Human immunodeficiency virus( HIV ):

College of Medicine Microbiology
Medical Virology
Human immunodeficiency virus( HIV ):
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General properties:
• It belongs to retroviruses.
• The virus has spherical shape.
• Genome of virus is ssRNA.
• It has icosahedral symmetry.
• It has envelope with spikes
Biological structure of HIV:
• Envelope: the virus is surrounding by bilayer lipid envelope that covered by projected spikes (glycoprotein: gp41, gp120)which may act as attachment sites. (N.B: HIV undergoes from high rate of antigenic variation in envelope glycoproteins).
• Capsid proteins: consist of several proteins as capsid protein(p24) and matrix protein (p17).
• Genome consist of two copies of (+)ssRNA(diploid).
• Core protein: contain many enzymes as reverse transcriptase (RTase), integrase.
Two types of HIV :
1. HIV-I has 9 subtypes. It is responsible for most cases of acquired immune deficiency syndrome (AIDS).
2. HIV-2 has 5 subtype , it is less commonly and less virulent.
• AIDS was first described as disease in 1981 and the virus was isolated by end of 1983.

Mode of transmission:
• sexual contact: HIV has high affinity to semen and vaginal secretions , therefore the virus can be transmitted by anal or vaginal intercourse among homosexual and heterosexual individuals.
• Parenteral transmission; it can be transmitted by blood transfusion, or by needles or syringes such as intravascular drug uses(IVDU).
• Mother to child: HIV can be transmitted to neonate across placenta or during delivery or breast milk.
• Other methods for transmission of HIV ; fluids of body such as urine, tear, saliva.