R5X4 HIV viruses

HIV-1 utilizes two major co-receptors along with CD4 to bind to, fuse with, and enter target cells; these co-receptors are CCR5 and CXCR4, which are also receptors for certain endogenous chemokines.

Strains of HIV that utilize CCR5 as a co-receptor are referred to as R5 viruses.

Strains of HIV that utilize CXCR4 are referred to as X4 viruses.

Many virus strains are dual tropic in that they utilize both CCR5 and CXCR4; these are referred to as R5X4 viruses.

Part 1 HIV Multiple chioce questions

1q: HIV belongs to which family of viruses ?


a. retroviridae
b. reoviridae
c. calci viruses
d. picorna viruses

answer a . retroviridae

2q: HIV belongs to which subfamily of viruses ?


a. papova viruses
b. pox viruses
c. herpes viruses
d. lenti viruses

answer d . lenti viruses

3q: any HIV infected individual with a CD4+ T cell count of less than ___________
Has AIDS by definition ?


a. less than 200/microliter
b. less than 250/microliter
c. less than 300/microliter
d. less than 150/microliter

answer a . less than 200/microliter

4q: which of the following does not belong to the retroviridae family ?


a. HTLV-1
b. HTLV-2
c. HIV-1
d. HIV-2
e. CMV

answer e . CMV belongs to the human herpes family viruses group

5q: which of the following is the most common cause of HIV disease throughout the world ?


a. HIV-1
b. HIV-2
c. Both of them have equal incidence
d. HTLV-1

answer a . HIV-1 . it is the most common even in USA