Q. Consider the following statements:
I. No virus can survive in ocean waters.
II. No virus can infect bacteria.
III. No virus can change the cellular transcriptional activity in host cells.
How many of the statements given above are correct?
Exp) Option d is the correct answer.
Statement I is incorrect: Viruses are abundant in ocean waters. Oceans are estimated to contain more than 10³⁰ viruses, making them one of the most virus-rich environments on Earth.
- The vast majority of these are bacteriophages, which infect marine bacteria.
- These viruses play a key role in regulating microbial populations, nutrient cycling, and even in carbon cycling, by influencing the death and lysis (breaking down) of microbial cells.
- Marine viruses are an active area of research in marine biology, virology, and climate science.
Statement II is incorrect: There is a well-known class of viruses called bacteriophages (or simply phages) that specifically infect bacteria.
These are widely used in research and have even found therapeutic applications (called phage therapy) to combat antibiotic-resistant bacterial infections.
Bacteriophages attach to bacterial cells, inject their genetic material, and hijack the bacterial machinery to replicate themselves.
Statement III is incorrect: Viruses are obligate intracellular parasites, meaning they rely on host cell machinery to replicate.
To achieve this, many viruses manipulate and alter the host cell’s transcriptional activity (and other cellular processes) to favor viral gene expression and replication. This can involve activating or repressing host genes, hijacking host transcription factors, or introducing their own transcriptional machinery.
Source: https://asm.org/articles/2023/june/marine-viruses-submerged-players-of-climate-chang
https://pmc.ncbi.nlm.nih.gov/articles/PMC7173423/
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