Biology · General Awareness

Viral Diseases and Immunity

807 Questions

Viral diseases and immunity cover the structure, transmission, and diagnosis of viruses like HIV. Questions focus on disease pathways, immune responses, and prevention. Strong knowledge here provides an edge in biology scoring.

HIV and AIDS structureVirus transmission methodsImmune system deficiencyPathogen risk groupsMedical diagnosis methods

Viral Diseases and Immunity Questions

Multiple choice

The human immunodeficiency virus (HIV) interacts with which of the following cell-surface molecules to gain entry into cells of the immune system?

  1. CD4

  2. CD19

  3. CD40 ligand

  4. CD8

  5. CD25
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

This is a major portal of entry, though not the only one. The chemokine receptors CXCR4 and CCR5 are also major portals of entry and reduce the CD4 positive helper T cell numbers dramatically (see Case 3.11 Acquired immune deficiency syndrome: Kaposi's sarcoma

Multiple choice

The HIV virus attacks T-helper cells, knocking out the body's ability to defend itself against infections. Helper CD4+ T lymphocytes recognise which of the following types of molecules on dendritic cells?

  1. HLA class I antigen

  2. HLA class III antigen

  3. Processed peptides from antigen

  4. CD8 antigen

  5. Surface immunoglobulin
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

But only if the T cell has the correct antigen specificity in the TCR AND the same HLA class II antigens.

Multiple choice

Which among the following is/are regarded as the best treatment for HIV infection?

  1. Highly active antiretroviral therapy (HAART)

  2. Integrase inhibitors

  3. Protease inhibitors

  4. Reverse transcriptase inhibitors

  5. Telomerase reverse transcriptase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

HAART is used to suppress HIV viral replication and the progression of HIV disease. It conjoins three or more different drugs such as two nucleoside reverse transcriptase inhibitors (NRTIs) and a protease inhibitor. These HAART regimens have proven to reduce the amount of active virus and in many cases.

Multiple choice

Which among the following accessory regulatory proteins of HIV is neccesary for the successful release of virions from infected cells?

  1. env

  2. pol

  3. gag

  4. vpu

  5. tev
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Vpu is specific to HIV-1. It is a class I oligomeric integral membrane phosphoprotein with numerous biological functions. Vpu is involved in CD4 degradation involving the ubiquitin proteasome pathway as well as in the successful release of virions from infected cells.

Multiple choice

Which among the following statements does NOT characterise HIV viral antigen?

  1. Serum antibodies form the first layer of protection of the host from viral infection.

  2. Recombinant viral proteins are expressed in bacteria, yeast, mammalian cells, etc.

  3. Recombinant viral protein usually contains a fusion protein.

  4. Recombinant viral antigens contain part of viral sequence.

  5. ELISAs provide a valuable tool in the detection and diagnosis of viral infection.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Antibody-based immune responses form a first layer of protection of the host from viral infection; however, in many cases a vigorous cellular immune response mediated by T-cells and NK-cells is required for effective viral clearance. When cellular immunity is unable to clear the virus, the infection can become chronic, and serum antibodies to the viral pathogen are used as first indicator for the diagnosis of the disease.

Multiple choice

Human immunodeficiency virus (HIV), the cause of AIDS, belongs to the category of

  1. single-stranded DNA (ssDNA)

  2. reverse-transcribing viruses

  3. double-stranded RNA (dsRNA)

  4. negative sense single-stranded RNA (ssRNA-)

  5. positive sense single-stranded RNA (ssRNA+)
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

These have dsDNA or ssRNA genomes and their replication includes the synthesis of DNA from RNA by the enzyme reverse transcriptase; many integrate into their host genomes. The group includes the retroviruses, of which Human immunodeficiency virus (HIV), the cause of AIDS, is a member. There is a single family of plant viruses in this group and this is characterised by a single component of circular dsDNA, the replication of which is via an RNA intermediate.

Multiple choice

Oncogenesis is the process by which normal cells are transformed into cancer cells. Which among the following viruses may have a hit and run mechanism of oncogenesis?

  1. Papillomavirus

  2. Polyomavirus

  3. Simian virus 40

  4. Adenovirus

  5. Herpesvirus
Reveal answer Fill a bubble to check yourself
E Correct answer
Explanation

Herpesvirus are much larger than the DNA viruses having a genome size of 100 to 200 kilobases. These are often co-carcinogens. They may have a hit and run mechanism of oncogenesis.

Multiple choice

Which of the following is not true regarding adeno-associated virus?

  1. It contains double-stranded DNA.

  2. It may integrate into the host chromosome.

  3. It may be associated with insertional mutagenesis when used as a gene therapy vector.

  4. It may exist in the cell as an episome.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Adeno-associated virus contains single-stranded DNA.