Retroviridae Flashcards
What enzyme is required for the replication of Retroviruses?
Reverse transcriptase (RNA-dependent DNA polymerase).
What is the function of reverse transcriptase?
Converts viral RNA into DNA for integration into the host genome.
What are the two major subfamilies of Retroviridae?
Lentivirus (e.g., HIV-1, HIV-2)
Oncovirus (e.g., HTLV-1, HTLV-2).
How does HIV integrate into the host genome?
Through the enzyme integrase
What is the structure of HIV?
Spherical virus with a three-layer structure containing two ssRNA copies and reverse transcriptase inside an icosahedral capsid
Which HIV proteins are used for diagnosis?
p24, gp41, gp120, gp160.
Which HIV glycoprotein is responsible for viral attachment to host cells?
gp120 binds to CD4+ receptors.
Which HIV glycoprotein is responsible for viral fusion with the host cell membrane?
gp41 facilitates membrane fusion
What are the three main stages of HIV infection?
Acute infection, clinically latent phase, and AIDS progression.
What happens during the acute phase of HIV infection?
High viral load, destruction of CD4+ T-cells, flu-like symptoms, and no detectable HIV antibodies.
How long does the clinically latent period of HIV last?
Approximately 10 years, though some patients progress faster or slower.
What defines AIDS in an HIV patient?
CD4 count <200 cells/µL or the presence of AIDS-defining illnesses.
What is the first test used for HIV screening?
Fourth-generation ELISA (antigen-antibody combination assay).
What does the fourth-generation HIV test detect?
HIV-1 and HIV-2 antibodies + p24 antigen.
What is the confirmatory test for HIV?
Western Blot (or HIV differentiation immunoassay).
Why is PCR used for diagnosing HIV in newborns?
Maternal antibodies may interfere with serologic tests.
What test monitors HIV disease progression?
HIV RNA viral load assay and CD4+ T-cell count.
What is the standard treatment for HIV?
Highly Active Antiretroviral Therapy (HAART).
What is the goal of HAART?
To suppress viral replication and slow disease progression.
What laboratory test is used to detect HIV drug resistance?
HIV genome sequencing.
What diseases are associated with HTLV-1?
Adult T-cell leukemia/lymphoma (ATLL) and HTLV-associated myelopathy (HAM/TSP)
What is the mode of transmission of HTLV-1?
Blood transfusion, sexual contact, and breastfeeding.
What is the primary method for diagnosing HTLV?
Serologic detection (ELISA, Western Blot, PCR).
A 25-year-old presents with fever, sore throat, rash, and swollen lymph nodes. He had unprotected sex recently. What is the likely stage of HIV?
Acute HIV infection
A patient has CD4 count = 180 cells/µL and Pneumocystis pneumonia. What stage is he in?
AIDS
A newborn of an HIV-positive mother tests positive for HIV antibodies. What test should be done next?
PCR for viral RNA or DNA to confirm true infection.
A patient diagnosed with HIV wants to check the effectiveness of his treatment. What test should be performed?
HIV RNA viral load test
