Chikungunya Recombinant Subunit Vaccine

7. Project Summary/Abstract
Chikungunya virus (CHIKV) is an alphavirus classified as a category C priority pathogen that causes fever,
rash, and arthralgia in humans, leading to debilitating illness and a low quality of life. In the past decade,
CHIKV outbreaks have spread beyond the endemic regions of Africa and Asia. The World Health Organization
reported in 2014 that there were over 1 million suspected cases of Chikungunya in the Caribbean islands and
Central and South American countries. While the number of cases has declined since this peak in 2014, the
geographic expansion of CHIKV has continued with the most recent outbreak occurring in Pakistan in 2016.
Estimates indicate that 1.3 billion people reside in areas at-risk for CHIKV transmission. As a result of this
increase in range and number of human cases, CHIKV is considered a re-emerging pathogen; a contributing
factor to this re-emergence is the adaptation to transmission by Aedes albopictus mosquitoes. Currently, there
are no licensed vaccines or therapeutics to protect against CHIKV infection. As with many emerging viral
infections, supportive care is the only available treatment. Given the severe morbidity caused by CHIKV, its
swift emergence, and continued expansion, a preventative vaccine is necessary to reduce the disease burden.
The leading CHIKV vaccine candidates in development are based on live-attenuated virus, chimeric live-
attenuated virus, or virus like particles. These complex compositions introduce the risk of adverse events, as
the disease mechanism of clinical CHIKV manifestations are not fully understood. Alternate vaccines utilizing
methods that can offer better safety profiles as well as benefits in manufacturing are warranted. We have
developed a promising recombinant subunit CHIKV vaccine that induces high levels of neutralizing antibodies
and prevents viral replication in immune competent mice. Our data indicate that the conformation of the E2
protein is critical to the ability to induce potent neutralizing antibody responses. This Phase II application
expands our initial efforts to develop a CHIKV recombinant subunit vaccine focused on the E2 protein. The
proposed research aims to 1) Optimize expression and purification of E2/E1 recombinant protein, 2) Evaluate
immunogenicity and protective efficacy of E2/E1 in mouse models, 3) Conduct preliminary vaccine safety
study and manufacture master cell bank, and 4) Conduct a pre-IND meeting with the FDA. As with all vaccines,
and in particular for priority pathogens such as CHIKV which requires BSL-3 handling, a combination of safety
and economics in manufacturing are of paramount importance. The proposed recombinant subunit approach
provides a means to deliver a safe, stable, and established manufacturing platform for a CHIKV vaccine.8. Project Narrative
The proposed research is focused on development of a candidate vaccine that protects against
chikungunya virus (CHIKV) which causes debilitating disease in humans. The vaccine will be based on
technology which allows for production recombinant subunit envelope proteins. Although CHIKV is not yet
established in the U.S., recent epidemics in the Americas provide the potential for the virus to become
endemic in the U.S. CHIKV is classified as a category C priority pathogen. A successful vaccine would
provide protection in counties where the virus is already established, as well as help protect against the
potential spread to the United States. The vaccine could also be used for travelers that may be at risk in
endemic areas.