Retrovirus HIV Virology Short And Long Essay Question And Answers

Retrovirus HIV Important Notes

1. HIV

  • Mode of transmission
    • Sexual intercourse
    • Blood and blood products
    • Tissue and organ donation
    • Injections and injuries
    • Mother to baby
  • Clinical features
    • Low-grade fever
    • Malaise
    • Headache
    • Lymphadenopathy
    • Spontaneous resolution within weeks
    • Seroconversion illness at 3 to 6 weeks
  • Diagnosis
    • Screening test – ELISA test
    • Confirmatory test – Western blot test, polymerase chain reaction

Retrovirus HIV Short Essays

Question 1. HIV virus

HIV occurs in two main types,

  1. HIV-1
  2. HIV-2

HIV virus Morphology:

  • HIV is a spherical-enveloped virus
  • Size: 90-120 nm in diameter
  • It contains
    • Two identical copies of single-stranded RNA genome
    • Reverse transcriptase enzyme
    • Nucleocapsid surrounding the core
    • Lipoprotein envelope
    • Projecting spikes on the surface
    • Anchoring transmembrane pedicles

Retrovirus HIV Structure of Human Immunodeficiency virus

Read And Learn More: Microbiology Question and Answers

HIV virus Modes of Transmission:

There are three modes of transmission

  1. Sexual contact
  2. Parenteral transmission
  3. Perinatal transmission

HIV virus Clinical Features:

It is classified into various groups by the Center for Disease Control in Atlanta, USA

  1. Group 1- Acute HIV infection
  2. Group 2 – Asymptomatic infection
  3. Group 3- Persistent generalized lymphadenopathy
  4. Group 4- Symptomatic HIV infection

HIV virus Oral Manifestations:

  • Greater risk for bacterial, viral, and fungal infections
  • Dental caries
  • Gingivitis
  • Acute necrotizing ulcerative gingivitis
  • Herpes Simplex infections
  • Hairy leukoplakia
  • Candidiasis

HIV virus Diagnosis:

  • Immunological tests:
    • Total leucocyte count
    • Lymphocytes count
    • T cell subset assays
    • Platelet count
    • Raised IgG and IgA levels
    • Diminished CM1
    • Lymph node biopsy
  • Specific Tests:
    • Antigen detection
    • Virus Isolation
    • Polymerase chain reaction
    • Antibody detection

HIV virus Screening Tests:

  • ELISA test
  • Karpastest
  • Rapid tests
  • Indirect immunofluorescence

HIV virus Confirmatory Tests:

  • Western blot test

Retrovirus HIV Short Question And Answers

Question 1. Mention modes of transmission of infection of HIV

Retrovirus HIV - Modes of transmission of infection of HIV

Question 2. HIV infection

  • Human immunodeficiency virus ( HIV] is the etiological agent for AIDS
  • HIV infects all cells
  • It infects primarily the CD4+ lymphocytes
  • The Center for Disease Control in Atlanta, USA, has classified the clinical course of HIV infection into various groups

Retrovirus HIV - HIV infections

Question 3. ELISA test

  • Most widely used screening test
  • It is highly sensitive and specific.
  • Direct solid phase antiglobulin ELISA is the method most commonly used for which commercial test kits are available.
  • The antigen is coated on the microtiter wells (or) another suitable solid surface.
  • The test serum is added and if antibodies are present it binds to the antigen.
  • After washing away the unbound serum, antihuman immunoglobulin linked to the suitable enzyme is added followed by color forming substrate.
  • If the test serum contains anti-HIV antibodies a visible (or) photometrical detectable color is formed which is read visually (or) by an ELISA reader.
  • ELISA has a sensitivity of over 99.5%
  • It is extremely good screening test
  • Commercial ELISA test kits contain both HIV 1 and HIV 2 antigens.

Question 4. Mention opportunistic infections associated with HIV infection

Retrovirus HIV Opportunistic infections associated with HIV infection

Question 5. Window period

  • After infection, for antibodies to appear it may take 2-8 weeks to months.
  • IgM antibodies appear first usually in about 3-4 weeks after infection and disappear in 8-10 weeks
  • IgG antibodies appear later about 5-6 weeks after infection and persist throughout
  • During part of this period, the individual may be highly infectious
  • This seronegative infective stage is known as the window period
  • Infection can be detected during the window period by p24 assay

Question 6. Rapid tests for HIV infection

  • A number of rapid tests have been introduced for the purpose of testing single samples quickly
  • They take less than 30 minutes
  • They don’t require any expensive equipment
  • These tests include:
    • Dot-blot assay
    • Particle agglutination
    • HIV spot
    • Comb tests
  • Tests using finger-pricked blood, saliva, and urine have also been developed

Question 7. Western blot test

  • Most widely used confirmatory test for HIV.
  • In this test, HIV proteins are separated according to their electrophoretic mobility and molecular weight by polyacrylamide gel electrophoresis.
  • These separated proteins are bloated on the strips of nitrocellulose paper. These strips are reacted with test sera and then with enzyme-conjugated antihuman globulin.
  • Antibodies to HIV protein present in test serum combine with all (or) any fragment of HIV.
  • These strips are washed and treated with enzyme-conjugated antihuman gammaglobulin, then a suitable substrate is added that produces colour bands.
  • The position of the band on the strip indicates the antigen with which the antibody has reacted.
  • In the positive serum, bands will be seen with multiple proteins typically with p24, p31, gp41, gpl20 (or) gpl60.

Question 8. Draw labelled diagram of HIV.

Bacteriophage Important Notes

1. Bacteriophage

  • They are viruses that infect bacteria
  • Helps in the transmission of genetic information between bacteria by transduction

Bacteriophage Short Essays

Question 1. Bacteriophage?

The viruses that infect bacteria are known as bacterio-phages

Bacteriophage Morphology:

Bacteriophages are tadpole-shaped and are made up of

1. A hexagonal head

  • The head consists of a tightly packed core of nucleic acid surrounded by a protein coat or capsid
  • The size varies from 28 nm – 100 nm.

2. A cylindrical tail and

  • The tail is composed of a hollow core, a contractile sheath surrounding the core

3. Baseplate.

  • Terminal base plate which has attached to its prongs, tail fibers or both.
  • Bacteriophages that infect E.Coli called T- even phages (T2, T4, T6) traditionally serve as the prototypes in describing the properties of bacteriophages.
  • They possess double-stranded DNA.

Bacteriophage Significance:

Bactriophage -Signification of Bactriophage

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