Researchers uncloak microbes in disguise

18 April 2009

Studies have shed new light on how HIV and the bacterium that causes meningitis evade our immune system.

Scientists from the University of Oxford and Imperial College London have discovered how Neisseria meningitidis, which is responsible for bacterial meningitis, mimics human cells to evade the immune system. They found that a protein in the outer coat of N. meningitidis enables it to bind to factor H, a molecule that circulates in the blood and normally only binds to our own cells, protecting them from our immune response.

A separate study has found a correlation between certain genes for human leukocyte antigens (HLAs) and particular mutations in HIV. HLAs differ from person to person and help our immune system to recognise and kill infected cells. Certain mutations in HIV enable the virus to evade this immune response. The study found that the more common an HLA gene is in a population, the higher the frequency of matching HIV mutations. Furthermore, the mutations can be passed onto others, even if their HLA genes differ.

Image: N. meningitidis bacteria (yellow) inside human cells. Credit: Shao Jin Ong

References

Schneider MC et al. Neisseria meningitidis recruits factor H using protein mimicry of host carbohydrates. Nature 2009;458(7240):890-93.

Kawashima Y et al. Adaptation of HIV-1 to human leukocyte antigen class I. Nature 2009;458(7238):641-45.