I have to thank my long-time digital media guru, Alan J Cann, for reviewing our humble eBook offerings in MicrobiologyBytes. You good man! Much appreciated, and it will not have escaped our attention that this endorsement may actually result in sales. If so, a glass or three of the finest red is yours if you come to these shores, good sir B-)
Archive for the ‘Ebola’ Category
The discovery of filoviruses: Marburg and Ebola
In 1967, the world was introduced to a new virus: thirty-one people in Marburg and Frankfurt in Germany, and Belgrade in the then Yugoslavia, became infected in a linked outbreak with a novel haemorrhagic fever agent. Twenty-five of them were laboratory workers associated with research centres, and were directly infected via contact with infected vervet monkeys (Chlorocebus aethiops) imported to all three centres from Uganda. Seven people died. In what what was a remarkably short period of time for that era – given that this was pre-sequencing and cloning of nucleic acids, let alone viruses – it took less than three months for scientists from Marburg and Hamburg to isolate and characterise what was being called “green monkey virus” virus. The new agent was named Marburg virus (MARV), after the city with the greatest number of cases.
The first electron micrograph of the virus clearly exhibits the filamentous nature of the particles, complete with the now-famous “shepherd’s crook”.
The virus disappeared until 1975, when an Australian hitchhiker who had travelled through what is now Zimbabwe was hospitalised in Johannesburg, South Africa, with symptoms reminiscent of Marburg disease. He died, and his female companion and then a nurse also became infected with what was suspected to be yellow fever or Lassa viruses. In an example for later outbreaks, this led to rapid implementation of strict barrier nursing and isolation of the patients and their contacts, which resulted in quick containment of the outbreak – with recovery of the two secondary cases. MARV was later identified in all three patients.
Ebola viruses burst from obscurity in 1976, with two spectacular outbreaks of severe haemorrhagic fever in people – both in Africa. In the better-known outbreak for which the viruses were later named, Ebola virus (EBOV) was first associated with an outbreak that eventually totalled 318 cases, starting in September 1976. This was in the Bumba Zone of the Equateur Region in the north of what was then Zaire, and is now the Democratic Republic of the Congo (DRC). The index case in the outbreak, as well as many of those subsequently infected, was treated in the Yambuku Mission Hospital. He was injected with chloroquine to treat his presumptive malaria: within a few days fever symptoms developed again; within a week, several others who had received injections around the same time also developed fevers which in several cases had haemorrhagic complications.
Interestingly, women 15-29 years of age were most affected by the disease: this was strongly correlated with their attending antenatal clinics at the hospital, where they regularly received injections.
Apparently the hospital had only five old-style syringes and needles, and these were reused without proper sterilisation. Nearly all cases in this outbreak either received injections at the hospital, or had close contact with those who had.
Most people were infected within the first four weeks of the outbreak, after which the hospital was closed because 11 of 17 staff had died. Another 269 people died, for a total estimated case-fatality rate of 88%.
The incubation period for needle- transmitted Ebola virus was 5 to 7 days and that for person to person transmitted disease was 6 to 12 days.
Interestingly, in post-epidemic serosurveys in DRC, antibody prevalence to the “Zaire Ebola virus” has been 3 to 7%: this indicates that subclinical infections with the disease agent may well be reasonably common.
The team that discovered the virus at the Antwerp Institute of Tropical Medicine in Belgium, did so after receiving blood samples in September 1976 from a sick Belgian nun with haemorrhagic symptoms who had been evacuated from Yambuku to Kinshasa in the DRC, for them to investigate a possible diagnosis of yellow fever. Following her death, liver biopsy samples were also shipped to Antwerp – where the team had already ruled out yellow fever and Lassa fever. Because of the severe nature of the disease, and its apparently novel agent, the World Health Organisation (WHO) arranged that samples be sent to other reference centres for haemorrhagic viruses, including the Centres for Disease Control (CDC) in Atlanta, USA.
The Belgian team were the first to image the virus derived from cell cultures on an electron microscope – when it was obvious that the only thing it resembled was Marburg virus.
The CDC quickly confirmed that it was Marburg-like, with possibly the most famous virus image in the world, but that it was a distinct and new virus.
This meant it needed a name – and it was given one derived from the Ebola River that was supposed to be near the town of Yambuku.
Another, minor outbreak of the virus occurred in June 1997 in Tandala in north-western DRC: one young child died, and virus was recovered from her – and subsequent investigations showed that “two previous clinical infections with Ebola virus had occurred in 1972 and that about 7% of the residents had immunofluorescent antibodies to the virus”. This further reinforced the idea that subclinical infections were possible.
In June 1976 – before the Yambuku epidemic in DRC – an outbreak of a haemorrhagic fever began in the southern Sudanese town of Nzara. The presumed index case was a storekeeper in a cotton factory, who was hospitalised on June 30th, and died within a week.
There were a total of 284 cases in this outbreak: there were 67 in Nzara, where it is presumed to have originated, and where infection spread from factory workers to their familes. There were also 213 in Maridi, a few hours drive away – where, as in Yambuku, the outbreak was amplified by “nosocomial” or hospital-acquired transmission in a large hospital. In this case, transmission seems to have been associated with nursing of patients. The incubation period in this outbreak was 7 – 14 days, with a case mortality rate of 53%.
Two viral isolates were made from sera from Maridi hospital patients in November 1976. Antibodies to the now-identified “Ebola virus” from DRC were detected in 42 of 48 patients clinically-diagnosed patients from Maridi – but in only 6 of 31 patients from Nzara. However, it was subsequently shown that the Sudan and DRC Ebola viruses were different enough from one another to be separate viral species (see later), which undoubtedly affected the results.
Interestingly, 19% of the Maridi case contacts had antibodies to the virus – with very few of them with any history of illness. This strongly indicates that the Sudan virus can cause mild or even subclinical infections.
An indication of the possible origin of the epidemic is the fact that 37% of the workers in the Nzara cotton factory appeared to have been infected, with 6 independently-acquired infections – and that this was concentrated in the cloth room, where there were numerous rats as well as thousands of insectivorous bats in the roof. However, subsequent study of antibodies in the bats failed to detect evidence of infection, and no virus was isolated from bat tissue.
There was another outbreak of the same type of Ebola haemorrhagic fever in the area of Nzara in July – October 1979: this resulted in 34 cases, 22 of them fatal, with the index patient working at the cotton factory and all others being infected via the hospital he was admitted to. It is interesting that antibodies to the Sudan virus were detected in 18% of adults not associated with the outbreak, leading the report’s authors to speculate that the virus was endemic in this region.
It was thought that the Sudan and DRC outbreaks were linked: the original WHO Bulletin report on the Sudan outbreak even speculates that extensive truck-borne commercial goods traffic between Bumba in DRC and Nzara in what is now South Sudan could have caused the DRC outbreak. However, comparisons between the viruses isolated from the two epidemics later showed that they were distinct, both in terms of virulence, and antigenicity – meaning the Sudan virus got its own name.
Epidemics and outbreaks have resulted from person to person transmission, nosocomial or in-hospital spread, or laboratory infections. The mode of primary infection and the natural ecology of these viruses are unknown. Association with bats has been implicated directly in at least 2 episodes when individuals entered the same bat-filled cave in Eastern Kenya. Ebola infections in Sudan in 1976 and 1979 occurred in workers of a cotton factory containing thousands of bats in the roof. However, in all early instances, study of antibody in bats failed to detect evidence of infection, and no virus was isolated form bat tissue.
Scientists at the Institut Pasteur in France who are tracking the Ebola outbreak in Guinea say the virus has mutated.
I would be surprised it there weren’t evidence by now of adaptation to humans: never in any previous outbreak of EHD [Ebola haemorrhagic disease] has the person-person chain of transmission been sustained for so long, meaning never before has there been the opportunity for human-specific adaptations to become established.
The article points out that on consequence of mutation may be that the virus becomes less virulent, leading to a greater incidence of asymptomatic infection – of which there is already evidence from previous outbreaks, and which has been implicated in the lessening incidence of transmission because of increasing herd immunity.
However, this same property might lead to increased transmission to the non-exposed, because of a lack of signs that contacts with the infected person(s) should be avoided – and for a disease as lethal as EHD, even a reduced mortality rate still means you should avoid it at all costs.
The idea of developing a modified live measles virus vaccine as an Ebola virus vaccine vector, which is what the Institut Pasteur is apparently doing, seems to be a very good one. Measles is still a major potential problem in that part of the world, necessitating regular infant immunisations, and coupling anti-measles with an anti-Ebola vaccine in those countries is probably very good use of both a proven vaccine and existing EPI infrastructure.
Public-health officials split on use of control groups in tests of experimental treatments.
With clinical trials of experimental Ebola treatments set to begin in December, public-health officials face a major ethical quandary: should some participants be placed in a control group that receives only standard symptomatic treatment, despite a mortality rate of around 70% for Ebola in West Africa?
Two groups planning trials in Guinea and Liberia are diverging on this point, and key decisions for both are likely to come this week. US researchers meet on 11 November at the National Institutes of Health (NIH) in Bethesda, Maryland, to discuss US-government sponsored trials. A separate group is gathering at the World Health Organization (WHO) in Geneva, Switzerland, on 11 and 12 November to confer on both the US effort and trials organized by the WHO with help from African and European researchers and funded by the Wellcome Trust and the European Union.
I have to say – faced with a deadly disease, I think it is UNethical to have control / placebo arms of any trial.
Seriously: what about comparing ZMapp and immune serum, for example, with historical records of previous standard of care outcomes rather than directly?
I know if I were an Ebola patient, and I saw someone else getting the experimental therapy and I didn’t, that I would have a few things to say.
It’s not as if these therapies have not been tested in primates, after all – in fact, both the ChAd3 and MVA-based vaccines and ZMapp have been thoroughly tested in macaques, as have the other therapeutics, with no adverse events there.
I say if people say clearly that they want an experimental intervention, that they should get one: after all, the first use of immune serum was not done in a clinical trial, but rather as a last-ditch let’s-see-if-this-works intervention – yet its use does not seem controversial?
Dear ViroBlogy and Virology News followers:
Anna-Lise Williamson and I plan to have another in our irregular series of “Virology Africa” conferences in November-December 2015, in Cape Town.
As previously, the conference will run over 3 days or so, possibly with associated workshops, and while the venue is not decided, we would like to base it at least partially in the Victoria & Alfred Waterfront.
We also intend to cover the whole spectrum of virology, from human through animal to plant; clinical aspects and biotechnology.
We intend to make it as cheap as possible so that students can come. We will also not be inviting a slate of international speakers, as we have found that we always get quite an impressive slate without having to fund them fully.
It is also the intention to have a Plant Molecular Farming workshop – concentrating on plant-made vaccines – concurrently with the conference, in order to leverage existing bilateral travel grants with international partners. If anyone else has such grants that could be similarly leveraged, it would be greatly appreciated.
See you in Cape Town in 2015!
Ed + Anna-Lise
It was truly a pleasure to run into Kevin Whaley of Mapp BioPharmaceutical today, here at the HIVR4P inernational conferrence in Cape Town – so I made him come and have coffee with me and Anna-Lise, so we could chat about molecular farming.
Of course, it is the ZMapp plant-made therapeutic antibody that has set the molecular farming world alight, that was the main topic. Apparently Mapp is looking at a January 2015 date for a clinical trial in the affected West African countries, alongside the adenovirus and RSV-vectored vaccines. The plants for the production of the thousands of doses that will be needed – and recall, that’s a couple of grams per dose at 50 mg/kg – are already growing at Kentucky Bioprocessing in Louisville, so one imagines that a pile of work will be coming their way in the near future.
It’s also sobering to realise that even though plants ARE a more scalable and POTENTIALLY cheaper means of production of biologics, that therapeutic antibody production in particular, MAY be better suited right now to conventional technologies, such as CHO cell or even fungal production.
This is because large quantities of MAbs will be needed, and there is established capacity for production of hundreds of thousands of litres of cell culture right now, and yields and production costs have been driven right down to US$10 / gram for MAbs already, according to Kevin.
This partly answers a question I had during the HIVR4P sessions: if one is to use 20-50 mg/kg dosages for anti-HIV neutralising MAbs such as VRC01, how would it be remotely possible to make the amounts required for use in a developing country setting, where the patient can almost definitely NOT pay?
I still think there is a role for plants – but maybe this will be in the area of prophylactic use of MAbs, where much lower doses may be effective because there is not nearly as much virus to neutralise or inactivate.
And of course, Mapp is involved here too, with plant-made VRC01 in particular being incorporated into microbicides.
A great bunch of people, with really noble aims.
The research team is pursuing the inactivated rabies/Ebola vaccine for use in humans. The live vaccine is being developed for use in protecting wildlife at risk of Ebola virus infection in Africa, which could also serve to prevent transmission into the human population.
I missed this one at the time – and it is an interesting piece of news. Basically, the research team cloned the Ebola envelope glycoprotein GP1 into the extant rabies virus vaccine strain genome, and tested a live version, a replication-deficient version, and a killed whole virion version in macaques.
Their results are interesting enough – 100% protection against challenge for live, 50% for the other two – that they plan to follow up to see whether or not additional doses could improve protection in the two non-replicating versions, and to make a “multivalent filovirus vaccine”.
This can only be welcome news against the backdrop of the still-ongoing epidemic in West Africa – where two other vaccines (recombinant vesicular stomatitis and chimpanzee adenovirus) are probably going to be trialled next year. The rabies version at least is based on a very well characterised vaccine that already protects against an extremely deadly disease – it remains to be seen how well the other two do.
I forgot to mention that I found reference to this article on “The Zombie Research Society”‘s blog site: http://zombieresearchsociety.com/archives/25562. A very apt place if one considers the parallels that are already being drawn between Ebola and a “zombie virus”.
And because I like zombies B-)
Packs of wild dogs spread Ebola after eating corpses
The ever-evolving Ebola narrative is broaching into ludicrous territory, with reports now claiming that wild dogs are going around digging up the rotting remains of deceased victims and eating their flesh in the streets. Special Ebola graveyards, where the dead are being buried in haste and at shallow depths, are reportedly feasting grounds for these dogs, which officials say are capable of spreading the disease to humans.
The Daily Mail says Liberian villagers first came across the dogs while going about their daily routines. Right in the middle of busy streets, they said, hungry hounds were allegedly seen ripping through rotting corpses, to the shock of onlookers. After determining the source of the bodies, it was revealed that shallow graves were to blame.
Stephen Korsman of the Division of Medical Virology at UCT just alerted me to this article, in some distress because they had misquoted him and used his comments out of context. This is a rather wild, sensationalist and highly inaccurate piece from a fringe web site that seems to have blocked me from commenting, because of previous criticism. So, I’ll just do it here.
They comment: "Logically speaking, it makes little sense that asymptomatic dogs are possible Ebola carriers while asymptomatic humans are not. There exists no credible science to substantiate this apparent inconsistency beyond the baseless claims made by government health officials."
Utter garbage: bats carry Nipah virus, SARS-CoV, Ebola, Marburg AND rabies essentially asymptomatically – and can transmit ALL of them to other mammals. So too can deer mice transmit Sin Nombre hantavirus in the south-western USA without showing symptoms. Rodents transmit Lassa fever virus in West Africa every year, again without being symptomatic. Mice can transmit various South American haemorrhagic fever viruses without obviously being sick. I wish they would get their facts straight: this is is very easily checked!
The Norwegian woman, infected by the Ebola in Sierra Leone and currently receiving treatment in Oslo, will get the last dose of the virus treatment medicine ZMapp
…and yet again, the emphasis is on how slow it is to make it – when the whole point of biofarming and transient expression is that it is supposed to be QUICK to make things, and easy to scale up production!!
What is the problem here? KBP has facilities – or says it does – for large-scale production of proteins via transient expression in N benthamiana via rTMV or even BeYDV-based vectors. SO why has it been so difficult to make more ZMapp??
Why, in fact, are we told via other reports that the US government is considering getting Caliber to make it, or even to make the cocktail in CHO cells, because of capacity, when KBP has the equipment?
It can’t be supply of plants, surely: if they’d planted out a big greenhouse or two of N benth the moment ZMapp hit the news, they’d have enough to make many grams of ZMapp right now – given that it takes just a few days of incubation post-infiltraiton to make the protein.
Surely it’s not a protein purification thing – because THAT’S pretty quick too, once the plants have been mushed.
So what IS the bottleneck? cGMP requirement? Lack of certified protocols / equipment? Can someone tell us?? Otherwise, a posterchild for biofarming will end up being made by good old stainless steel cell culture technology, and our favourite way of doing things will have been found to be wanting.
NOTE ADDED 10th October:
Never let it be said I was unwilling to get schooled by a former colleague…Kenneth Palmer just told me what the problem is:
“You may not be aware that the human dose of Zmapp is 12 grams per patient, 3 infusions of 4 grams each. Check the dose in recent Nature paper. If yield of one antibody is 100 mg per kg and you have to produce three antibodies for Zmapp… If you do the arithmetic you will see why the process is “slow””.
So…. Doing just that, you end up with 30 kg N benthamiana per gm of ZMapp as a best-case yield – meaning 360 kg PER PATIENT.
That’s a LOT of N benth – and tooling up for that sort of plant production takes time. Thanks, Kenneth!
I would be VERY interested in a cost breakdown of ZMapp vs CHO cell-produced MAbs – because producing at that sort of scale MUST be prohibitively expensive in stainless steel?
Public health officials knew Ebola was coming. They know how to defeat it. But they’re blowing it anyway.
ld, you still just don’t get it. The Ebola epidemic that is raging across West Africa, killing more than half its victims, will not be conquered with principles of global solidarity and earnest appeals. It will not be stopped with dribbling funds, dozens of volunteer health workers, and barriers across national borders. And the current laboratory-confirmed tolls (3,944 cases, with 2,097 deaths) will soon rise exponentially.
To understand the scale of response the world must mount in order to stop Ebola’s march across Africa (and perhaps other continents), the world community needs to immediately consider the humanitarian efforts following the 2004 tsunami and its devastation of Aceh, Indonesia. The U.S. and Singaporean militaries launched their largest rescue missions in history: The United States alone put 12,600 military personnel to a rescue and recovery mission, including the deployment of nearly the entire Pacific fleet, 48 helicopters, and every Navy hospital ship in the region. The World Bank estimated that some $5 billion in direct aid was poured into the countries hard hit by the tsunami, and millions more were raised from private donors all over the world. And when the dust settled and reconstruction commenced, the affected countries still cried out for more.
A seriously hard-hitting article by a very good journalist with a particular interest in infectious diseases.
And she’s right: Ebola was stopped, not once, but a number of times, as long as 38 years ago, in settings that are as or even more desperate in terms of poverty and lack of medics and medical resources.
The problem is, intervention did not occur soon enough this time, or on a scale sufficient to stem the increase in infections that inevitably followed introduction of the disease into urban settings.
It is a matter of amazement to me, that with the ever-present threat of pandemic influenza AND the recent emergence of MERS, that the WHO should have its "…miniscule epidemic-response department slashed to smithereens by three years of budget cuts".
Seriously: faced with diseases that can jump out of camels, or bats, or rats literally anywhere, WHO has to have budget cuts??