Up to 91% of bacterial strains causing a common type of invasive serogroup B meningococcal disease in children and young adults express at least one of the antigens contained in a four-component vaccine called MenB-4C (Bexsero), according to laboratory studies conducted by investigators at the federal Centers for Disease Control and Prevention (CDC) and at GlaxoSmithKline, manufacturers of the vaccine.

The work was published in the journal mSphere.

Researchers used a laboratory test called the Meningococcal Antigen Typing System (MATS) to study the coverage potential of the MenB-4C vaccine, which was approved by the Food and Drug Administration in January 2015 for use in individuals ages 10-25 years. The vaccine contains 4 antigens to prevent invasive meningococcal disease caused by the serogroup B form of the bacteria Neisseria meningitidis: factor H binding protein (fHBP), Neisserial heparin binding protein (NHBA), Neisserial adhesin A (NadA) and PorA-containing outer membrane vesicles. These antigens are found on the bacteria, and vaccination with them helps protect an individual from infection by the bacteria that carry the antigens, contingent on their immune response to the vaccine. In the United States in 2015, serogroup B strains of the bacteria caused approximately 40% of invasive meningococcal disease in all age groups, including adolescents, and over 60% of cases in infants aged less than one year.

Researchers tested 442 N. meningitidis serogroup B bacteria collected by CDC from 2000 to 2008. The MATS test showed that 91% of these US bacterial strains express antigens similar to those contained in the MenB-4C vaccine, with an estimated coverage ranging from 88% to 97% each year.

More than half of the covered strains could be targeted by two or more antigens in the vaccine, the investigators found. MATS data indicated that NHBA was expressed by 83% of the strains, fHBP was expressed by 53% of the strains, and NadA was expressed by 2.5% of the strains.

“We are very pleased to see that it looks like the vaccine has the potential to cover most of the strains of meningococcal Group B bacteria currently circulating in the U.S.,” said lead study author Gowrisankar Rajam, PhD, health scientist at CDC. “However, we need to continue our analysis to assess the coverage of currently circulating strains in the U.S. We are confident the MATS technique will be very useful at detecting any changes in bacterial expression of these antigens.”

Another vaccine against serogroup B meningococcal disease, called Trumenba, was approved by the FDA in October 2014. Previous vaccines were available to protect against meningococcal disease caused by N. meningitidis serogroups A, C, Y and W but not against serogroup B.

Funding, material and support for the study was provided by GlaxoSmithKline Biologicals SA, manufacturer of the Bexsero meningococcal vaccine. Some of the study co-authors are employed by the company, which was involved in analysis and interpretation of the data and which was provided the opportunity to review a preliminary manuscript for accuracy.