HIV in High-def

Plaque outside Antoni van Leeuwenhoek's old house in Delft

The dark age of microbiology existed in the years preceding Antoni van Leeuwenhoek's most famous microscopic study of Delft's canal water and the investigative work of his contempories, Robert Hooke and Athanasius Kercher (who was most likely the first human to witness microscopic life). In these days we had recognised the effects of what we later called microbes but we had little evidence of what was causing them, for who could not wonder what induced a feverish, spluttering epidemic of 'flu? Nor who could not wonder what was controlling the geochemical processes occurring across the Earth?  We just did not have the tools then to probe their world any further in any scientific way.

Viruses at the crossroads of infection

Last week I wrote about a recent paper showing that in some cases influenza viruses can escape from the lungs of an infected person; here, it makes it's way to the local lymph nodes by infecting your lung's sentinal immune cells, the dendritic cells. In this instance, this mechanism is probably being used by our own body's as a defence: by capturing influenza virus in the lung we can kick start our immune system by handing it directly to T and B cells within the lymph nodes. But it can also have deadly implication, especially considering that possibly every virus will have some run in with a dendritic cell during an infection.

**for a great discussion of what goes on inside lymph nodes during the induction of an immune response, see last weeks This Week in Virology**

Complicated diagram of the role of dendritic cells in the immune response. On the left, DC's grab antigen (for example a virus) and thus move into nearby lymph nodes. Here they present antigen to T cells ( or B cells). These cells leave the lymph nodes to hunt down their specific antigenic target (shown on the right here whether the T cells move into infected tissues. What DC's can also do is carry infectious viruses into the lymph nodes where they are free to replicate inside the dense population of T and B cells. http://www.biken.osaka-u.ac.jp/COE/eng/project/images/fig-hirata-jpg.jpg