Previous work has shown that capsid modifications may result in the production of thermoliable vectors. Therefore, we performed thermostability assays with our respective vectors. These particular assays are important due to the complex nature of the incorporated antigens, i.e. MPER and/or Gag. Hexon-modified vectors, as well as controls vectors, were subjected to heating at 45uC for various time points (0,5,10, 20 and 45 minutes). These vectors were then used to infect HEK293 cells. The viral infectious titers were re-determined after heating using TCID 50 assays. According to the thermostability assay Ad5/HVR2-MPER-L15DE1 was the least infectious of all the vectors, showing a dramatic infectivity reduction relative to Ad5 following incubation at 45uC for 20 or 45 minutes ( Figure 5 ). These thermostability results are similar to what we have observed with other transgeneencoding or capsid-modified vectors in our laboratory [31, 35] .