Skip to main content

Our ancestors wiped out HIV-type virus 11 million years ago (hindu, )

Evidence of defence mechanism that involved manipulating the function of one of the virus’s genes, turning virus against itself.

Our ancestors may have eliminated a primordial Human Immunodeficiency Virus (HIV) type virus around 11 million years ago, according to a new study that examined fossil DNA to find out when ancient viruses were at their peak.

Researchers from The Rockefeller University in the United States suggest that our primate ancestors evolved a defence mechanism that involved manipulating the function of one of the virus’s genes, turning the virus against itself.

Providing a wealth of insight

“Analysing viral fossils can provide a wealth of insight into events that occurred in the distant past,” said Paul Bieniasz, from the Howard Hughes Medical Institute in the U.S.

“This study is an example of how viruses themselves can provide the genetic material that animals use to combat them, sometimes leading to viral extinction,” said Dr. Bieniasz.

Retroviruses, a class of viruses that include the HIV are abundant in nature and can leave lasting traces of their existence if they infect cells of the germ line.

Unlike other viruses, they include a step in their life cycle where their genetic material is integrated into the genome of their host — creating a genetic fossil record that can be preserved in the genomes of the host and its evolutionary descendants.

To examine how extinct viral lineages could once have been eliminated, researchers analysed retroviral fossils left by human endogenous retrovirus T (HERV-T), which replicated in our primate ancestors for about 25 million years before it was eradicated about 11 million years ago.

Working with Robert Gifford from the University of Glasgow in the U,K,, the team first compiled a near-complete catalogue of HERV-T fossils in old-world monkey and ape genomes.

They then reconstructed the HERV-T retrovirus’ outer envelope protein — a molecule that allows a virus particle to bind to cells and begin the viral replication cycle.

“Our analyses suggested that HERV-T likely used a cell-surface protein called MCT-1 to bind to cells and infect ancient old-world primates,” said Daniel Blanco-Melo, a former graduate student in the Bieniasz lab.

Fossilised gene

The researches also identified a fossilised HERV-T gene in the genomes of contemporary humans that was absent in more distantly-related primate genomes.

They found that this gene encoded a well-preserved envelope protein that can block retroviral infection by depleting MCT-1 from cell surfaces.

“It appears this gene was integrated into the ancestral primate genome around 13 to 19 million years ago, and we believe it was around this time that the function of this gene switched,” said Mr. Blanco-Melo.

“Ancestral hominids evolved a defence mechanism against HERV-T, using the virus’s own gene against itself, eventually leading to its extinction,” he added.

Popular posts from this blog

Cloud seeding

Demonstrating the function of the flare rack that carries silver iodide for cloud-seeding through an aircraft. 
Water is essential for life on the earth. Precipitation from the skies is the only source for it. India and the rest of Asia are dependent on the monsoons for rains. While the South West Monsoon is the main source for India as a whole, Tamil Nadu and coastal areas of South Andhra Pradesh get the benefit of the North East Monsoon, which is just a less dependable beat on the reversal of the South West Monsoon winds.

SC asks Centre to strike a balance on Rohingya issue (.hindu)

Supreme Court orally indicates that the government should not deport Rohingya “now” as the Centre prevails over it to not record any such views in its formal order, citing “international ramifications”.

The Supreme Court on Friday came close to ordering the government not to deport the Rohingya.

It finally settled on merely observing that a balance should be struck between humanitarian concern for the community and the country's national security and economic interests.

The court was hearing a bunch of petitions, one filed by persons within the Rohingya community, against a proposed move to deport over 40,000 Rohingya refugees. A three-judge Bench, led by Chief Justice of India Dipak Misra, began by orally indicating that the government should not deport Rohingya “now”, but the government prevailed on the court to not pass any formal order, citing “international ramifications”. With this, the status quo continues even though the court gave the community liberty to approach it in …

India’s criminal wastage: over 10 million works under MGNREGA incomplete or abandoned (hindu)

In the last three and half years, the rate of work completion under the Mahatma Gandhi National Rural Employment Guarantee Act (MGNREGA) has drastically declined, leading to wastage of public money and leaving villages more prone to drought. This could also be a reason for people moving out of the programme.

At a time when more than one-third of India’s districts are reeling under a drought-like situation due to deficit rainfall, here comes another bad news. The works started under the MGNREGA—close to 80 per cent related to water conservation, irrigation and land development—are increasingly not being completed or in practice, abandoned.

Going by the data (as on October 12) in the Ministry of Rural Development’s website, which tracks progress of MGNREGA through a comprehensive MIS, 10.4 million works have not been completed since April 2014. In the last three and half years, 39.7 million works were started under the programme. Going by the stipulation under the programme, close to 7…