Posts Tagged ‘foamy virus’

When dinner could kill you: smoked chimpanzee, anyone?

14 January, 2012

ProMED Mail this morning had a rather alarming item: “BUSHMEAT TRADE, DISEASE TRANSMISSION RISK”.  They reported on a study, highlighted in a BBC report, of possible pathogens imported into the USA via bushmeat from Africa, confiscated at airports.  This in turn derived from a PLoS One paper – “Zoonotic Viruses Associated with Illegally Imported Wildlife Products“, by Kristine Smith et al., published on January 10th 2012.  Their abstract:

The global trade in wildlife has historically contributed to the emergence and spread of infectious diseases. The United States is the world’s largest importer of wildlife and wildlife products, yet minimal pathogen surveillance has precluded assessment of the health risks posed by this practice. This report details the findings of a pilot project to establish surveillance methodology for zoonotic agents in confiscated wildlife products. Initial findings from samples collected at several international airports identified parts originating from nonhuman primate (NHP) and rodent species, including baboon, chimpanzee, mangabey, guenon, green monkey, cane rat and rat. Pathogen screening identified retroviruses (simian foamy virus) and/or herpesviruses (cytomegalovirus and lymphocryptovirus) in the NHP samples. These results are the first demonstration that illegal bushmeat importation into the United States could act as a conduit for pathogen spread, and suggest that implementation of disease surveillance of the wildlife trade will help facilitate prevention of disease emergence.

What was even more horrifying were the pictures of confiscated items – herewith their Figure 1.


It boggles my mind how anyone could even consider smuggling this sort of thing into anywhere – and I am hoping that the US Customs has the same sorts of detection mechanism – as in, well-trained beagles – as they used to have in Miami Airport to detect biltong [dried spiced meat] smuggled in from South Africa.  Those dogs were seriously good – trouble is, they really loved the biltong they got as a reward, too, and it makes my skin crawl rather to imagine a beagle salivating over smoked vervet monkey.

The ProMED post comments further:

No one really knows the scale of the illegal trade in wildlife meat, or bushmeat as it is often called, but a 2010 study estimated that 5 tonnes of the material per week was being smuggled in personal baggage through Roissy-Charles de Gaulle airport in Paris, France. And in addition to the meat products, there is a big trade in live wild animals. Much of this is perfectly legal and supplies the pet industry. Nonetheless, these animals also require improved pathogen surveillance, say the researchers.

One has only to remember that the monkeypox outbreak in the USA in recent times originated in an African animal imported live – see Viroblogy here – to realise the potential danger posed by international movement of wild-caught animals – or even of laboratory animals, as happened in the Ebola Reston incident.

The list of animals from whom parts were found is also rather disturbing: this included chimpanzee, sooty mangabey, and “green monkey” or vervet.  Virologists will not need reminding, but others may, that HIV-1 originated in chimpanzees and HIV-2 in mangabeys – and that although these viruses were not found this time, the PLoS One paper notes:

“Although we did not find SIV or STLV in the limited number of specimens in this study, these viruses have been found in high prevalences in NHP specimens at bushmeat markets and in hunted NHPs [8], [32], [33]. HIV-1 and HIV-2 emerged as a result of several spillover events of SIV from chimpanzees and mangabeys, respectively, that were likely hunted for bushmeat in central and western Africa [30]. Serosurveillance studies have shown thirty-five different species of African NHPs harbor lentivirus infections, with a prevalence of SIV in up to 35% of free-ranging chimpanzees, and 30–60% of free-ranging sooty mangabeys and green monkeys [30], [31], [33], [34].”

So really, it is just a matter of time before meat that contains SIVs or STLVs gets through into the USA and other world centres – and a whole new wave of zoonotic infection could start.  It really is inexcusable that people living in developed countries should be importing meat derived from endangered species in the first place.  It is made worse that developed countries like the USA find it necessary to import LIVE animals as pets – and while the monkeypox outbreak was caught early, the next one may not be.

So forget the “engineered” H5N1 paranoia, folks – be a LOT more scared of the cute rodent in a cage near you, or what your neighbour may be eating….

Integrating the enemy

23 November, 2010

Ever since I first discovered them as a student, sometime in 1976, I have found retroviruses fascinating.  Not quite as fascinating as Ebola, possibly, but captivating nonetheless.  The whole concept of a virus that converts a perfectly ordinary mRNA into dsDNA, then  inserts it into the host chromosome as a provirus in a eukaryotic version of lysogeny – was truly wonderful.

And as the years have gone by, I have seen no reason to lessen the feeling of wonderment: other

The Retroid Virus Replication Cycle

viruses – now called pararetroviruses, including both hepadnaviruses and plant viruses – whose replication  starts at a different position in the  cycle have been found; these and retroviruses have been integrated into a whole family of “reverse transcribing elements” – retrons – which include prokaryote transposons; HIV burst in on the scene, and suddenly we know so much about how the immune system works, because a virus messes with it so well.

But the actual mechanics of one particular process have consistently escaped elucidation – until now.  The 11 November issue of Nature contains, apart from only the second SF short-short story by a South African (kudos, Anand!), a Letter of great interest.

The mechanism of retroviral integration from X-ray structures of its key intermediates
Goedele N. Maertens, Stephen Hare & Peter Cherepanov
Nature 468,326–329 (11 November 2010) doi:10.1038/nature09517

To establish productive infection, a retrovirus must insert a DNA replica of its genome into host cell chromosomal DNA. This process is operated by the intasome, a nucleoprotein complex composed of an integrase tetramer (IN) assembled on the viral DNA ends. The intasome engages chromosomal DNA within a target capture complex to carry out strand transfer, irreversibly joining the viral and cellular DNA molecules. Although several intasome/transpososome structures from the DDE(D) recombinase superfamily have been reported, the mechanics of target DNA capture and strand transfer by these enzymes remained unclear. Here we report crystal structures of the intasome from prototype foamy virus in complex with target DNA, elucidating the pre-integration target DNA capture and post-catalytic strand transfer intermediates of the retroviral integration process. [my emphasis – Ed] The cleft between IN dimers within the intasome accommodates chromosomal DNA in a severely bent conformation, allowing widely spaced IN active sites to access the scissile phosphodiester bonds. Our results resolve the structural basis for retroviral DNA integration and provide a framework for the design of INs with altered target sequences.

Basically, these folk have managed to freeze-frame several different stages of the process in crystals, by clever use of synthetic DNA targets – and then solved the structures.  NOT trivial, and the pictures are absolutely superb.  So are the movies…but you need to subscribe to Nature to see those.

Harking back to a previous post – Entrance, Entertainment and Exit, anyone? –  the more we know about viruses, the more we can mess with them.  And this is a VERY good step along that road.