Rio de Janeiro, July 30, GNA – Scientists are advancing multiple vaccine candidates against the Sudan strain of the Ebola virus, raising prospects for improved outbreak preparedness in Africa.
The Sudan virus, first identified in 1976 in Nzara, now South Sudan, causes severe viral haemorrhagic fever and currently has no approved vaccine or specific antiviral treatment.
Dr Vincent Muturi-Kioi, HIV Vaccines Product Development Team Lead and Medical Director at the International AIDS Vaccine Initiative (IAVI) in Kenya, said this during a presentation on vaccine development at the 26th International AIDS Conference in Rio de Janeiro, Brazil .
He said several vaccine platforms targeting the Sudan strain were progressing simultaneously, describing the pace of development as one of the fastest witnessed for an emerging infectious disease.
“The urgency with the development of this vaccine reflects the growing concern over the increasing frequency of Ebola outbreaks and the need for vaccines that can be rapidly deployed before epidemics spiral out of control,” he said.
Dr Muturi-Kioi said one of the leading vaccine candidates was a chimpanzee adenovirus-vectored vaccine developed by the University of Oxford, which was being evaluated as both a single-dose and two-dose regimen.
He said another candidate, developed by Moderna using messenger RNA (mRNA) technology, was expected to enter human clinical trials soon.
Dr Muturi-Kioi said scientists were also developing vaccines using the Vesicular Stomatitis Virus (VSV) platform, the same technology behind the Ebola vaccine deployed during outbreaks in West Africa and the Democratic Republic of Congo.
He said pre-clinical studies of one VSV-based vaccine demonstrated complete protection in non-human primates, even when animals were vaccinated only three days before exposure to the virus.
The findings, he said, suggested the vaccine could be highly effective for “ring vaccination”, a strategy in which close contacts of infected individuals are rapidly immunised to interrupt transmission.
“The ring vaccination approach proved highly successful during the 2014-2016 West African Ebola epidemic, when vaccination of contacts within seven to 10 days after identifying an infected person provided near-complete protection and helped contain the outbreak,” he said.
Dr Muturi-Kioi said the VSV platform offered several advantages, including rapid immune protection, long-lasting immunity, established safety data from more than 500,000 vaccinated individuals, and the capacity for rapid vaccine production during public health emergencies.
He explained that the platform worked by replacing a single gene in the virus vector with the glycoprotein of the target Ebola species, enabling the immune system to recognise and mount a strong defence against the virus without causing disease.
Dr Muturi-Kioi said additional animal studies had demonstrated that vaccination 29 days before exposure resulted in 100 per cent protection against disease, while vaccination three days before exposure also protected all vaccinated animals.
“In one study, animals that received a Sudan virus vaccine followed by a Zaire Ebola vaccine two weeks later achieved complete protection against infection, suggesting that sequential vaccination strategies could eventually provide broader immunity against multiple Ebola species,” he said.
Dr Muturi-Kioi said researchers were also investigating whether existing Ebola vaccines could provide partial cross-protection against newly emerging strains while species-specific vaccines remained under development.
He said the work was being undertaken in collaboration with the Africa Centres for Disease Control and Prevention (Africa CDC), public health agencies and vaccine developers to help protect healthcare workers and vulnerable populations during outbreaks.
GNA
Edited by Kenneth Sackey
Reporter: Linda Naa Deide Aryeetey.
Email: [email protected]