Sunday 8 December 2013

Potential HIV "cure" set back

Back in Berlin 2007, an HIV-positive man called Timothy Ray Brown was given a bone marrow transplant using cells from a donor naturally genetically resistant to the virus. Brown, known as the "Berlin Patient", has remained free of the virus since the procedure. 

This incredible result was an impressive result of chance - Brown required a bone marrow transplant to treat leukemia, and the doctors managed to find a donor who not only matched close enough for the transplant to be accepted but carried a mutation in the CCR5 gene. In Europeans, this deletion mutation occurs in both copies of the gene in 1% of the population and significantly reduces the ability of the HIV virus to enter CD4+ T cells (a type of immune cell).

Six years after this procedure, and Brown still remains virus free. The success of this procedure led to great hopes in the treatment of HIV in patients all over the world, although the difficulty of finding donor who matched close enough for transplant and had the CCR5 mutation is an enormous hurdle to overcome.
Are our methods for detecting HIV sensitive enough?

Two HIV+ patients in Boston, one in 2008 and the other in 2010, also received bone marrow transplants to treat leukemia. However their donors did not have the resistance mutation. To the surprise of many doctors, the patients appeared virus free after the procedures and remained that way for years even after discontinuing antiretroviral medication.

Unfortunately now it has been announced that the virus has rebound in both patients. As well as being devastating news to the patients and their families, it has much wider repercussions in the medical world.

After receiving the transplants, the men underwent all sorts of test to measure their viral loads and none were able to detect HIV presence. Yet now it is clear the virus was there all along. This means that the tests we have are not good enough.

There is also the disturbing realisation that people previously described as "cured" may still have the virus lurking somewhere within them. Patients such as the infant cured of HIV will have to be carefully monitored for viral resurgence and those who have seen their viral load reduced to "none" on medication should refrain from discontinuing.

This is a huge set back in research into potential cures for HIV, the virus is even more persistent than previously thought and the design of more sensitive test for viral load is required urgently.

Sunday 1 December 2013

Paper warning of dangers of GM corn retracted

Back in September of last year, a paper published in the peer-reviewed journal Food and Chemical Toxicology linked the genetically modified corn NK603 to adverse health effects in rats. Although previous long term studies had shown no ill-effects of a diet of GM crops, these two year long study disturbingly showed higher rate of cancer and reduced lifespan of rats fed on NK603 in comparison to the control groups. Publication of these findings led to further public fear and confusion over the actual risk of GM crops.

At the time, many scientists questioned the reliability of the paper "Long-term toxicity of a Roundup herbicide and a Roundup-tolerant genetically modified maize". Cited were issues with the methodology, very low statistical significance linked to small sample size and, significantly, that the strain of rats used in the study (known as Sprague-Dawley rats) are incredibly susceptible to the spontaneous growth of tumors as they age. The $1.4 million study was also plagued with accusations of bias, with conflicts of interests on both the sides of its supporters and those who petitioned for its removal from the journal.

NK603 is resistant to the herbicide glyphosate
and approved for human consumption


On the 28th November 2013 however, the journal announced the redaction of the paper, following analysis of the data and an investigation into the peer-review process it went through. In a press conference, Corinne Lepage, a Member of the European Parliament and a founding member of one of the funding bodies behind the paper, explained that the retraction of the paper "will not make these questions [about the safety of GM crops] disappear".

It is entirely necessary that further studies into the possible risks of GM crops (and the benefits that they generate too) are carried out. However it is vital that these are performed with the best scientific rigor, to prevent further confusion for the public and embarrassment to those working in these fields.

Removal of the paper is unlikely to dampen the public concern over GM crops that its initial publication generated. Like the now decades-old vaccine scares, the general media finds it much easier to promote scare stories involving small, unreliable (or, in some terrible cases, fabricated) data than to rationally and delicately explain finding to the lay-person. This means that it is on the shoulders of the scientific community to ethically and without bias report real findings in such a way that any rational person is able to determine their reliability for themselves.