Interactions of Neisseria meningitidis with cells of the human meninges

The interaction of Neisseria meningitidis with the meninges that surround and protect the brain is a pivotal event in the progression of bacterial meningitis. Two models of the human meninges were established in vitro, using (i) sections of fresh human brain and (ii) cultures of viable cells grown from human meningiomas. Neisseria meningitidis showed a specific predilection for binding to the leptomeninges and meningeal blood vessels in human brain and not to the cerebral cortex. There was a close correlation between the adherence of different Neisseria species to leptomeninges and cultured cells. The major ligand that mediated adherence was the pilus, and pilin variation modulated the interactions. The presence of Opa protein increased the association of Cap+ meningococci that expressed low-adhesive pili, but did not influence the association of high-adhesive pili. In contrast, Opc did not influence the adherence of Cap+ meningococci, whereas loss of capsule was associated with a more intimate interaction between the bacteria and the meningioma cell that was not apparent with Cap+ meningococci. There was no evidence of internalization of meningococci by meningioma cells in vitro, an observation that is consistent with the barrier properties of the leptomeninges to N. meningitidis observed in vivo

Attachment of Neisseria gonorrhoeae to human sperm. Microscopical study of trypsin and iron.

Pilated Neisseria gonorrhoeae of colony type 1 (T1) and non-pilated bacteria of colony type 4 (T4) were observed by transmission (TEM) and scanning electron microscopy (SEM). No pili were observed on T4 gonogocci, but two types of pili--straight, type a, and bent, type b--were seen on T1 by TEM. When incubated with human sperum and examined by either TEM or SEM, T1 gonococci were seen to attach by individual pili, by several pili wound together as a rope, or by direct contact. Gonococci from T4 colonies attached only by direct contact. Treatment with typsin (1 mg/ml) damaged or removed pili from gonococci. After incubation with trypsin, attachment of pilated gonococci to sperm was decreased significantly, but such treatment did not affect attachment of non-pilated gonococci. Incubation of gonococci from either colony type in 0.1 mmol/l ferric nitrate, followed by incubation with sperm, significantly increased attachment of only T4 bacteria. No pili were seen on T4 gonococci treated with ferric nitrate; thus, it appears that factors other than pili alone are concerned in attachment of these gonococci to sperm