In short
Neisseria meningitidis group W135 polysaccharide is a bacterial sugar molecule used as the active antigen in several conjugate vaccines against invasive meningococcal disease. It is not a medicine given on its own but a component of combination vaccines such as MenQuadfi, Menveo and Nimenrix, where it is chemically linked to a carrier protein.
Key points
- Neisseria meningitidis group W135 polysaccharide is a purified sugar antigen from the bacterial serogroup W-135.
- It is a component of conjugate vaccines including MenQuadfi, Menveo and Nimenrix, not a standalone medicine.
- The vaccines containing it are approved for people aged 2 years and older to prevent invasive meningococcal disease caused by serogroups A, C, W and Y.
- One Phase 2 interventional trial (NCT06989359) includes Nimenrix, which contains the W135 polysaccharide, and plans to enrol 45 participants.
- The trial investigates safety and tolerability in complement-mediated kidney disease and is currently authorised.
- The W135 polysaccharide is given as part of a 0.5 ml intramuscular injection in the approved vaccines.
What is Neisseria meningitidis group W135 polysaccharide?
Neisseria meningitidis group W135 polysaccharide is a group-specific polysaccharide antigen extracted and purified from the bacterium Neisseria meningitidis serogroup W-135. It is the sugar capsule that surrounds the bacterial cell and is recognised by the human immune system. The substance is also known by several other names, including meningococcal polysaccharide antigen group W-135 and Neisseria meningitidis group W-135 capsular polysaccharide antigen. In the NHS dm+d browser it is listed as Neisseria meningitidis group W135 capsular polysaccharide protein conjugate, reflecting the form used in modern conjugate vaccines where the polysaccharide is chemically linked to a carrier protein.
The substance is not used alone as a medicine. It is one component of combination vaccines that also contain polysaccharides from meningococcal serogroups A, C and Y. Brand names for these combination vaccines include MenQuadfi, Menveo and Nimenrix. The W135 polysaccharide was first approved in the United States in 1981, in Canada in 2000, and in the European Union in 2020 as part of conjugate vaccine products. MenQuadfi received initial US approval in 2020 as a solution for intramuscular injection.
How does Neisseria meningitidis group W135 polysaccharide work?
As a polysaccharide antigen, the W135 molecule teaches the immune system to recognise the sugar capsule of Neisseria meningitidis serogroup W-135 bacteria. When the polysaccharide is conjugated — chemically linked — to a carrier protein such as tetanus toxoid, the immune response becomes stronger and longer-lasting, and it works in young children whose immune systems respond poorly to plain polysaccharide vaccines. The immune system produces antibodies against the W135 capsule, so that if the person later encounters the actual bacterium, the antibodies can help destroy it before it causes invasive disease.
Invasive meningococcal disease includes meningitis, an inflammation of the membranes around the brain and spinal cord, and meningococcemia, a bloodstream infection. The global control of these infections caused by Neisseria meningitidis is a significant public health challenge, and conjugate vaccines containing the W135 polysaccharide are a central part of current prevention strategies.
Which conditions is it used or studied for?
- Invasive meningococcal disease caused by serogroups A, C, W and Y — the approved indication for vaccines containing the W135 polysaccharide. MenQuadfi is indicated for active immunisation to prevent this disease in individuals 2 years of age and older.
- Meningococcal serogroup B disease — explicitly not covered. MenQuadfi does not prevent disease caused by serogroup B, which requires a separate vaccine such as Bexsero.
- Complement-mediated kidney disease — the condition studied in the Phase 2 trial NCT06989359, where Nimenrix, a vaccine containing the W135 polysaccharide, is given alongside other vaccines to evaluate safety and tolerability.
How is Neisseria meningitidis group W135 polysaccharide given?
Vaccines containing the W135 polysaccharide are given as a 0.5 ml dose by intramuscular injection. The approved products are formulated as solutions for injection, and in some cases as a powder and solvent that are mixed before use. The NHS dm+d browser lists three virtual medicinal products containing the W135 polysaccharide protein conjugate: a powder and solvent for solution for injection in pre-filled syringes, a powder and solvent for solution for injection in vials, and a ready-to-use solution for injection in vials. In the Phase 2 trial, Nimenrix, which contains the W135 conjugate, is administered as a 0.5 ml intramuscular injection.
What do the clinical trials show?
One interventional Phase 2 trial listed on ClinicalTrials.gov, NCT06989359, includes the W135 polysaccharide within the Nimenrix vaccine. The trial is authorised and plans to enrol 45 participants with complement-mediated kidney disease. Its primary outcome is the incidence and severity of treatment-emergent adverse events (TEAEs), meaning the trial measures how often side effects occur and how serious they are after vaccination. The trial also includes several other vaccines — Prevenar 20, Infanrix hexa and Bexsero — as well as an investigational drug, ADX-038, given by subcutaneous injection. The W135 polysaccharide is therefore not the main focus of this trial but is present as part of a vaccination regimen being tested for safety in this patient group.
What side effects are known?
The sources provided do not contain a specific list of side effects for the W135 polysaccharide alone. The US prescribing information for MenQuadfi, a vaccine containing the W135 conjugate, describes the product as a vaccine for intramuscular injection but the excerpt provided does not include a detailed adverse reactions section. The Phase 2 trial is measuring the incidence and severity of treatment-emergent adverse events as its primary outcome, which will provide safety data in people with complement-mediated kidney disease. The review article on meningococcal vaccines discusses the development and use of conjugate vaccines but does not list specific side effects in the provided excerpt.