Approaches on genetic polymorphism of Cryptococcus species complex.

Neisseria meningitidis is exclusively a human-adapted bacterium, most frequently found in asymptomatic carriage that promotes natural immunity. However, it is also the causative agent of severe invasive infections, such as septicaemia and/or meningitis that may lead to life-threatening septic shock. Vaccination with capsular polysaccharidic antigens (either plain or conjugated) induces serogroup specific protective antibodies. Meningococcal capsular polysaccharide vaccines are only available against serogroups A, C, Y and W135. There is no available capsular vaccine against serogroup B. Future strategies to develop meningococcal vaccine should be global strategies aimed to design a "universal vaccine" effective against meningococcal disease due to any strain, regardless its phenotype and genotype. However, these global strategies may be hindered by the high diversity of meningococcal isolates and their changing epidemiology. Alternatively, targeted or local vaccine strategies may be developed against specific isolates and can help particularly in controlling outbreaks while preserving benefits from carriage.