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
Answer:

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

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
Answer:

Question 2. HIV infection
Answer:

• 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

Question 3. ELISA test
Answer:

• 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
Answer:

Question 5. Window period
Answer:

• 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
Answer:

• 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
Answer:

• 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.
Answer:

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?
Answer:

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: