A fungal-based vaccine could be used as a cost-effective, Africa-made strategy to prevent human papillomavirus (HPV), which causes almost all cervical cancers.

The C1 platform, led by Dr Kubendran Naidoo at the Antiviral Gene Therapy Research Unit (AGTRU) and Wits Vaccines and Infectious Diseases Analytics (VIDA) research unit, will, instead of relying on complex and costly mammalian cell systems, use naturally occurring fungi, such as those found in compost, to produce vaccine proteins.

Cervical cancer is the second most common cancer among women in South Africa and the leading cause of cancer-related death in those aged 15 to 44. While HPV infection is common, cervical cancer is largely preventable.

Current HPV vaccines are effective but expensive to produce and distribute at scale. Supply disruptions during Covid-19 exposed how fragile access can be, particularly for low- and middle-income countries.

The C1 vaccine system is particularly promising in its efficiency:

“We can produce high yields of protein in a short time, using simpler workflows and cheaper, animal-free growth media. Stable production systems, meaning cells that can reliably produce the same protein over time, can be developed in about a month, compared to several months for conventional methods,” explains Naidoo.

While older vaccines used weakened or inactivated viruses, newer approaches use only key viral proteins.

“You don’t need the whole virus,” says Naidoo. “You can just make the protein that the immune system needs to recognise.”

For HPV vaccines, these proteins can be assembled into structures that mimic the virus without causing infection, allowing the immune system to recognise and respond to it.

By engineering cancer-causing strains of the virus and optimising how these proteins are produced and collected, the team is working towards a more efficient and affordable way to make HPV vaccines.

South Africa launched a national HPV vaccination campaign in 2014, reaching about 3.6 million schoolgirls and administering over 7.2 million doses. Coverage has remained high, and the country has recently shifted to a single-dose schedule to further expand access.

Encouragingly, since the advent of vaccines, HPV prevalence among adolescent girls has declined by 80% even in high-risk settings.

However, Dr Rebecca van Dorsten, a researcher at AGTRU and Wits VIDA, explains that cervical neoplasia (abnormal cells) is associated with a broader range of high-risk HPV types than those targeted by the current vaccine (which aims to prevent strains 16 and 18):

“While HPV 16 and 18 remain dominant at 34.7% and 11.4% respectively, other cancerous strains, such as HPV-35, are of significant concern. Indeed, the existing vaccines may only cover around 36% of oncogenic strains found in cervical cancer in South Africa.”

Now, Naidoo and van Dorsten believe the C1 platform may be the key to expanding the vaccination campaign because it will significantly reduce vaccine costs, potentially to less than a dollar per dose. “We can certainly implement this in low- and middle-income countries,” says van Dorsten.

While Africa has a strong capacity for clinical trials, there is less capacity to manufacture vaccines locally. Even when research is done on the continent, production happens elsewhere. “The C1 is an opportunity to introduce locally relevant vaccine design,” says Naidoo.

The platform is already being tested for Rift Valley fever, a zoonotic disease expected to increase with climate change. Early studies show that C1-produced vaccine candidates can trigger protective immune responses in animals. The same approach is being extended to next-generation HPV vaccines.

The C1 platform was conceptualised by Dyadic International, with partners such as AGTRU and Wits VIDA advancing the technology.

(Newswise/HG)