UPSC-CMS 2024 - Microbiology PYQs Practice Questions

Q: Consider the following statements regarding dengue virus : 1. It has four distinct serotypes. 2. Infection with any one serotype confers lifelong immunity for that virus serotype. 3. Secondary infection with dengue serotype 2 leads to severe form of dengue. Which of the statements given above are correct?

1 and 2 only. ***1 and 2 only*** - Dengue virus indeed has **four distinct serotypes (DENV-1, DENV-2, DENV-3, DENV-4)**, explaining different epidemiological patterns and reinfections. - Infection with one serotype provides **lifelong homologous immunity** against that specific serotype, meaning a person will not get sick again from the same serotype. *2 and 3 only* - While statement 2 is correct, statement 3 is not universally true, as severe dengue can occur with secondary infection of any serotype, although **DENV-2** and **DENV-3** are more frequently implicated. - This option incorrectly excludes the fact that dengue has four distinct serotypes, which is a fundamental aspect of its biology and epidemiology. *1 and 3 only* - While statement 1 is correct, statement 3 is a simplification; severe dengue in secondary infections is due to **antibody-dependent enhancement (ADE)**, which can happen with various heterologous serotypes, not exclusively DENV-2. - This option incorrectly implies that infection with one serotype does not confer lifelong immunity to that specific serotype, which is a key characteristic of dengue immunity. *1, 2 and 3* - This option is incorrect because statement 3, while partially true, is too absolute. Severe dengue can be linked to **DENV-2** or **DENV-3** in secondary infections but isn't exclusive to DENV-2. - The risk of severe dengue is due to a **secondary infection** with a **heterologous serotype**, not specifically serotype 2, though DENV-2 often causes more severe illness in secondary infections. [Practice more Microbiology PYQs on OnCourse]

Q: Monkeypox, a viral zoonotic disease, is caused by

a double-stranded DNA virus. ***a double-stranded DNA virus*** - Monkeypox is caused by the **monkeypox virus (MPXV)**, which belongs to the **Poxviridae family**. - Viruses in the Poxviridae family are known for having a **double-stranded DNA genome**. *a single-stranded RNA virus* - Many common viruses, such as **SARS-CoV-2 (COVID-19)**, **influenza virus**, and **HIV**, are single-stranded RNA viruses. - This genomic structure is fundamentally different from that of the monkeypox virus. *a single-stranded DNA virus* - Viruses like **Parvovirus B19** are single-stranded DNA viruses. - This type of genome is less common in human pathogens compared to double-stranded DNA or RNA viruses. *a double-stranded RNA virus* - Viruses such as **rotaviruses**, which cause gastroenteritis, are double-stranded RNA viruses. - While also double-stranded, its RNA nature distinguishes it from the DNA genome of monkeypox virus. [Practice more Microbiology PYQs on OnCourse]

Question 1

Consider the following statements regarding dengue virus :

1. It has four distinct serotypes.
2. Infection with any one serotype confers lifelong immunity for that virus serotype.
3. Secondary infection with dengue serotype 2 leads to severe form of dengue. Which of the statements given above are correct?

Accepted Answer

1 and 2 only

Answer

2 and 3 only

Answer

1 and 3 only

Answer

1, 2 and 3

Question 2

Monkeypox, a viral zoonotic disease, is caused by

Accepted Answer

a double-stranded DNA virus

Answer

a single-stranded RNA virus

Answer

a single-stranded DNA virus

Answer

a double-stranded RNA virus

UPSC-CMS 2024 — Microbiology