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[stem-ebola] Ebola-2014 May Have Altered Phenotype -- Anecdotal Reports of Higher Viral Loads (NIAID)

Hello everyone,

I am writing to our scientific discussion community to share new evidence that just came to my attention: Some of the Ebola genetic variants circulating in Liberia may result in *higher serum viral titers* than previously observed for species Zaire ebolavirus.

Note: I am using the term 'Ebola-2014' to refer to all Zaire ebolavirus variants circulating during the West African outbreak of 2014. All variants sequenced so far in the outbreak share approximately 97% homology with the Mayinga-76 consensus sequence, and have fall into approximately four phylogenetic sub-clades (GN, SL1, SL2, and SL3) (Gire et al, 2014).

We have all been asking the question of 'What's different this time?' regarding the outbreak since our first community call.

During last weeks discussion , we discussed the fact that Ebola-2014 genetic variants had already acquired significant genetic diversity from Feb 2014 to June 2014. However, as of last week, there had been no evidence that Ebola-2014 mutations had impacted the viral phenotype.

That may have changed. We will need to await formal confirmation and write up of the following findings, but the following anecdotal reports could end up to be very important.


To quote Dr. Jahrling at NIH/NIAID, "If [what we observe is] true, [Ebola 2014] is a very different bug."

Case reports have just come to light suggesting that Ebola-2014, particularly the genetic variants circulating in Liberia, have been resulting in significantly _higher serum viral titers_ as compared to previous outbreaks of Zaire ebolavirus.

The reports come from the field lab of Dr. Peter Jahrling (Chief Scientist, Emerging Viral Pathogens, NIH/NIAID), who has a team on the ground in Monrovia, Liberia.

According to WHO reports distributed on ProMED, Monrovia is one of the key areas where the Ebola outbreak is growing rapidly.


Dr. Jahrling stated the following in a recent interview...

'We are using tests now that weren't using in the past, but there seems to be a belief that the [Ebola] virus load is higher in these patients [today] than what we have seen before. If true, that's a very different bug.'

'I have a field team in Monrovia. They are running [tests]. They are telling me that viral loads are coming up very quickly and really high, higher than they are used to seeing.'

'It may be that the virus burns hotter and quicker.' -Dr. Peter Jahrling, Oct 13th, 2014


Dr. Jahrling is highly credible. He was a co-discover of the Reston ebolavirus species.

If confirmed, his team's observation could have a number of interpretations and implications. For example, we know there are an increasing number of distinct Ebola-2014 viral lineages, which are growing as a function of the number of people infected (Gire, 2014).

Some of the Ebola-2014 genetic variants found in current outbreak may be responsible for changes in EVD etiology, such as the increased viral shedding claimed by Dr. Jahrling.

The anecdotal reports from Dr. Jahrling's field lab are the first credible claims that Ebola-2014 genetic changes are having an observable phenotypic impact on EVD. If Dr. Jahrling's anecdotal field observations hold up to scientific scrutiny, it may imply that Ebola-2014 has acquired at least one fitness adaptation which allows it to replicate and amplify to higher viral loads.

If this discovery is true and not an error, then the fact that one or more Ebola-2014 genetic variants are resulting in an altered phenotype might be evidence for a new Ebola 'strain' (Kuhn, 2012) within the species Zaire ebolavirus.

The ability for an Ebola-2014 genetic variant to achieve higher viral loads could potentially make the virus more contagious (increasing R0). . . Higher viral titers could increase overall viral shedding. On a more speculative note, higher viral titers might alter ratios of circulating Ebola PFU/mL relative to levels of circulating cytokines like IL-6, perhaps providing a theoretical basis for 'asymptomatic transmission'.

From Vox Interview Article...

Peter Jahrling, one of the country's top scientists, has dedicated his life to studying some of the most dangerous viruses on the planet. Twenty-five years ago, he cut his teeth on Lassa hemorrhagic fever, hunting for Ebola's viral cousin in Liberia. In 1989, he helped discover Reston, a new Ebola strain, in his Virginia lab.

Jahrling now serves as a chief scientist at the National Institute of Allergy and Infectious Diseases, where he runs the emerging viral pathogens section. He has been watching this Ebola epidemic with a mixture of horror, concern and scientific curiosity. And there's one thing he's found particularly worrisome: the mutations of the virus that are circulating now look to be more contagious than the ones that have turned up in the past.

When his team has run tests on patients in Liberia, they seem to carry a much higher "viral load." In other words, Ebola victims today have more of the virus in their blood — and that could make them more contagious.


The anecdotal reports from Dr. Jahrling's team will need to be confirmed by follow-up research.

I wanted to make everyone aware of this development as perhaps something to follow up on in the future, perhaps as a subject for expert evaluation by others.

Genetic changes to the virus could prove problematic (given the high mutation rate), and will need to be monitored closely.




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