Nef expression and progeny virus production. Panel A: Western blot detection of control strains NL4.3-NefSF2 and NL4.3-ΔNef and two representative EC and CP-derived Nefs using two different polyclonal anti-Nef sera. Panel B: Relative band intensity of EC (red) and CP (blue)-derived Nefs as detected by Western blot. Open circles identify the representative data shown in panel A. Bars depict median and interquartile ranges. Statistical significance assessed using Mann–Whitney U-Test. Panel C: Virus production (measured as p24Gag in culture supernatant) of EC (red) and CP (blue) Nef recombinant viruses.