Chikungunya and Zika Viruses: Co-Circulation and the Interplay between Viral Proteins and Host Factors

IFITMs exhibit antiviral activity against Chikungunya and Zika virus infection via the alteration of TLRs and RLRs signaling pathways

Chikungunya virus (CHIKV) poses a significant challenge as there are currently no targeted antiviral drugs or vaccines to combat this infection. Here, we demonstrate that interferon-induced transmembrane proteins (IFITMs), including IFITM1, IFITM2, and IFITM3, which are interferon-stimulated genes (ISGs), inhibit CHIKV infection in human skin fibroblasts. Overexpression of IFITMs in cells restricts viral infection, whereas knockdown of IFITMs enhances viral infection. IFITMs overexpression causes a substantial upregulation of antiviral genes, namely TLR3, TLR7, TLR8, and TLR9, and their downstream signaling molecules such as TRADD, IRAK1, TRAF6, and MAP3K7, involved in TLRs signaling pathways. Furthermore, the DHX58 gene encoding the LGP2 protein, a negative regulator of RIG-I in RLRs signaling pathways, was downregulated in the overexpressed cells. Transcription factors including interferon regulatory factors (IRF) 3/5/7, which are downstream signaling components of both TLR and RLR signaling pathways, were also upregulated, resulting in enhanced IFNs signaling. IFITMs not only inhibits the early and late stages of viral infection but can also alter the antiviral innate-immune response to restrict CHIKV infection in human skin fibroblasts. Additionally, IFITMs exhibit their antiviral activity against Zika virus (ZIKV). Altogether, these results show the broad-spectrum antiviral property of IFITMs against arboviruses in foreskin cells.

Unveiling Wolbachia transcriptomic signature in the arboviral vector Aedes aegypti

Introduction

The mosquito Aedes aegypti is the main vector of arboviral diseases such as dengue and imposes a global health burden. A promising control strategy is to infect A. aegypti populations with Wolbachia, a genus of intracellular bacteria capable of blocking arboviral infections. Enhancing and preserving the efficacy of this method will depend on a solid mechanistic knowledge of the A. aegypti-Wolbachia symbiosis. By identifying differences between Wolbachia-infected and uninfected A. aegypti, previous transcriptomic studies proposed a wide range of symbiotic interactions, but a systematic identification of consistent effects across datasets is still missing.

Methods

To identify A. aegypti genes and functions consistently affected by Wolbachia, we performed differential expression and functional enrichment analysis on published transcriptomic datasets, followed by a meta-analysis of the obtained p-values using the maxP method. Six datasets were retrieved from Gene Expression Omnibus, Sequence Read Archive and ArrayExpress (last searched in July 2024, considering lack of replication as the exclusion criteria). After discarding one dataset from wAlbB-infected cell line due to poor mapping to the A. aegypti genome, the data comprised adult female A. aegypti heads, muscles, carcasses, midguts and bodies, and Wolbachia strains wMel and wMelPop.

Results and Discussion

Meta-analysis revealed 10 and 21 consistently down- and upregulated host genes, some of which have escaped the focus of previous research, including the consistently downregulated exonuclease AAEL009650 which has a pro-dengue virus homolog in Drosophila. At the function level, we found consistent upregulation of electron transport chain (ETC), carbohydrate transport and serine-type peptidase activity and inhibition, and downregulation of DNA replication. ETC upregulation suggests an alternative mechanism for Wolbachia's induction of antiviral oxidative stress, previously attributed to dual- and NADPH-oxidases which here showed downregulation or no regulation. Through analysis of previously published datasets, this work identifies promising molecular and functional targets for future studies aimed at elucidating the most fundamental mechanisms of the A. aegypti-Wolbachia symbiosis.

Zika Virus: A Review of Biology, Clinical Impacts, and Coinfections

The Zika virus (ZIKV) gained prominence as a significant global pathogen after the 2015-2016 outbreaks associated it with an increase in neurological complications in adults and congenital malformations. Different mechanisms have been proposed by which ZIKV may cross the blood-brain barrier and reach the central nervous system to cause neuroinflammation. Although ZIKV infection triggers a robust immune response, the virus has developed different strategies to escape it. Furthermore, although the virus is present in areas with cocirculation of other pathogenic agents, few studies have evaluated the cross-immune reactions and coinfection of ZIKV. Coinfections of ZIKV with other viruses, parasites, and bacteria are described. Such interactions can worsen infections and alter the immune response, imposing new therapeutic challenges and highlighting the need for more studies in the field. In this review, we discuss various aspects of ZIKV biology, focusing on the impacts of coinfections.

Coinfection with chikungunya and Zika results in mild disease and distinct inflammatory response

Chikungunya (CHIKV) and Zika (ZIKV) viruses, both mosquito-borne, often circulate simultaneously, raising concerns about the effects of coinfection. This study evaluated cytokines, chemokines, and growth factors in 12 patients with concurrent CHIKV and ZIKV infections confirmed by RT-qPCR. Clinical data and 45 immune mediators were analyzed. Coinfected and monoinfected patients exhibited similar symptoms, although ZIKV-infected individuals experienced fewer instances of fever. No patients had persistent symptoms or required hospitalization. Chemokines CCL5, CXCL1, and CXCL10 were elevated across all groups. CHIKV-infected patients showed higher levels of CCL2, CCL4, EGF, CXCL12, and IFN-α compared to controls, while IL-1RA, IL-8, and IFN-γ were elevated in both CHIKV and coinfected groups. SCF was elevated only in the ZIKV group. Overall, CHIKV and ZIKV coinfection presented mild clinical symptoms similar to monoinfections and demonstrated a moderate inflammatory response.

Coumarin-imidazopyridine hybrids and their first-in-class ZnII metal complexes as potent dual entry and replication inhibitors of Zika viral infection

In this study, we synthesized and characterized a series of coumarin-imidazopyridine hybrid ligands (HL1-HL4) and their corresponding Zn(II) complexes (C1-C4). The ligands were synthesized via a two-step process in 56-90 % yields. The resulting ligands, were utilized to form Zn(II) complexes, characterized by conductivity measurements, HRMS, IR, 1H NMR spectroscopy and X-ray diffractions. Biological evaluations revealed that these compounds exhibited potent antiviral activity against Zika virus (ZIKV), with EC50 values ranging from 0.55 to 4.8 µM and SI of up to 1490. Notably, the complexes (the first-in-class Zn(II) anti-ZIKV complexes) generally displayed enhanced activity compared to their respective ligands, with some compounds outperforming the reference antiviral, ribavirin. The Time of Addition assay suggested that while some compounds interfere with both viral entry (with a virucidal component) and replication phases, other only acted in replication phases. These results together with molecular modeling studies on ZIKV Envelope protein and ZIKV NS2B-NS3 offered insights for their mode of actions and further optimizations.

Design, synthesis, and molecular modeling studies of novel 2-quinolone-1,2,3-triazole-α-aminophosphonates hybrids as dual antiviral and antibacterial agents

With the aim to identify new antiviral agents with antibacterial properties, a series of 2-quinolone-1,2,3-triazole derivatives bearing α-aminophosphonates was synthesized and characterized by 1H NMR, 13C NMR, 31P NMR, single crystal XRD and HRMS analyses. These compounds were examined against five RNA viruses (YFV, ZIKV, CHIKV, EV71 and HRV) from three distinct families (Picornaviridae, Togaviridae and Flaviviridae) and four bacterial strains (S. aureus, E. feacalis, E. coli and P. aeruginosa). The α-aminophosphonates 4f, 4i, 4j, 4k, 4p and 4q recorded low IC50 values of 6.8-10.91 μM, along with elevated selectivity indices ranging from 2 to more than 3, particularly against YFV, CHIKV and HRV-B14. Besides, the synthesized compounds were generally more sensitive toward Gram-positive bacteria, with the majority of them displaying significant potency against E. feacalis. Specifically, an excellent anti-enterococcus activity was obtained by compound 4q with MIC and MBC values of 0.03 μmol/mL, which were 8.7 and 10 times greater than those of the reference drugs ampicillin and rifampicin, respectively. Also, compounds 4f, 4p and 4q showed potent anti-staphylococcal activity with MIC values varying between 0.11 and 0.13 μmol/mL, compared to 0.27 μmol/mL for ampicillin. The results from DFT and molecular docking simulations were in agreement with the biological assays, proving the binding capability of hybrids 4f, 4i, 4j, 4k, 4p and 4q with viral and bacterial target enzymes through hydrogen bonds and other non-covalent interactions. The in silico ADME/Tox prediction revealed that these molecules possess moderate to good drug-likeness and pharmacokinetic properties, with a minimal chance of causing liver toxicity or carcinogenic effects.

Determinants of Chikungunya and O'nyong-Nyong Virus Specificity for Infection of Aedes and Anopheles Mosquito Vectors

Mosquito-borne diseases caused by viruses and parasites are responsible for more than 700 million infections each year. Anopheles and Aedes are the two major vectors for, respectively, malaria and arboviruses. Anopheles mosquitoes are the primary vector of just one known arbovirus, the alphavirus o'nyong-nyong virus (ONNV), which is closely related to the chikungunya virus (CHIKV), vectored by Aedes mosquitoes. However, Anopheles harbor a complex natural virome of RNA viruses, and a number of pathogenic arboviruses have been isolated from Anopheles mosquitoes in nature. CHIKV and ONNV are in the same antigenic group, the Semliki Forest virus complex, are difficult to distinguish via immunodiagnostic assay, and symptomatically cause essentially the same human disease. The major difference between the arboviruses appears to be their differential use of mosquito vectors. The mechanisms governing this vector specificity are poorly understood. Here, we summarize intrinsic and extrinsic factors that could be associated with vector specificity by these viruses. We highlight the complexity and multifactorial aspect of vectorial specificity of the two alphaviruses, and evaluate the level of risk of vector shift by ONNV or CHIKV.

Anti-Zika Virus Activity of Plant Extracts Containing Polyphenols and Triterpenes on Vero CCL-81 and Human Neuroblastoma SH-SY5Y Cells

Zika virus (ZIKV) infection is a global threat associated to neurological disorders in adults and microcephaly in children born to infected mothers. No vaccine or drug is available against ZIKV. We herein report the anti-ZIKV activity of 36 plant extracts containing polyphenols and/or triterpenes. ZIKV-infected Vero CCL-81 cells were treated with samples at non-cytotoxic concentrations, determined by MTT and LDH assays. One third of the extracts elicited concentration-dependent anti-ZIKV effect, with viral loads reduction from 0.4 to 3.8 log units. The 12 active extracts were tested on ZIKV-infected SH-SY5Y cells and significant reductions of viral loads (in log units) were induced by Maytenus ilicifolia (4.5 log), Terminalia phaeocarpa (3.7 log), Maytenus rigida (1.7 log) and Echinodorus grandiflorus (1.7 log) extracts. Median cytotoxic concentration (CC₅₀ ) of these extracts in Vero cells were higher than in SH-SY5Y lineage. M. ilicifolia (IC₅₀ =16.8±10.3 μg/mL, SI=3.4) and T. phaeocarpa (IC₅₀ =22.0±6.8 μg/mL, SI=4.8) were the most active extracts. UPLC-ESI-MS/MS analysis of M. ilicifolia extract led to the identification of 7 triterpenes, of which lupeol and a mixture of friedelin/friedelinol showed no activity against ZIKV. The composition of T. phaeocarpa extract comprises phenolic acids, ellagitannins and flavonoids, as recently reported by us. In conclusion, the anti-ZIKV activity of 12 plant extracts is here described for the first time and polyphenols and triterpenes were identified as the probable bioactive constituents of T. phaeocarpa and M. ilicifolia, respectively.

The steroidal alkaloids α-tomatine and tomatidine: Panorama of their mode of action and pharmacological properties

The steroidal glycoalkaloid α-tomatine (αTM) and its aglycone tomatidine (TD) are abundant in the skin of unripe green tomato and present in tomato leaves and flowers. They mainly serve as defensive agents to protect the plant against infections by insects, bacteria, parasites, viruses, and fungi. In addition, the two products display a range of pharmacological properties potentially useful to treat various human diseases. We have analyzed all known pharmacological activities of αTM and TD, and the corresponding molecular targets and pathways impacted by these two steroidal alkaloids. In experimental models, αTM displays anticancer effects, particularly strong against androgen-independent prostate cancer, as well as robust antifungal effects. αTM is a potent cholesterol binder, useful as a vaccine adjuvant to improve delivery of protein antigens or therapeutic oligonucleotides. TD is a much less cytotoxic compound, able to restrict the spread of certain viruses (such as dengue, chikungunya and porcine epidemic diarrhea viruses) and to provide cardio and neuro-protective effects toward human cells. Both αTM and TD exhibit marked anti-inflammatory activities. They proceed through multiple signaling pathways and protein targets, including the sterol C24 methyltransferase Erg6 and vitamin D receptor, both directly targeted by TD. αTM is a powerful regulator of the NFkB/ERK signaling pathway implicated in various diseases. Collectively, the analysis shed light on the multitargeted action of αTM/TD and their usefulness as chemo-preventive or chemotherapeutic agents. A novel medicinal application for αTM is proposed.

Human host genetics and susceptibility to ZIKV infection

Managing emerging infectious diseases is a current challenge in the fields of microbiology and epidemiology. Indeed, among other environmental and human-related factors, climate change and global warming favor the emergence of new pathogens. The recent Zika virus (ZIKV) epidemic, of which the large and rapid spread surprised the scientific community, is a reminder of the importance to study viruses currently responsible for sporadic infections. Increasing our knowledge of key factors involved in emerging infections is essential to implement specific monitoring that can be oriented according to the pathogen, targeted population, or at-risk environment. Recent technological developments, such as high-throughput sequencing, genome-wide association studies and CRISPR screenings have allowed the identification of human single nucleotide polymorphisms (SNPs) involved in infectious disease outcome. This review focuses on the human genetic host factors that have been identified and shown to be associated with the pathogenesis of ZIKV infection and candidate SNP targets.