Nanotechnology against human cytomegalovirus in vitro: polyanionic carbosilane dendrimers as antiviral agents

BACKGROUND

Human cytomegalovirus (HCMV) is a worldwide infection, causing different troublesome in immunosupressed patients and very related to Human Immunodeficiency Virus 1 (HIV-1) infection, mainly in developing countries, with a co-infection rate of 80% in Africa. The high cost of present treatments and the lack of routinely tests in these countries urge the necessity to develop new molecules or strategies against HCMV. The new treatments should be low-cost and capable of avoiding the emerging problem of resistant virus. Nanoparticles play an important role in several viral infections. Our main focus is to study the potential activity of polyanionic carbosilane dendrimers (PDC), which are hyperbranched molecules with several sulfonate or sulfate groups in their periphery, against different viruses.

RESULTS

We studied the activity of G1-S4, G2-S16 and G2-S24P PDCs in MRC-5 cell line against HCMV infection by several plaque reduction assays. Our results show that dendrimers present good biocompatibility at the concentrations tested (1-50 µM) for 6 days in cell culture. Interestingly, both G2-S16 and G2-S24P showed a remarked inhibition at 10 µM against HCMV infection. Results on attachment and virucidal assays indicated that the inhibition was not directed to the virus or the virus-cell attachment. However, results of time of addition, showed a longer lasting activity of these dendrimers in comparison to ganciclovir, and the combination of G2-S16 or G2-S24P with ganciclovir increases the HCMV inhibition around 90 %.

CONCLUSIONS

Nanotechnology, in particular polyanionic carbosilane dendrimers, have proved their potential application against HCMV, being capable of inhibiting the infection by themselves or enhancing the activity of ganciclovir, the actual treatment. These compounds represent a low-cost approach to fight HCMV infections.

Efficacy of carbosilane dendrimers with an antiretroviral combination against HIV-1 in the presence of semen-derived enhancer of viral infection

Amyloid fibrils, which are present in semen, were considered to be a cause of topical vaginal gel ineffectiveness in vivo after microbicides failed as HIV-1 prophylaxis. Therefore, it was necessary to determine whether a dendrimer was suitable for further evaluation in an in vitro model of semen-enhanced viral infection (SEVI). We demonstrated that SEVI in TZM.bl cell cultures increased the infectivity of R5-HIV-1_NL(AD8), pTHRO.c and pCH058.c isolates, causing higher IC₅₀ values for two polyanionic carbosilane dendrimers, G2-STE16 and G3-S16. However, both dendrimers maintained protection rates of 90% at non-toxic concentrations. When dendrimers were combined with Tenofovir/Maraviroc (TDF/MVC), the anti-HIV-1 effect remained at a minimum IC₅₀ increase between 1- and 7-fold in the presence of amyloid fibrils. In peripheral blood mononuclear cells (PBMC), IC₅₀ values were slightly influenced by the presence of semen. In brief, dendrimers combined with antiretrovirals showed a synergistic effect. This result plays a crucial role in new microbicide formulations, as it overcomes the negative effects of amyloid fibrils.