‘Antibodies from Ebola survivors could provide effective therapies’

• Personal protective equipment may not shield health care workers
• UN envoy lauds Jonathan
SCIENTISTS are making progress in the search for effective treatment and cure for the dreaded Ebola Virus Disease (EVD) with the discovery that antibodies from the eight Nigerians and two United States (U.S.) survivors could be used to provide immunity against the infection in general population.
Researchers reported Wenesday in a new study published in the journal ACS Chemical Biology of a possible therapy that could someday help treat patients infected with one of the most lethal strains of the Sudan Ebola Virus (SUDV).
Wenesday, the Federal Government was commended for its response to the Ebola outbreak. The commendation came from the United Nations Secretary-General Special Envoy on Ebola Virus, Dr. David Navaro, who met President Goodluck Jonathan at the Presidential Villa.
Navaro said: “I have discussed with the President the result of my mission in other countries in the region and we also examined the situation of Ebola Virus Disease in Nigeria. The point I made to the President of Nigeria is that this country and its people have performed excellently in their response to the Ebola Virus Disease.
“It has been a whole of country effort. The whole of the society has been involved and the correct procedures are being adopted. There will always be outbreaks of dangerous diseases in our world because of globalisation, because we want free movement between countries and between communities and because there are viruses that move from the animal kingdom to the human population.
“The good public health techniques and the full involvement of all of society, strong leadership by all, whatever their political party, can lead to successful control effort.
“We of course regret that some people lost their lives. There may be some one who got sick and died as a result of this current Ebola insertion into Nigeria but I am confident that the government and the people are responding in a proper way and to ensure that the situation is kept under control by the way they are paying full attention to the people’s rights and entitlement.”
However, the Minister of Health, Prof. Onyebuchi Chukwu noted that despite the acclaimed successes in containing the spread of Ebola to other parts of the country, a lot still needed to be done to completely eradicate the dreaded disease from the country’s territory.
Studies of blood samples taken from Ebola survivors a few years after they became infected with the virus show that these people have developed antibodies that can neutralise the Ebola virus. This suggests that Ebola survivors are immune to the disease, and will not get infected again.
However, no one has tested what really happens if a survivor is exposed to the virus for a second time. According to the researchers, it is not clear whether survivors become immune to all strains of the Ebola virus or only the one that infected them, nor is it clear how long this immunity lasts.
A commentary published yesterday in Annals of Internal Medicine noted that personal protective equipment designed to shield health care workers from contaminated body fluids of Ebola patients is not enough to prevent transmission.
According to the study, despite the known effectiveness of barrier protection in blocking Ebola transmission, infections among health care workers have played a major role in outbreaks.
According to the World Health Organisation (WHO), there are five known species of the Ebola virus, none of which have approved therapies. The current outbreak is caused by Zaire Ebola virus, which is the deadliest type. In previous outbreaks involving this strain, only 10 per cent of patients have survived the infection.
The team of researchers led by John Dye, Sachdev Sidhu and Jonathan Lai explain that about 50 to 90 per cent of Ebola patients die after experiencing the typical symptoms of the disease, which include fever, muscle aches, vomiting and bleeding.
However, in the current outbreak, according to the WHO, about 47 per cent of people infected with the virus have survived. It is possible that early treatment efforts have played a role in improving survival rates in this outbreak.

Of the five known Ebola viruses, the Zaire (EBOV) and SUDV strains are the most deadly and cause the most recurring outbreaks. Many studies have focused on EBOV, the culprit of the current epidemic, but much less attention has been placed on SUDV until now. To develop a therapy for SUDV, this research team turned to an antibody that Dye’s group previously reported.
The team’s antibody was directed against SUDV and was made in mice. But the human immune system could potentially recognise that antibody as foreign and ultimately get rid of it, preventing the antibody from treating the disease. To avoid this situation, they wanted to make a “humanised” version of the antibody.
In the newly published work, the team put the Ebola-specific part of the mouse antibody onto a human antibody scaffold and made some changes to this molecule. They identified two versions that were able to fend off SUDV in laboratory tests on cells and in specially bred mice. “These antibodies represent strong immunotherapeutic candidates for the treatment of SUDV infection,” say the researchers.
According to the researchers, this study, however, is not expected to help with the current Ebola outbreak that, as of mid-August, has killed at least 1,430 people. That is because antibodies that kill off one strain of the virus have not worked against other strains. The U.S. Food and Drug Administration (FDA), which has not yet approved any Ebola therapies, did allow two U.S. aid workers infected during the current outbreak to be treated with an experimental drug, which is a cocktail of antibodies specifically targeting EBOV.
Experts say the two American Ebola patients who recovered and left the hospital last week are now thought to be immune to the strain of the virus that infected them. Ebola survivors are generally believed to be immune to future infection with the virus strain that made them sick.
The director of the infectious disease unit at Emory University Hospital in Atlanta, Dr. Bruce Ribner, told reporters last Thursday: “There is strong epidemiological evidence that once an individual has resolved an Ebola virus infection, they are immune to that strain.”
Dr. Kent Brantly and Nancy Writebol contracted the Ebola virus while caring for patients in the current Ebola outbreak in West Africa. They received an experimental drug, and were flown to the U.S., where they recovered. Tests showed both patients were free of the Ebola virus after spending three weeks in the hospital.
Ribner said: “Assuming that Brantly and Writebol continue to recover, they would not be at risk of becoming sick again with Ebola if they were to decide to return to Africa. They would probably not be at risk for infection if they were caring for patients with Ebola disease during this outbreak.”
In the current outbreak, about 47 per cent of people infected with the virus have survived, according to the WHO. It is possible that early treatment efforts have played a role in improving survival rates in this outbreak.
It is not clear which biological factors may determine a person’s chance of surviving Ebola, but a stronger immune system appears to be one important factor. Also, laboratory evidence suggests that some people with a genetic mutation may be entirely resistant to Ebola infection.
Ribner says the doctors still do not know if the experimental drug played any role in helping the American Ebola patients survive, but patients’ better nutrition and stronger immune systems may have helped their recovery.
William A. Fischer, from the University of North Carolina at Chapel Hill School of Medicine, U.S., and co-authors wrote that there are two factors contributing to the high rate of Ebola infection among health care workers: insufficient supply of personal protective equipment and lack of emphasis on the process of donning and doffing it.
They wrote: “Ebola is transmitted through direct or indirect contact between bodily fluids from an infected patient and breaks in the skin or exposed mucous membranes of an uninfected person. Even with personal protective gear, a health care worker is at risk for infection if removal of contaminated protective clothing is not done carefully.”
To prevent unwitting transmission from contaminated body fluids on personal protective equipment, the authors suggest a structure and systematic process be strictly followed for gear removal.
The WHO does not know how the man became infected with the Ebola virus, as he was not known to have exposure to Ebola patients — he was a surveillance officer and did not treat patients directly. According to the WHO, more than 240 health care workers have been infected with Ebola since its outbreak.
The Director of WHO communications in West Africa, Christy Feig, told the Associated Press: “The international surge of health workers is extremely important and if something happens, if health workers get infected and it scares off other international health workers from coming, we will be in dire straits.”