Inhibition of in vitro HIV infection by dialysable leucocyte extracts

Abstract

Dialysable Leucocyte Extract (DLE) is a low molecular weight dialysable material of disrupted peripheral human leucocytes with widespread effects on the immune system. We described the in vitro anti-HIV activity of DLE as well as its three chromatographic fractions (Fa, Fb and Fc). To determine the levels of inhibition on HIV replication by DLE we infected MT-4 cell cultures, using the Bru viral isolate at 0.05, 0.1, 0.5 and 1 m.o.i. Previously, MT-4 cells cultures were treated with DLE or fractions at non-toxic concentrations. Reverse transcriptase (RT) activity and p24 antigen were evaluated in culture supernatants at seven days postinfection. No effect was observed when MT-4 cells were incubated with DLE for 3 h. Whereas inhibition of HIV production was observed when MT-4 cells were pre-treated for a longer period of time. DLE inhibited p24 production and RT activity more than 50% at 0.1 m.o.i. More than 80% of inhibition was observed for all doses of DLE tested at 0.05 m.o.i. Higher viral doses (m.o.i. 0.5 and 1) were used to assess the antiviral activity of DLE fractions. Fraction Fb inhibits viral production more than 80%. Otherwise, fractions Fa and Fc did not show inhibitory effect for any viral dose used. These results indicate that DLE is able to modulate cell susceptibility to viral infection in vitro.

Antiviral mode of action of bovine dialyzable leukocyte extract against human immunodeficiency virus type 1 infection

“…In our assays, after pretreatment of the HeLa-CD4-LTR-β-gal cells and bDLE removal prior to viral challenge, protection against infection lasted 7 hours after bDLE was removed from the extracellular compartment (Figure 5). These results indicated that bDLE could induce long-term viral inhibition through cell protection, as well as modulate cell susceptibility to viral infection in vitro , in agreement with previously reported data on DLE obtained from human donors by molecular methods [9]. …”

“…Due to the DLE immunomodulatory properties discussed before, progression to AIDS in asymptomatic HIV-1 infected individuals treated with conventional anti-retrovirals, has shown a retarded progression to AIDS under adjuvant treatment with dialyzable leukocyte extract (DLE), demonstrated by lower incidences of opportunistic infections and improved cellular immunity [9,38,44]. DLE simultaneously shows anti-HIV activity [44,47,48], modulates different types of immune effectors ( e.g ., cytokines and transcription factors)[11,47,49] and restores leukocyte subsets in treated patients [16,29,35,37].…”

“…Previous results indicated that, although pretreatment of cells (MT-4) with DLE for 3 hours had no effect, inhibition of HIV-1 production was observed when cells were pre-treated for a longer period of time (from 1 to 7 days), an effect that was characterized by the decline in TNFα and TGFβ1 gene expression and inhibition of transcriptional factors [9]. In our assays, after pretreatment of the HeLa-CD4-LTR-β-gal cells and bDLE removal prior to viral challenge, protection against infection lasted 7 hours after bDLE was removed from the extracellular compartment (Figure 5).…”

“…The bDLE used in our study was produced by the Laboratory of Immunology and Virology at the Universidad Autonoma de Nuevo Leon , Mexico, following a modified process described by Lawrence et al . [9]. The bDLE was lyophilized, tested for endogenous pyrogens using the Limulus amebocyte lysate assay (MP Biomedicals, Inc.), and determined to be free of bacterial contamination by culturing in media and in vivo mice inoculations.…”

“…DLE possess three chromatographic fractions (Fa, Fb and Fc), Fraction Fb inhibits viral production more than 80%. Therefore, fractions Fa and Fc did not show inhibitory effect for any viral dose used [9]. …”