This is an update of an earlier post, Know Your Species: SUDV vs EBOV.
When last we discussed the Democratic Republic of Congo outbreak of Ebola, it was presumed that it was actually an outbreak of the genus Ebolavirus, species Sudan ebolavirus (SUDV), largely because that’s what initial reports indicated. It hasn’t yet been clarified why there were reports of a positive test for SUDV and a positive test for a SUDV/EBOV mix (although I’ve heard speculations about earlier outbreak exposure), but what we do know is that on 2 September, the World Health Organization released the results from their virological analysis, showing that while the Ebola outbreak in the DRC was actually EBOV (Zaire ebolavirus),
This brings us back to my last post illustrating Ebola with kittehs.
And then we have a obligatory illustrative cute cat picture, because this is just like
But what does it mean when we learn that, in fact, it’s the same species of ebolavirus, but different variant? Simply put, it just means being even more specific: variant fits inside species fits inside genus fits inside family.
Variants are written out in a specific way that tells you the virus name, the isolation host-suffix, country of sampling, year of sampling, variant designation, and isolate designation. It looks like this:
Ebola virus H.sapiens-tc/COD/1995/Kikwit-9510621
The current epidemic started with, it is presumed, a Guinea variant GuÃ©ckÃ©dou,
Ebola virus H.sapiens-wt/GIN/2014/Gueckedou-XXXXX
This tells us that it’s an ebolavirus infecting homo sapiens (that’s us humans), wild type (it hasn’t been cultured), that it was sampled in Guinea in 2014, and that the variant is GuÃ©ckÃ©dou.
Clearly, at this point, it becomes harder to do a one-to-one correlation between viruses and kitties, because kitties don’t break down into variants and isolates, but work with me a bit here. What cats do break down into is year they were born, litter, and even what they look like. So we do have ways we tell each individual Felis catus apart, even though we recognize them all as belonging to the genus Felis and species catus.
In theory, we could roughly write these two cats out like this, utilizing their species, country of origin, year they were born, where they were born, and their name:
Just as we can all look at Zeus and Toledo and see that they’re different domestic cats (but still clearly domestic cats, all the same), researchers can look at the virus they isolate from individuals and see that they’re different variants of the same strain. In the case of the outbreak in the DRC, it was a variant most closely related to the 1995 Kikwit Zaire ebolavirus outbreak.
So why does this matter? In an era of ebolanoia, it’s important to understand what it means when there’s an epidemic of Ebola in one area of the world and a new outbreak in another. People are quick to panic and assume that all outbreaks are connected to the epidemic, and equally quick to forget that ebolavirus has been cropping up sporadically for nearly 40 years in other parts of Africa. Knowing how scientists differentiate between strains and variants within viruses is another tool in being an educated and informed media consumer.