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HIV AND AIDS Part 1 - VIROLOGY (36 MCQs)



1) AIDS is CD4+ T cell count less than -------------- /uL

a. 500

b. 250

c. 200

d. 100





Ans: (c)

Any HIV-infected individual with a CD4+ T cell count of less than 200/uL has AIDS by definition, regardless of the presence of symptoms or opportunistic diseases. The CD4+ T lymphocytes and CD4+ cells of monocyte lineage are the main targets of HIV. HIV belongs to the family of human retroviruses (retroviridae) and the subfamily of lentiviruses.



2) The master regulator of the immune system

a. Pituitary gland

b. CD4+ T cells

c. CD8+ T cells

d. GM-CSF

e. Neutrophils





Ans: (b)

The CD4+ T cell is the master regulator. CD4+ T cells secrete cytokines. By secreting cytokines, CD4+ T cells influence the function of virtually all other cells of the immune system, including other T cells, B cells, macrophages, and NK cells. The HIV cripples the immune system by destroying CD4+ T cells.

CD8+ T cells function mainly as cytotoxic cells to kill other cells.



3) The genetic information of the HIV is encoded by

a. DNA

b. RNA

c. Both

d. Neither



Ans: (b)


A central belief of molecular biology is that information passes unidirectionally from DNA to RNA to protein. The retroviruses are called so because RNA, rather than DNA, encodes their genetic information. Retroviruses contain an RNA-dependent DNA polymerase (a reverse transcriptase) that directs the synthesis of a DNA form of the viral genome from the RNA.



4) Most common cause of HIV disease throughout the world

a. Transforming retroviruses

b. HIV-1

c. HIV-2

d. HIV - 3



Ans: (b)


There are four human retroviruses: the transforming retroviruses (human T lymphotropic viruses - HTLV 1 and HTLV 2) and cytopathic viruses (HIV-1 and HIV-2).

HIV-1 infection in humans originated from chimpanzees. HIV was isolated by Luc Montagnier from Pasteur institute, Paris (1983) and by Robert Gallo (1984). The most common type is HIV-1. It is a 90 to 120 nm sized single stranded RNA virus. HIV-1 is more pathogenic than HIV-2. The subtype C is prevalent in India.



5) Which group is responsible for most of the infections in the world?

a. M

b. O

c. N

d. Circulating recombinant forms



Ans: (a)

There are two groups of HIV-1. Group M (major) is responsible for most of the infections in the world.
Group O (outlier) is a relatively rare form found originally in Cameroon, Gabon, and France. There is a third group (group N) first identified in a Cameroonian woman with AIDS.

The M group comprises eight subtypes or clades, designated A, B, C, D, F, G, H, and J, as well as four major circulating recombinant forms (CRFs). Subtype C viruses (of the M group) are the most common form worldwide. Subtype C is prevalent in India.
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