Dancing Bundibugio: Russian Ebola vaccine protects against "incurable" strain

The Russian vaccine against the Ebola virus is capable of forming immunity against the Bundibugio strain that is currently spreading in Africa, Alexander Ginzburg, scientific director of the Gamalei Center, told Izvestia. According to experts, there are currently no specific means of protection against this variant of the pathogen, and the strain itself is considered extremely dangerous. WHO reports at least 500 cases of infection and 130 deaths in the DRC and Rwanda. Rospotrebnadzor is sending specialists to help African countries. At the same time, virologists assess the risk of infection spreading to other continents as low: transmission requires close contact with the patient, and for sustained spread through animals, the pathogen must overcome the interspecific barrier several times, which is unlikely.

The Ebola virus vaccine

The existing Russian Ebola virus vaccine, created at the N.F. Gamalei Research Center for Epidemiology and Microbiology, should also protect against the rare Bundibugyo ebolavirus strain currently spreading in Africa, Alexander Gintsburg, the scientific director of the center, told Izvestia.

— Degree of homology (genetic similarity — Izvestia) this vaccine strain reaches 60-70%, so doctors who work there need to be protected not with masks, but with an existing drug. I believe that it can give immunity from this pathogen, although we have not tested this. In the absence of other means, we need to use this," he said.

At the same time, it is necessary to create a separate vaccine against the Bundibugio strain, but there is no sample of this pathogen at the institute, the specialist added.

On May 17, WHO recognized the outbreak of Ebola in the Democratic Republic of the Congo and Uganda as a "public health emergency of international importance." According to the organization, the situation is complicated by the fact that not the most common Ebola strain, Zaire, is widespread, but a rarer variant, Bundibugio, for which there are no approved medicines or vaccines yet.

WHO Director-General Tedros Adhanom Ghebreyesus said that the situation has already led to more than 500 possible cases of the disease and approximately 130 deaths. At the same time, 32 cases of infection have been confirmed (30 in the DRC and two in Uganda), with both Ugandan infected arriving in the country from the DRC.

Modeling by the British Council for Medical Research shows that the actual number of infected people may exceed 1,000 cases, as part of the transmission chain could remain undetected. WHO recommends isolating patients and monitoring all their contacts, limiting travel within and outside countries, and observing a 21-day quarantine after contact with an infected person. To combat the spread of infection, the international organization considers it necessary to create a network of special centers.

Rospotrebnadzor said it would send a team of specialists to Uganda to conduct an epidemiological investigation. Russia will also provide logistical assistance to the Ministry of Health of the Republic and will transfer tests developed by subordinate scientific organizations and used in our country to diagnose fever.

From "Puumala" to velika: "Russian" hantaviruses may become more dangerous

The properties of the pathogen can be easily changed in the laboratory

A rare strain

The peculiarity of the current outbreak is that it is not about the classic Ebola virus (Zaire ebolavirus), against which vaccines already exist, including those developed by the Gamalea Center, but about a rarer variant — Bundibugyo ebolavirus. To date, there is no licensed vaccine or specific therapy for it, which complicates anti-epidemic measures: existing vaccine platforms and diagnostic tests are mainly focused on other types of ebolaviruses, Albert Rizvanov, head of the Personalized Medicine Center of Excellence at Kazan (Volga Region) Federal University, explained to Izvestia. In addition, the outbreak is developing in a region with high population migration and limited access to medical care, making it difficult to control the spread of infection.

— The probability of widespread spread of the virus in Russia is estimated as low. Transmission of ebolaviruses requires close enough contact with the body fluids of a sick person. This is not a virus that is easily spread by airborne droplets, like the flu or coronavirus. The main risk for any country is associated not so much with isolated imported cases, as with the possibility of forming a natural reservoir among animals," said the doctor.

For ebolaviruses, some species of bats are considered to be the main natural hosts, distributed mainly in tropical regions of Africa. There is no evidence yet that there are suitable natural reservoirs in Russia that can support the circulation of this particular variant of the virus, so the risk of infection becoming entrenched in the nature of our country seems limited, the expert added.

Testing of ebolavirus vaccines usually follows an accelerated schedule due to their high mortality rate of infection. First, immunogenicity and safety are evaluated in animal models, including primates, followed by clinical trials in volunteers. During outbreaks, the tactic of "ring vaccination" is additionally used — when people who have come into contact with the patient, as well as their immediate environment, are vaccinated in order to localize the spread of infection.

"However, the problem for Bundibugyo ebolavirus is that there are no ready—made registered platforms yet, so now we are talking either about adapting existing Ebola virus vaccines or developing new mRNA and vector preparations that have shown their effectiveness during the coronavirus pandemic," said Albert Rizvanov.

Immunologist Mikhail Bolkov agrees with the opinion that the Ebola virus is unlikely to spread beyond Africa with the help of wild animals. He explains this by the fact that the pathogen must repeatedly overcome the interspecific barrier, which is extremely rare. However, according to him, there are cases of prolonged persistence of the virus in the body of those who have been ill, including in the reproductive organs of recovered patients, which theoretically allows for the possibility of sexual transmission long after the outbreak.

As noted by Andrey Pozdnyakov, an infectious disease specialist at INVITRO, Bundibugio is a common strain of Ebola, the key problem of which is the lack of a specific vaccine. However, he stressed that the virus has not become more contagious and has not acquired new transmission mechanisms. According to him, the probability of an outbreak in Russia is extremely low and almost zero.