Neisseria meningitidis is one of the leading causes of bacterial meningitis worldwide, affecting mainly children and young adults (Apicella, 2000). The rapid progression of meningococcal disease makes proper diagnosis and subsequent treatment often vital to the survival of infected individuals. If not properly diagnosed and treated, meningococcal infections can lead to shock and death within a matter of hours (West et al., 2001). Thus, better prevention, diagnosis and treatment of meningococcal infections would be invaluable.
N. meningitidis virulence factors include the bacteria's capsular polysaccharide, which protects the bacteria from host immune defenses; lipooligosaccharide (LOS), which is the principle glycolipid present in the bacteria's outer membrane and is composed of the oligosaccharide chain extensions, the core, and the lipid A; and class 4 outer membrane protein (OMP), also called reduction modifiable protein (Rmp). Vaccines that contain LOS may have both positive and negative side effects. For example, the LOS may function as a natural adjuvant. However, because of toxicity from the LOS, the use of the vaccine may be limited.
N. meningitidis that do not express one or more virulence factors, e.g., lipid A, which are readily grown in culture and are immunogenic, would be useful to prepare vaccines and as tools for the generation of immunological reagents.