Lassa fever: Vaccine set to be trialed

October 24, 2019

There is currently no vaccine for the Lassa arenavirus, which causes Lassa fever. This hemorrhagic fever, endemic in West Africa, infects up to 300,000 people each year. Given the urgency of the situation, scientists in the Biology of Viral Emerging Infections Unit and the Viral Genomics and Vaccination Unit at the Institut Pasteur evaluated the efficacy of several vaccine candidates. Following their analyses, they identified one of these vaccines, based on the measles platform, as being the most effective to enter clinical testing in humans as soon as possible. This raises hopes in the fight against a disease that claims between 5,000 and 6,000 lives every year.

Lassa fever, a hemorrhagic fever caused by the Lassa virus (LASV), is responsible for several thousands of deaths in endemic countries in West Africa every year. The natural reservoir of the virus is a peridomestic rodent that lives near or inside homes, so contacts between humans and the infected reservoir in villages are frequent. Humans are generally infected by ingesting or inhaling material contaminated with the animal's excreta (urine or feces).

Early diagnosis of Lassa fever is difficult to establish because the first symptoms are non-specific (fever, vomiting and nausea), and there is currently no treatment. Vaccinating the populations concerned is therefore the most promising strategy to deal with recurrent outbreaks of Lassa fever. The World Health Organization (WHO) has included Lassa fever in its R&D Blueprint list of epidemic threats needing urgent R&D action.

Frédéric Tangy, Head of the Institut Pasteur's Viral Genomics and Vaccination Unit, said in an interview: "When it comes to vaccines, all the easy work has already been done, and the more difficult work has still not been completed. Fundamental research is vital for the development of new solutions."

To address this public health challenge, Institut Pasteur scientists have therefore developed and tested several vaccines. The results of their research were published in the journal Science Translational Medicine on October 2.

Two vaccine candidates to tackle Lassa fever

"The aim of this study was to identify the best potential vaccine for Lassa fever. We wanted a vaccine that would offer protection after a single injection so that it could be used in the urgent context of an outbreak," explains Mathieu Matéo, a scientist in the Institut Pasteur's Biology of Viral Emerging Infections Unit and lead author of the study.

The scientists used two vaccine platforms based on live attenuated viruses that had been modified to express LASV antigens: a recombinant measles vaccine strain developed by Frédéric Tangy, Head of the Institut Pasteur's Viral Genomics and Vaccination Unit, which had already produced very positive results in clinical trials for chikungunya; and a recombinant Mopeia virus, closely related to the Lassa virus but not pathogenic for humans, that was genetically hyperattenuated by the scientists.

"We compared the efficacy of these vaccines in preventing LASV infection in a preclinical animal model. The vaccines were well tolerated and induced protection against Lassa fever after a single shot, but with different levels of efficacy," continues Mathieu Matéo. A comparison of immune responses after infection demonstrated that the best protection was associated with early T and B cell immune responses directed against several Lassa virus proteins. Analyses carried out on samples taken after vaccination also suggest that early induction of innate immunity and activation of immune T cells from just two days after immunization correlates with efficient protection.

"The most effective vaccine, the one based on the measles vaccine platform expressing LASV antigens, was recently selected by the CEPI (Coalition for Epidemic Preparedness Innovations) to enter clinical trials in humans by the end of the year," concludes Sylvain Baize, Head of the Biology of Viral Emerging Infections Unit and last author of the study.
-end-


Institut Pasteur

Related Clinical Trials Articles from Brightsurf:

Nearly 1 in 5 cancer patients less likely to enroll in clinical trials during pandemic
A significant portion of cancer patients may be less likely to enroll in a clinical trial due to the ongoing coronavirus pandemic.

COVID-19 clinical trials lack diversity
Despite disproportionately higher rates of COVID-19 infection, hospitalization and death among people of color, minority groups are significantly underrepresented in COVID-19 clinical trials.

Why we should trust registered clinical trials
In a time when we have to rely on clinical trials for COVID-19 drugs and vaccines, a new study brings good news about the credibility of registered clinical trials.

Inclusion of children in clinical trials of treatments for COVID-19
This Viewpoint discusses the exclusion of children from coronavirus disease 2019 (COVID-19) clinical trials and why that could harm treatment options for children.

Review evaluates how AI could boost the success of clinical trials
In a review publishing July 17, 2019 in the journal Trends in Pharmacological Sciences, researchers examined how artificial intelligence (AI) could affect drug development in the coming decade.

Kidney patients are neglected in clinical trials
The exclusion of patients with kidney diseases from clinical trials remains an unsolved problem that hinders optimal care of these patients.

Clinical trials beginning for possible preeclampsia treatment
For over 20 years, a team of researchers at Lund University has worked on developing a drug against preeclampsia -- a serious disorder which annually affects around 9 million pregnant women worldwide and is one of the main causes of death in both mothers and unborn babies.

Underenrollment in clinical trials: Patients not the problem
The authors of the study published this month in the Journal of Clinical Oncology investigated why many cancer clinical trials fail to enroll enough patients.

When designing clinical trials for huntington's disease, first ask the experts
Progress in understanding the genetic mutation responsible for Huntington's disease (HD) and at least some molecular underpinnings of the disease has resulted in a new era of clinical testing of potential treatments.

New ALS therapy in clinical trials
New research led by Washington University School of Medicine in St.

Read More: Clinical Trials News and Clinical Trials Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.