Hepatitis C virus (HCV; genus Hepacivirus) represents a major public health problem, infecting about 3% of the human population. Because no animal reservoir carrying closely related hepaciviruses has been identified, the zoonotic origins of HCV still remain unresolved. Motivated by recent findings of divergent hepaciviruses in rodents and a plausible African origin of HCV genotypes, we have screened a large collection of small mammals samples from seven sub-Saharan African countries. Out of 4,303 samples screened, 80 were found positive for the presence of hepaciviruses in 29 different host species. We here report 56 novel genomes that considerably increase the diversity of three divergent rodent hepacivirus lineages. Furthermore, we provide strong evidence for hepacivirus co-infections in rodents, which were exclusively found in four sampled species of brush-furred mice. We also detect evidence of recombination within specific host lineages. Our study expands the available hepacivirus genomic data and contributes insights into the relatively deep evolutionary history of these pathogens in rodents. Overall, our results emphasise the importance of rodents as a potential hepacivirus reservoir and as models for investigating HCV infection dynamics.

Here, we report a class of tryptophan trimers and tetramers that inhibit (at low micromolar range) dengue and Zika virus infection in vitro. These compounds (AL family) have three or four peripheral tryptophan moieties directly linked to a central scaffold through their amino groups; thus, their carboxylic acid groups are free and exposed to the periphery. Structure-activity relationship (SAR) studies demonstrated that the presence of extra phenyl rings with substituents other than COOH at the N1 or C2 position of the indole side chain is a requisite for the antiviral activity against both viruses. The molecules showed potent antiviral activity, with low cytotoxicity, when evaluated on different cell lines. Moreover, they were active against laboratory and clinical strains of all four serotypes of dengue virus as well as a selected group of Zika virus strains. Additional mechanistic studies performed with the two most potent compounds (AL439 and AL440) demonstrated an interaction with the viral envelope glycoprotein (domain III) of dengue 2 virus, preventing virus attachment to the host cell membrane. Since no antiviral agent is approved at the moment against these two flaviviruses, further pharmacokinetic studies with these molecules are needed for their development as future therapeutic/prophylactic drugs.

Here, we identified a novel class of compounds, which demonstrated good antiviral activity against dengue and Zika virus infection. These derivatives constitute intermediates in the synthesis of indole (ervatamine-silicine) alkaloids and share a tetracyclic structure with an indole and a piperidine fused to a seven-membered carbocyclic ring. Structure-activity relationship studies indicated the importance of substituent at C-6 position and especially the presence of a benzylester for the activity and cytotoxicity of the molecules. In addition, the stereochemistry at C-7 and C-8 positions, as well as the presence of oxazolidine ring influenced the potency of the compounds. Mechanism of action studies with two analogues of this family (compounds 22 and trans-14) showed that this class of molecules can suppress viral infection during the later stages of the replication cycle (RNA replication/assembly). Moreover, a cell-dependent antiviral profile of the compounds against several Zika strains was observed, thus possibly implying the involvement of cellular factor(s) in the activity of the molecules. Sequencing of compounds-resistant Zika mutants revealed a single non-synonymous amino acid mutation (aspartic acid to histidine) at the beginning of the predicted transmembrane domain 1 of NS4B protein, which plays a vital role in the formation of the viral replication complex. To conclude, our study provides detailed information on a new class of NS4B-associated inhibitors and strengthens the importance of identifying host-viral interactions in order to tackle flavivirus infections.