Context
Most viruses can’t really affect the genome but retroviruses can integrate and reshape the genomes of the hosts they infect.
About
- A virus is an infectious microbe which includes a section of nucleic acid (either DNA or RNA) surrounded by a protein coat referred to as capsid.
- Viruses are not taken into consideration living organisms due to the fact they can’t perform metabolic procedures on their own.
- A virus cannot reflect alone; instead, it should infect cells and use additives of the host cell to make copies of itself.
- Often, a deadly disease ends up killing the host cell in the manner, inflicting harm to the host organism.
- Well-regarded examples of viruses inflicting human disease encompass AIDS, COVID-19, measles and smallpox.
Retrovirus
- Retroviruses have an RNA genome; can opposite-transcribe it to DNA and for that reason insert it into the host’s genome.
- This integration may be pretty solid, permitting the virus to persist inside the host for long durations.
- Types and Examples: There are numerous varieties of retroviruses, along with Human Immunodeficiency Virus (HIV), which causes AIDS and the Human T-cell Leukemia Virus (HTLV), that’s related to certain sorts of most cancers.
Endogenous Retroviruses (ERVs)
- The retrovirus invasions can occasionally reduce to rubble the mixing technique, inflicting ‘zombie’ areas in the host’s genome. These components are called endogenous retroviruses (ERVs).
- ERVs usually can’t reflect and produce useful proteins given that they lack their regulatory areas.
- If the integrations contain the germ cells — i.e. People who produce the gametes, sperm cells and ova — the host could be able to transmit its ERVs to its offspring. This happens in rare instances.
- Evolution: Over the tens of lots of years of mammalian evolution, many retroviruses have left some of the genomic factors in the genome, form of the genetic fossils of early infections.
- These factors have long lost the ability to produce viruses but researchers accept as true that they have performed a big hand inside the evolution in their hosts.
- Around 8% of the human genome is composed of ERVs.
Influence on Human Genome
- A right instance in there has an effect on the syncytins, a category of genes concept to be descended from an ERV.
- Syncytins are critical genes concerned in placental development; many ERVs are also fairly expressed inside the placenta.
- These genes in the beginning got here from viruses and had been received by means of risk as the mammalian host evolved.
- But at some point they have become essential for the host because they helped create the placenta.
- Over time, the authentic ERV’s envelope gene (env) changed into notion to be modified or changed with the aid of new versions, forming the syncytin genes as visible today in one-of-a-kind mammal species.
- Tumours in colorectal cancer: ERVs are also involved in cellular-type differentiation.
- Researchers counseled that one human ERV detail — or a portion of its DNA — referred to as LTR10 considerably impacts the formation of tumours in colorectal most cancers.
- The LTR10 retroelement appears to have been incorporated into the genome a few 30 million years ago.
- The retroelement’s presence should produce huge genomic modifications that could in turn have an effect on the expression of the genes involved in tumour formation.
Significance of the Study
- In future, as studies techniques continue to increase, scientists might also find extra exquisite insights into the evolutionary significance of ERVs and their contribution to human biology.
- Such expertise will result in breakthroughs in regenerative medication, most cancer treatment options, and customized medicinal drugs, improving understanding of human health and evolution.
Source: The Hindu
UPSC Mains Practice Question
Q. Consider the following statements:
- Adenoviruses have single-stranded DNA genomes whereas retroviruses have double-stranded DNA genomes.
- Common cold is sometimes caused by an adenovirus whereas AIDS is caused by a retrovirus.
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
Ans: (b)