is known as the Dane particle as it was discovered by Dane in 1970. The nucleocapsid encloses the viral DNA and a DNA polymerase that has reverse transcriptase activity.