HIV is composed of RNA, viral proteins, and host cell proteins surrounded by a lipid membrane. It belongs to the genus Lentivirus and family Retroviridae. The HIV genome contains genes like Gag, Pol, Env, Tat, Rev, Nef, Vif, Vpr, and Vpu/Vpx that encode viral proteins. HIV is transmitted sexually or through blood and can develop into AIDS, which occurs when CD4 counts fall below 200 and the immune system is severely compromised, increasing risk of infections. While there is no cure for HIV/AIDS, antiretroviral treatment can slow its progression.

1. B.Sc.I
Diversity of Microbes And Cryptogams
Unit I
HIV
DR. SWATI V. PUNDKAR
Assistant Professor
Department of Botany
Shri Shivaji Science College, Amravati
NAAC Accredited ‘A’ Grade

2. HIV (Human Immunodeficiency Virus) is composed of two strands
of RNA, 15 types of viral proteins, and a few proteins from the last
host cell it infected, all surrounded by a lipid bilayer membrane.
Genus Lentivirus
Family Retroviridae,
Subfamily Orthoretrovirinae

4. HIV genome and proteins

5. 1. Structural gene:
i. Gag gene:
 Gag gene encodes the precursor protein P55 which is cleaved
by viral protease (P10) to form matrix protein (P17), Capsid
protein (P24) and Nuncleocapsod protein (P7 & P9). Gag gene
helps to form core of virus.
ii. Pol gene:
 Pol gene encodes the precursor protein P100 which is cleaved
to form Protease (P10), reverse transcriptase and
endonuclease.
iii. Env gene:
 Env gene encodes the precursor protein gp160 which is
cleaved to form surface spike glycoprotein (gp120) and
transmembrane protein (gp41).
 Genetic variety of HIV strain resides in env

6. 2. Regulatory gene:
i. Tat gene: ( transactivator of transcription)
 It encodes transactivator protein (P14) which promotes the transcription of viral genome.
ii. Rev gene: (regulatory of expression of viral protein)
 It encodes Rev protein (P19) and promotes the expression of viral structural proteins
iii. Nef gene: ( Negative expression factors)
 It encodes precursors protein P27
 It down regulates the expression of CD4 cells, macrophage and MHC-II.
iv. Vif gene: (Virion infectivity factor)
 It encodes the precursor protein p23 and promotes the viral infectivity by suppression the
inhibitory actions of host cell proteins.
v. Vpr gene:
 It encodes the precursor protein P15.
 It promotes the transport of viral pre-initiation complex into nucleus of host cell.
vi. Vpu gene in HIV-I / Vpx gene in HIV-II

7. HIV Trasmission

9. Acquired immunodeficiency syndrome (AIDS) is a chronic, potentially life-
threatening condition caused by the human immunodeficiency virus (HIV). By
damaging your immune system, HIV interferes with your body's ability to fight infection
and disease.
HIV is a sexually transmitted infection (STI). It can also be spread by contact with
infected blood or from mother to child during pregnancy, childbirth or breast-feeding.
Without medication, it may take years before HIV weakens your immune system to the
point that you have AIDS.
There's no cure for HIV/AIDS, but medications can dramatically slow the progression
of the disease.

10. What is AIDS?
AIDS is a disease that can develop in people with HIV. It’s the most advanced stage of HIV
HIV kills CD4 cells. Healthy adults generally have a CD4 count of 500 to 1,600 per cubic millimeter. A
person with HIV whose CD4 count falls below 200 per cubic millimeter will be diagnosed with AIDS.
If AIDS does develop, it means that the immune system is severely compromised, that is, weakened
to the point where it can no longer successfully respond against most diseases and infections.
To develop AIDS, a person has to have contracted HIV. But having HIV doesn’t
necessarily mean that someone will develop AIDS.
Cases of HIV progress through three stages:
 stage 1: acute stage, the first few weeks after transmission
 stage 2: clinical latency, or chronic stage
 stage 3: AIDS