Context
Recent studies showed ‘zombie’ areas in genome helped in human evolution
About Endogenous Retroviruses (ERVs)
- A group of viruses within the human genome that are inherited by successive generations.
- Retrovirus Invasions
- Retrovirus invasions can disrupt the genome, creating ‘zombie’ areas called endogenous retroviruses (ERVs).
- ERVs typically cannot replicate or produce functional proteins due to missing regulatory regions.
- If ERVs integrate into germ cells (cells producing gametes like sperm and ova), they can be inherited by the host’s offspring, although this is rare.
- Evolution of ERVs
- Over the years of mammalian evolution, retroviruses have left genomic elements, acting as genetic fossils of past infections.
- These elements have lost the ability to produce viruses, but they have influenced the evolution of their hosts.
- Approximately 8% of the human genome is composed of ERVs.
- Influence on the Human Genome
- Syncytins, a class of genes are believed to descend from ERVs.
- Syncytins play a crucial role in placental development.
- ERVs are involved in cellular differentiation processes.
- Human ERV element LTR10, integrated into the genome about 30 million years ago, which significantly influences tumour formation.
Source:
The Hindu
Previous Year Question
Consider the following statements:
1. Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
2. Common cold is sometime caused by an adenovirus whereas AIDS is caused by a retrovirus.
[UPSC Civil Services Exam – 2021 Prelims]
Which of the statements given above is/are correct?
(a) 1 only
(b) 2 only
(c) Both 1 and 2
(d) Neither 1 nor 2
Answer: (b)
