Sensitivity of HIV-1 to heat is Env-dependent.

<p>HIV-1 PSVs on a pSG3Δenv backbone and bearing Env from strains ADA or JR-CSF, were concentrated (20×) in PBS and incubated for 1 h at 1, 2 or 5 times their original concentration at various temperatures for 1 h prior to determination of infectivity using TZM-bl cells. (<b>A</b>) Absolute infectivity following heat treatment of HIV-1 PSVs at different virus input levels over a >10-fold range (1×10⁵–2×10⁶ RLU/0.1 ml, demarcated by triangles). (<b>B</b>) Data from panel A normalized for input infectivity, indicating T₉₀ value is independent of virus input. HIV-1 PSVs used in panel A were examined for relative levels of p24 (<b>C</b>), and gp120 (<b>D</b>), using p24 or gp120 ELISA, respectively. (<b>E</b>) Reproducibility of T₉₀ determination using independent stocks of HIV-1 PSVs (JR-CSF and ADA). (<b>F</b>) Relative infectivities of HIV-1 PSVs (JR-CSF and ADA) following several different pre-incubation temperatures and times, as determined using the TZM-bl assay. (<b>G</b>) Relative infectivity over time at physiological temperature (37°C) of HIV-1 PSVs (JR-CSF and ADA). Half-life (t_1/2) of infectivity was calculated as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0021339#s2" target="_blank">Materials and Methods</a> and is indicated near the point of half-maximal infectivity for each curve.