Rational Vaccines' Herpes Vaccine RVx1001 Shows Promise as a Viral Vector Platform to Express Malaria Proteins and Confer Protection against Malaria Infection in Mice According to a Recent Study Published in Vaccines

Research shows company's novel HSV-1-derived viral vaccine has significant potential to produce vaccines to combat infectious diseases including malaria.

WOBURN, Mass. and OXFORD, England, May 10, 2022 /PRNewswire/ -- Rational Vaccines, a company focused on revolutionizing the treatment and prevention of herpes to eradicate the disease, today announced that the Company's attenuated herpes simplex virus type-1 (HSV-1)-vaccine RVx1001 can be utilized as a viral vaccine vector to protect against malaria infections.

The research was conducted by a team of scientists from Louisiana State University (LSU) School of Veterinary Medicine led by Konstantin G. Kousoulas, Ph.D., professor of Virology and Biotechnology, and vice president of scientific affairs at Rational Vaccines, together with scientists from Bezmialem Vakif University Beykoz Institute of Life Sciences and Biotechnology in Istanbul, Turkey, led by Ahmed. S. I. Aly, Ph.D., associate professor. The study, "An Attenuated HSV-1 Derived Malaria Vaccine Expressing Liver-Stage Exported Proteins Induces Sterilizing Protection Against Infectious Sporozoite Challenge," was published in Vaccines and can be accessed at  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8875294/

The published study reported on the development of a highly efficacious trivalent malaria vaccine using the Rational Vaccines RVx1001 vaccine as a vector. The construction of the HSV-1 vectored vaccine expressed three liver-stage (LS) malaria parasite exported proteins (EXP1, UIS3, and TMP21) as fusion proteins with the VP26 viral capsid protein.

 Results showed that intramuscular and subcutaneous immunizations of mice with a pooled vaccine, composed of the three attenuated virus strains expressing each LS antigen, induced 100 percent sterile protection against the intravenous challenge of Plasmodium yoelii 17X-NL salivary gland sporozoites.

"These data show that the Rational Vaccines HSV-1 vaccine can be effectively utilized as a vector platform to protect against malaria and other infectious diseases.  The safety and adjuvant proportion of RVx1001 has been demonstrated in ocular and genital infections of mice, guinea pigs and non-human primates including infections of Severe Combined Immunodeficient (SCID) mice," said Dr. Kousoulas.

"Despite a decades-long focus on treating malaria, almost half of the world's population remains at risk. According to WHO, malaria case incidence reduced from 81 in 2000 to 59 in 2015 and 56 in 2019, before increasing again to 59 in 2020. The eradication of malaria now seems within reach, thanks to the versatility of our HSV-based viral vector. The platform has also been proven preclinically with both a flu vaccine and cancer vaccines. Thanks to the high loading capabilities and safety of our HSV platform, opportunities are quasi limitless," said Olivier Jarry, Chief Financial Officer, Rational Vaccines.

Human malaria is caused by five different species of Plasmodium parasites, of which P. falciparum has the highest mortality rate. In humans, the life cycle of the parasite is initiated when sporozoites are introduced into the bloodstream after the host is bitten by a malaria-infected mosquito. The sporozoites then travel to the liver, where they grow into a liver stage (LS) and mature into merozoites that are released into the bloodstream to invade erythrocytes and cause clinical manifestations of malaria infection.1 Malaria is clinically silent before the emergence of merozoites from the liver.

According to WHO's latest World malaria report, there were an estimated 241 million malaria cases and 627 000 malaria deaths worldwide in 2020. This represents about 14 million more cases in 2020 compared to 2019, and 69 000 more deaths.2 Approximately two-thirds of these additional deaths (47 000) were linked to disruptions in the provision of malaria prevention, diagnosis, and treatment during the pandemic.

In addition to Drs. Kousoulas and Aly, study co-authors included Paul J.F. Rider, Ph.D., Mohd Kamil, Ph.D., Ilknur Yilmaz, Habibe N. Atmaca, Merve Kalkan-Yazici, and Mehmet Ziya Doymaz, Ph.D.

About Rational Vaccines

Rational Vaccines is revolutionizing the treatment, prevention, and diagnosis of herpes and herpes-related diseases with its rationally engineered, live-attenuated viral immunotherapeutic and prophylactic vaccine candidates. Led by a team of world-renowned scientists, the Company is headquartered in Woburn, MA, with locations in Miami, FL, and Oxford, UK. For more information, please visit www.rationalvaccines.com.

SOURCE Rational Vaccines