Inhibitory activity of human immunodeficiency virus aspartyl protease inhibitors against Encephalitozoon intestinalis evaluated by cell culture-quantitative PCR assay.
Immune reconstitution might not be the only factor contributing to the low prevalence of microsporidiosis in human immunodeficiency virus (HIV)-infected patients treated with protease inhibitors, as these drugs may exert a direct inhibitory effect against fungi and protozoa. In this study, we developed a cell culture-quantitative PCR assay to quantify Encephalitozoon intestinalis growth in U-373-MG human glioblastoma cells and used this assay to evaluate the activities of six HIV aspartyl protease inhibitors against E. intestinalis. A real-time quantitative PCR assay targeted the E. intestinalis small-subunit rRNA gene. HIV aspartyl protease inhibitors were tested over serial concentrations ranging from 0.2 to 10 mg/liter, with albendazole used as a control. Ritonavir, lopinavir, and saquinavir were able to inhibit E. intestinalis growth, with 50% inhibitory concentrations of 1.5, 2.2, and 4.6 mg/liter, respectively, whereas amprenavir, indinavir, and nelfinavir had no inhibitory effect. Pepstatin A, a reference aspartyl protease inhibitor, could also inhibit E. intestinalis growth, suggesting that HIV protease inhibitors may act through the inhibition of an E. intestinalis-encoded aspartyl protease. These results showed that some HIV protease inhibitors can inhibit E. intestinalis growth at concentrations that are achievable in vivo and that the real-time quantitative PCR assay that we used is a valuable tool for the in vitro assessment of the activities of drugs against E. intestinalis.
Menotti
Jean
J
Laboratoire de Parasitologie-Mycologie, Hôpital Saint Louis, 1 avenue Claude Vellefaux, 75475 Paris Cedex 10, France. jean.menotti@sls.ap-hop-paris.fr
Santillana-Hayat
Maud
M
Cassinat
Bruno
B
Sarfati
Claudine
C
Derouin
Francis
F
Molina
Jean-Michel
JM
D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000037:antagonists & inhibitors*; D045744:Cell Line, Tumor; D016054:DNA, Protozoan / Q000032:analysis; D004275:DNA, Ribosomal / Q000032:analysis; D016819:Encephalitozoon / Q000187:drug effects* / Q000235:genetics / Q000254:growth & development; D020459:Genes, rRNA; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D006801:Humans; D021261:Parasitic Sensitivity Tests; D016133:Polymerase Chain Reaction / Q000379:methods*
D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D017320:HIV Protease Inhibitors; D016282:Aspartic Acid Endopeptidases