Immune correlates of protection against HIV infection and how to elicit them M Biasin 1 , D Trabattoni 1 , J-F Rossignol 2 and M Clerici 1,3 1 Department of Biomedical and Clinical Sciences, University of Milano, Milano, Italy. 2 Romark Laboratories, L.C., Tampa, Florida USA and 3 Department of Physiopathology and Trans- plants, University of Milano and Don C Gnocchi Foundation, Milano, Italy. Correspondence: M Clerici (mario.clerici@unimi.it) To the Editor: Immune correlates of protection against HIV infection are an important topic of investigation in HIV research as the analysis of such correlates could help the design of novel vaccinal and prevention approaches to the disease (reviewed in ref. 1) The definition of mucosal correlates of protection, in particular, is of extreme importance given that the vast majority of HIV infections are sexually transmitted. Veazey presents data of experiments in the animal model in which interferon beta (IFNb) was applied topically in the genital site. Not surprisingly, IFNb resulted in mucosal immune activation, but, unexpectedly, animals were pro- tected from SHIV infection. 2 We analyzed mucosal immune corre- lates of protection in highly exposed HIV Figure 1 Messenger RNA (mRNA) expression of genes that are part of the type I interferon (IFN) signal transduction pathway in peripheral blood mononuclear cells (PBMC) that were cultured in medium containing two different thiazolides: tizoxanide (TIZ) or RM-4848, and were or were not in vitro infected with HIV (the R5 tropic HIV-1BaL strain was used in the experiments shown herein). mRNA expression was assessed by real-time quantitative polymerase chain reaction, calculated relative to five housekeeping genes and shown as fold-change expression from the untreated sample. Gene expression (n-fold) is shown as a color scale from green to red (  2 to þ 9) (MEV multiple experiment viewer software); only genes that are upregulated are shown. (a) PBMC cultured in medium containing TIZ (10 mg/ml) that were either uninfected or HIV1-infected. Results at day 7 post infection are shown. (b) PBMC cultured in medium containing RM-4848 (10 mg/ml) that were either uninfected or HIV1-infected. Results at day 7 post infection are shown. LETTER TO THE EDITOR MucosalImmunology | VOLUME 10 NUMBER 3 | MAY 2017 827