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Vaccine Effective Against 91% of Bacteria Causing Common Invasive Meningococcal Disease in US

NOV 27, 2017 | BRIAN P. DUNLEAVY
We know “there’s an app for that.”

However, more importantly, there is likely also a vaccine for that—at least the most common type of invasive meningococcal disease in children and young adults.

In a study published in the November 15, 2017 issue of mSphere—the online, open-source journal of the American Society of Microbiology—researchers from the Division of Bacterial Diseases of the Centers for Disease Control and Prevention (CDC) and pharmaceutical giant GlaxoSmithKline (GSK) in Siena, Italy, concluded that the 4-component vaccine MenB-4C (Bexsero) is effective against up to 91% of strains of the bacteria Neisseria meningitidis, which causes meningococcal disease.

The vaccine, which is manufactured by GSK, was approved by the US Food and Drug Administration in 2015 for use in individuals between 10 and 25 years of age. It contains 4 antigens against Neisseria meningitidis: factor H binding protein, Neisserial heparin-binding protein, Neisserial adhesin A, and PorA-containing outer membrane vesicles.

“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 United States,” study co-author Gowrisankar Rajam, PhD, of the CDC, said in a statement released with the study’s publication. “However, we need to continue our analysis to assess the coverage of currently circulating strains in the United States.”

As earlier research cited by the mSphere authors notes, in the United States in 2015, serogroup B strains of Neisseria meningitidis caused approximately 40% of all cases of invasive meningococcal disease in all age groups, including adolescents, and more than 60% of cases in infants under 1 year of age. Globally, Neisseria meningitidis has been linked with approximately 50,000 deaths, and as many long-term disabilities, annually.

The CDC and GSK researchers tested 442 Neisseria meningitidis serogroup B samples collected by CDC between 2000 and 2008 using the Meningococcal Antigen Typing System (MATS) laboratory test, an enzyme-linked immunosorbent assay (ELISA)-based system. They found that, based on MATS test results, 91% of the bacterial strains that cause meningococcal disease in the United States would be covered by the MenB-4C vaccine. And, they estimated that annual vaccine coverage would range from 88% to 97%. In addition, they observed that more than half of the covered strains could be targeted by 2 or more antigens in the vaccine, with Neisserial heparin-binding protein covering 83% of strains, factor H binding protein covering 53%, PorA-containing outer membrane vesicles covering 5.9%, and Neisserial adhesin A covering 2.5%.

In their concluding remarks, the authors wrote, “A major limitation of the molecular approach to determine the potential for strain coverage by a vaccine is that it has not been possible thus far to obtain information about the expression levels of the protein encoded in the bacteria from genetic data. Expression of the protein is necessary if the bacteria are to be targeted by protective antibodies directed against the antigen of interest.”

Indeed, based on their work with the testing system, the authors noted that MATS could serve as an important tool for use “under conditions in which analyses of vaccine coverage predictions are not feasible with existing strategies, including large efficacy trials or functional antibody screening of an exhaustive strain panel.”

Dr. Rajam said, “We are confident the MATS technique will be very useful at detecting any changes in bacterial expression of these antigens.”
 
Brian P. Dunleavy is a medical writer and editor based in New York. His work has appeared in numerous healthcare-related publications. He is the former editor of Infectious Disease Special Edition.
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