HIV awakens retroviral zombies from cellular slumber

1 February 2008. Related: Basic science and immunology.

Richard Jefferys, TAG

Back in February the blog covered two conference presentations relating to interactions between HIV and endogenous retroviruses. [1]

The gist of the story is that cells infected with HIV appear to also produce fragments of ancient endogenous retroviruses; these remnants of past retroviral infections litter the human genome but cannot replicate or, under normal conditions, transcribe their genetic material into proteins. The HIV protein Vif seems to allow these retroviral zombies to awaken by facilitating the transcription of their genetic material.

The production of endogenous retrovirus proteins by HIV-infected cells may thus provide an additional means for the immune system to recognize and target these cells for elimination.

Because endogenous retroviruses cannot replicate, they also cannot mutate. So while the rapidly-mutating HIV typically represents a moving target for the immune system, targeting proteins from endogenous retroviruses may offer an additional, easier means for immune responses to recognize HIV-infected cells.

Keith Garrison and colleagues have now published their data showing that T cell responses to human endogenous retroviruses (HERVs) can be detected in people with HIV and, furthermore, that these T cell responses show a correlation with control of HIV replication during acute HIV infection. [2]

The data were also mentioned by senior author Doug Nixon in a recently published interview with TAG. [3] The researchers suggest that the finding may lead to novel HIV vaccine strategies targeting HERVs. However, more study of the circumstances under which otherwise healthy cells might express HERV proteins is needed in order to ascertain the safety and practicality of this idea (so far, HERV expression has been primarily reported in people with HIV and people with certain cancers such as seminoma and breast cancer).

Source:TAG Basic Science Blog (26 Nov 2007)

References:

1. Does HIV Unleash Endogenous Retroviral Elements?
   http://tagbasicscienceproject.typepad.com/tags_basic_science_vaccin/2007/02/does_hiv_unleas.html 
2. Garrison K et al. T Cell Responses to Human Endogenous Retroviruses in HIV-1 Infection. PLoS Pathogens Vol.
3. No. 11, e165 doi:10.1371/journal.ppat.0030165.
   http://pathogens.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.ppat.0030165 3. Interview with David Nixon. http://www.aidsinfonyc.org/tag/science/interviews/dnixon.html