MadSci Network: Cell Biology

Re: Could HeLa cells be linked with the emergence of retroviruses in humans?

Date: Tue Mar 20 11:51:59 2001
Posted By: Doug Reed, Faculty, Toxinology & Aerobiology, USAMRIID
Area of science: Cell Biology
ID: 985072403.Cb

The quick and simple answer is no, Hela cells are not responsible for the "emergence" of retroviruses in humans. I put quote around emergence to emphasize the fact that retroviruses did not "emerge" in humans the 20th century - in fact there is no evidence that retroviruses have recently emerged and are not just as old as other virus types. It would instead be factually correct to say that retroviruses were discovered in the latter half of the 20th century and samples from frozen tissues in the middle part of the 20th century have been found to contain retroviruses. Retroviruses exist in the genome of all species - including humans and even bacteria. There is no reason to assume that humans were somehow special and distinct from all other life on the planet prior to the mid-1950s in regards to retroviruses.

First, let me say that I am not aware of any human vaccines, pharmaceuticals, hormones, whatever that have been developed in Hela cells. I am not saying they don't exist - but I am not aware of them. Your arguement would still suppose that chimpanzee cells (or some other species) harboring a retrovirus were co-cultured with Hela cells (intentionally or by accident) and that these HIV-containing Hela cells then found their way into yet another cell culture dish and resulted in the transmission of retroviruses into humans. While certainly possible it is unlikely. Hela cells do contain a human papilloma virus (HPV), which is a retrovirus. HPV can cause of cervical cancer in women. However there is no evidence that HPV came from another species or is a relatively "new" virus.

I am aware of Richard Hooper's arguement that HIV entered the human population by way of chimpanzee cells that were used to generate the oral poliovirus vaccine that was clinically tested in Africa. However this arguement presupposes a number of facts. First, that chimp cells were used or somehow contaminated cultures of other cells. No one has ever come forward to make such an admission (in fact they vehemently deny it) and frozen samples that have been tested are negative for HIV and the related monkey virus SIV. Secondly, while samples containing HIV have been identified from Africa in the 1950s during the time of the trials, those samples came from areas outside of the vaccine trial. Analysis of the sequence of the HIV in those samples led to the conclusion that HIV had already existed in humans for some time prior to the poliovirus trials. Third, Hooper's arguement supposes that the HIV virus is a direct descendant of the related monkey viruses. While gene sequences of HIV and SIV are related enough that it supports the monkey to man hypothesis the fact remains that there is no "smoking gun" that can definitely prove that the monkey SIV did in fact make such a jump. Certainly other viruses can jump species (influenza comes to mind) but they remain sufficiently similar that they still infect the original species - while HIV does not cause disease in monkeys. One could argue that HIV evolved and can therefore no longer infect monkeys but that also remains unproven. If one assumes that the HIV virus passed from monkeys to man it remains far simpler to imagine that someone butchering an infected monkey (monkey is a popular meat in Africa) became infected through contact with the blood.

The bottom line is this - while your notion that Hela cells could have transmitted a retrovirus to humans is possible it is a very unlikely. Retroviruses may have only "recently" been discovered but remember that the field of Virology itself is less than one hundred years old!

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