Prostaglandin A1 inhibits the replication of Sindbis virus in monkey kidney and mosquito cells

The present study reports the effect of prostaglandin A1 (PGA1) on the replication of Sindbis virus in monkey kidney and mosquito cells. In PGA1 treated cells we observed a severe reduction of virus yield. In both cells lines the highest nontoxic concentration of PGA1 (10 ìg/mL) decreased virus replication, dose dependently, by more than 90 por cento. SDS-PAGE analysis of [35S] methionine labeled proteins showed that viral proteins (E1/E2 and C) were normally synthesized in PGA1 treated Vero cells, and induction of stress proteins (HSP70 and HSP90 ) was detected in uninfected and infected cells. In Vero cells the inhibition of virus replication was accompanied by a decrease in [3H] glucosamine incorporation into the virus glycoproteins.

The dolabellane diterpene Dolabelladienetriol is a typical noncompetitive inhibitor of HIV-1 reverse transcriptase enzyme.

We recently described that a dollabelane diterpene isolated from the marine algae Dictyota pfaffii (Dolabelladienetriol) inhibits the human immunodeficiency virus type 1 (HIV-1) enzyme reverse transcriptase (RT), and HIV-1 replication in primary cells. Based on these findings, we investigated additional antiretroviral properties of Dolabelladienetriol. Here, we describe that Dolabelladienetriol blocked the synthesis and integration of HIV-1 provirus and completely abrogated viral replication in primary cells. Also, studies of kinetic mode of action revealed that the Dolabelladienetriol is a nonnucleoside RT inhibitor (NNRTI), acting as a noncompetitive inhibitor, with a K(i) value equal to 7.2 microM. To assess whether Dolabelladienetriol could potentiate the anti-HIV-1 effects of other HIV-1 inhibitors, HIV-1-infected cells were treated with Dolabelladienetriol at its EC(50) dose plus sub-optimal concentrations of classical antiretrovirals. Dolabelladienetriol provided an additive effect with the nucleoside RT inhibitor AZT, and a synergistic effect with the protease inhibitor atazanavir sulphate. There was no increment of the anti-HIV-1 effect resulting from the combination between Dolabelladienetriol and the NNRTI nevirapine. Using a large panel of HIV-1 isolates harboring NNRTI resistance mutations, we found no cross-resistance between Dolabelladienetriol and clinical available NNRTIs. Thus, Dolabelladienetriol is an NNRTI, with potent activity against HIV-1 isolates carrying common NNRTI-associated resistance mutations. Dolabelladienetriol may be considered as a potential new agent for anti-HIV-1 therapy.

Genetic variation of foot-and-mouth disease virus isolates recovered from persistently infected water buffalo (Bubalus bubalis).

Genetic variation of foot-and-mouth disease virus (FMDV) isolates, serotype O, recovered serially over a 1-year period from persistently infected buffalos was assessed. The persistent state was established experimentally with plaque-purified FMDV, strain O(1)Campos, in five buffalos (Bubalus bubalis). Viral isolates collected from esophageal-pharyngeal (EP) fluids for up to 71 weeks after infection were analyzed at different times by nucleotide sequencing and T(1) RNase oligonucleotide fingerprinting to assess variability in the VP1-coding region and in the complete genome, respectively. Genetic variation increased, although irregularly, with time after infection. The highest values observed for the VP1-coding region and for the whole genome were 2.5% and 1.8%, respectively. High rates of fixation of mutations were observed using both methodologies, reaching values of 0.65 substitutions per nucleotide per year (s/nt/y) and 0.44s/nt/y for nucleotide sequencing and oligonucleotide fingerprinting, respectively, when selected samples recovered at close time periods were analyzed. The data herein indicate that complex mixtures of genotypes may arise during FMDV type O persistent infection in water buffalos, which can act as viral reservoirs and also represent a potential source of viral variants. These results fit within the quasi-species dynamics described for FMDV, in which viral populations are constituted by related, non-identical genomes that evolve independently from each other, and may predominate at a given time.

The fusogenic state of Mayaro virus induced by low pH and by hydrostatic pressure.

Mayaro virus is an enveloped virus that belongs to the Alphavirus genus. To gain insight into the mechanism involved in Mayaro virus membrane fusion, we used hydrostatic pressure and low pH to isolate a fusion-active state of Mayaro glycoproteins. In response to pressure, E1 glycoprotein undergoes structural changes resulting in the formation of a stable conformation. This state was characterized and correlated to that induced by low pH as measured by intrinsic fluorescence, 4,4'-dianilino-1,1'-binaphthyl-5,5'-disulfonic acid, dipotassium salt fluorescence, fluorescence resonance energy transfer, electron microscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In parallel, we used a neutralization assay to show that Mayaro virus in the fusogenic state retained most of the original immunogenic properties and could elicit high titers of neutralizing antibodies.

Inhibition of vesicular stomatitis virus replication by prostaglandin A1 in Aedes albopictus cells.

Cyclopentenone prostaglandins (PGs) exhibit antiviral activity against RNA and DNA viruses in mammalian cell lines, and this effect has been associated with the induction of a heat shock protein (hsp70). We investigated the effect of prostaglandin A1 (PGA1) on the replication of vesicular stomatitis virus (VSV) in Aedes albopictus (mosquito) cells. PGA1 was found to inhibit VSV replication dose dependently. Virus yield was reduced to 50% (3 microg PGA1/ml) and to 95% with 8 microg PGA1/ml. Even with the dramatic reduction of virus production observed in cells treated with PGA1, VSV-specific protein synthesis was unaltered. Treatment of cells with PGA1 (5 microg/ml) stimulated the synthesis of a polypeptide identified as a heat-shock protein (hsp) by immunoblot analysis. PGA1 induced hsp70 synthesis in uninfected cells. However, in VSV-infected cells the induction of hsp70 by PGA1 was reduced. This is the first report of antiviral effects of PGs affecting the replication of VSV in a mosquito cell line.