The Half Decent Pharmaceutical Chemistry Blog

The British isles must be the worst place to live if you’re a farmer. Especially if trying to live off cattle. A few years ago, cows started to run amok due to a massive outbreak bovine spongiform encephalopathy.

Recently, however, it looked as if that kind of issue belonged to the past and a new, bright era, thanks to efficient and preventive measures, was about to begin. But at this point, global warming (what else?) has broke into the shed, in the shape of a nasty, African midge (Culicoides imicola), which, apparently because of the dramatically altered weather conditions, has now begun to feel at home in Northern Europe too.

This insect is the vector of  the so-called Bluetongue disease, for which there’s neither vaccine nor specific pharmacological treatment. So, people are now wondering whether we are on the verge of a second Mad Cow catastrophe.

Happily, I think we can firmly affirm that, although the authorities must act quickly and efficiently, the situation looks under control, at least now.
Moreover, unlike BSE, this disease doesn’t affect humans and, even when a ruminant gets infected, it isn’t irreversible. The former aspect has to be strongly highlighted because the media might confuse themselves and the people and misinterpret a key point, with awful consequences.
Thing is, the Bluetongue virus (BTV) that triggers catarrhal fever in ruminants belongs to the family of Reoviridae, which features among its member the genus Rotavirus (actually the most famous one), a cause of severe diarrhea in children, and Reovirus, responsible for respiratory tract affections.

Anyhow, BTV is an Orbivirus, which, as previously stated, can’t do any harm to humans.
 
Sure, this new situation is going to have deep economical consequences on the European market, but that’s a different story.

Reoviridae are certainly interesting viruses. Their most impressive feature, in my opinion, is that their genome is a 18 – 30 kbp, segmented (10 – 12 linear segments), double-stranded RNA.
When the virus gets inside a host cell, a virion enzyme (namely a viral transcriptase: an RNA polymerase – RNA dependent) yields a strand of RNA, which serves as mRNA for the synthesis of all the proteins a Reoviridae needs to complete a replication cycle. The capsid of Reoviridae is made of proteins only and, even while infecting a host, these viruses always maintain their inner capsid (keeping, hence, a partially structured virion, which is metabolically active).
First, a partial virion is assembled; then the first, positive strand doubles as template for the synthesis of the complementary, negative strand. Finally the virion is completed.
You might think it sounds illogically complicated and useless, but it isn’t: a cell that detected a double-stranded RNA, in fact, would respond activating interferons and generally begin to protect itself against the virus. So, it’s pretty witty, isn’t it?