Dendritic cells and HIV

Question 1

What is the main recognition receptor of HIV-1?

Answer 1

Gp120/gp41 membrane.

Question 2

HIV-1 infects mucosal sites, how does it end up in CD4+ T-cells in the end?

Answer 2

CD4+ T-cells are not present at mucosal sites (main location of infection) but DCs bind HIV-1 with DC-SIGN (which bind glycans). HIV gp120 is covered with mannosylated glycan structures which are bound by DC-SIGN on DCs. HIV-1 is kept inside early endosomes in DCs, so this could mean they escape out there. DC-sign facilitates HIV transmission to CD4+ T cells.

Question 3

What is trans-infection?

Answer 3

Cell to cell infection.

Question 4

What cis-infection?

Answer 4

Direct infection of the virus into the DC-SIGN+ cell.

Question 5

How do Langerhans cells play a role in HIV-1 transmission?

Answer 5

Langerin is expressed on LCs and is the major receptor for HIV-1, and when it binds it is internalized into Birbeck granules. After internalization HIV-1 is degraded and so LCs are an innate anti-HIV-1 defense mechanism.

Question 6

What are risk factors for increased HIV-1 susceptibility?

Answer 6

High viral loads, HIV subtypes (founder strains), and co-infection hamper the Langerin-mediated protection.