HIV infects macrophages and T cells when the major protein “spike” on its surface binds to CD4 and a chemokine coreceptor (CCR5 or CXCR4) on the immune cells. This spike contains a trimer of glycoprotein 120 (gp120) sitting atop trimer of gp41 embedded in the viral membrane. gp120 and gp41 are encoded by a single viral gene (Envelop), with its resulting polypeptide cleaved by the host protease Furin. Gp120 binds directly to CD4, and gp41 facilitates membrane fusion.
Image: On left, 3D structure of a single simian immunodeficiency virus (SIV) obtained with cryo-electron tomography; the architecture of SIV’s surface ‘spikes’ (blue) is similar to that of HIV. On right, 3D cryo-electron tomography reveals HIV-1’s glycoprotein “spike” in complex with a soluble CD4 protein and a coreceptor mimic (17b) at ~20 Å resolution. Three copies of the coordinates for the ternary complex between gp120 (red), soluble CD4 (yellow) and 17b (cyan) have been fitted to the density map to produce a molecular model for spike structure. Learn more in White et al (2010) and Liu et al. (2008).
Photography artist Bobby Sham shares his enthusiasm for the Petzval lens
Bobby Sham is a photography artist and large format photography and Petzval enthusiast based in Hong Kong. He is also an art administrator and the secretary of the Hong Kong Photographic Cultural Association, one of the Initiators of Hong Kong Photo Festival.
He shares with us photos that he took using a large-format camera and an original Petzval Lens, as well as his Lomography x Zenit test shots. He also grants an interview with Lomography Hong Kong and shares his enthusiasm for – and insight regarding – taking photographs with the Petzval lens. http://bit.ly/1idYG8u