IgG1 Is Required for Optimal Protection after Immunization with the Purified Porin OmpD from Typhimurium.

In mice, the IgG subclass induced after Ag encounter can reflect the nature of the Ag. Th2 Ags such as alum-precipitated proteins and helminths induce IgG1, whereas Th1 Ags, such as Typhimurium, predominantly induce IgG2a. The contribution of different IgG isotypes to protection against bacteria such as Typhimurium is unclear, although as IgG2a is induced by natural infection, it is assumed this isotype is important.

The CovS/CovR acid response regulator is required for intracellular survival of group B Streptococcus in macrophages.

Group B Streptococcus (GBS) is a leading cause of neonatal meningitis and septicemia. The ability of this organism to survive inside phagocytic cells is poorly understood but thought to be an important step for the establishment of disease in the host. Here, we demonstrate that GBS shows prolonged survival within J774 macrophages and that the capacity to survive is not significantly changed across a diverse range of strains representing different serotypes, multilocus sequence types (MLST), and sites of clinical isolation.