A team of researchers from several institutions have received a grant to fund the development of a vaccine for onchocerciasis, the second leading infectious cause of blindness.
The National Institutes of Health (NIH) has awarded a grant to a Baylor College of Medicine-led study team working to research and develop a vaccine for onchocerciasis, or river blindness.
Transmitted by the parasitic worm Onchocerca volvulus through bites from blackflies, river blindness is the world’s second leading infectious cause of blindness. The disease is endemic to 31 countries in sub-Saharan Africa and has also been transmitted in Yemen as well as in parts of Latin America. The blackfly that carries the parasite breeds in the fast-flowing waters of rivers and streams, and once a female adult worm enters a human body, it produces larval worms that travel to the skin and eyes. According to the Centers for Disease Control and Prevention (CDC), an adult O. volvulus worm can live inside a human for up to 15 years, and female worms can produce thousands of larvae each day. While some infected individuals do not experience symptoms, those who do may develop itchy skin rashes, nodules under the skin, vision changes, and eventually blindness.
River blindness is typically treated with the anti-parasite medication ivermectin, and the World Health Organization (WHO) notes that in the absence of a vaccine to prevent these infections, the disease has been largely mitigated or eliminated through insecticide spraying and other methods. From 1974 to 2002, the Onchocerciasis Control Programme in West Africa used insect spraying and ivermectin distribution to relieve 40 million cases of river blindness, prevent blindness in 600,000 individuals, and protect 18 million children from being born into the threat of the disease.
In a sign that a vaccine may soon be in the pipeline, Baylor College of Medicine recently announced that researchers at the college’s National School of Tropical Medicine are part of a team that has received a 5-year, $3.6 million grant from the NIH’s National Institute of Allergies and Infectious diseases (NIAID) to research and develop an onchocerciasis vaccine. The team also includes researchers from the Texas Children’s Hospital’s Center for Vaccine Development, New York Blood Center, University of Liverpool, and Thomas Jefferson University.
The project helps to continue the work that began in 2015 with The Onchocerciasis Vaccine for Africa (TOVA), an international initiative to eliminate river blindness through the development of recombinant protein-based vaccines. Maria Elena Bottazzi, PhD, who is leading Baylor’s effort, told Contagion® that funding from the NIH/NIAID grant will be critical in getting the TOVA initiative to its next stages. “One of the biggest roadblocks has been the absence of funds to advance onchocerciasis vaccine development,” said Dr. Bottazzi. “Another [roadblock] is the perception that onchocerciasis might be eliminated with mass drug administration, or MDA, alone. While we agree that MDA has been an important advance in the fight to combat river blindness, evidence shows that it will not be possible to eliminate this disease through MDA alone. [Instead, it] requires innovative complementary tools such as vaccines.”
After applying state-of-the-art practices in vaccine development, the research team is ready for the next stage of the process. “We now have 2 lead vaccine candidates for the river blindness vaccine,” said Dr. Bottazzi. These are the Ov-103 and Ov-RAL-2 antigens the team will be working with. Dr Bottazzi further explained that the vaccine candidates will be evaluated both separately and together when co-administered as a bivalent vaccine. At least 2 sets of clinical trials are on the critical path for TOVA, including Phase 1 clinical trials in adult volunteers for safety and immunogenicity, says Dr. Bottazzi. “Before this is achieved, our funding will be used to support product development activities to develop the vaccine product and perform important preclinical studies to assess immunogenicity and efficacy in a cow model for onchocerciasis.”
Dr. Bottazzi notes that while vaccine development has inherent risks and longtime horizons, this grant brings the world closer to a river blindness vaccine. “Hopefully by the end of the grant period we can advance the vaccine candidates and be ready to commence clinical trials.”