Novavax RSV F Vaccine is Highly Immunogenic With Robust Transplacental Antibody Transfer in Preclinical Maternal Immunization Model

 

GAITHERSBURG, Md., Sept. 15, 2015 (GLOBE NEWSWIRE) -- Novavax, Inc., (Nasdaq:NVAX) a clinical-stage vaccine company focused on the discovery, development and commercialization of recombinant nanoparticle vaccines and adjuvants, today announced its RSV F-protein recombinant nanoparticle vaccine candidate (RSV F Vaccine) was shown to be highly immunogenic in a guinea pig model of maternal immunization. The preclinical study was published in the journal Vaccine.¹

Direct immunization of infants is complicated by their immature immune systems which are unable to fight off viral infection early in life when infants are most vulnerable to RSV. In mammals, the passage of maternal antibodies to offspring is largely achieved either by in utero transplacental transfer of immunoglobulin G antibodies (IgG) or by postpartum breast-feeding of colostral milk containing high levels of IgG and sIgA.² For human infants, maternally-derived IgG appears to be provided entirely in utero, via transplacental Fc receptor-mediated antibody transfer.² The protective effects of human serum IgG, transferred from mothers to infants in utero,² against a number of infections, including influenza and pertussis, has been well-described.^3-5

Presumptive pregnant guinea pigs were immunized with the RSV F Vaccine on gestational days 25 and 46. The vaccine induced high levels of anti-F IgG antibodies, palivizumab-competing antibodies (PCA) and microneutralizing titers. The peer-reviewed manuscript also demonstrates transfer of placental anti-RSV antibodies, as measured by a number of immunoassays, at days 15 and 30 postpartum.

"RSV is the leading cause of infant hospitalizations in the U.S. and a significant unmet need in full-term infants," said Gregory M. Glenn, M.D., Senior Vice President, Research and Development at Novavax. "The placental architecture in guinea pigs reflects the anatomy found in humans, making them an appropriate model to evaluate placental transfer of antibodies. These preclinical data further support our RSV F Vaccine maternal immunization program, and we look forward to announcing data from our Phase 2 clinical trial to protect infants via maternal immunization this quarter."