Advancement in the Development of Therapeutics Against Zika Virus Infection

PfAgo-Based Zika Virus Detection

As a mosquito-borne flavivirus, Zika virus (ZIKV) has been identified as a global health threat. The virus has been linked to severe congenital disabilities, including microcephaly and other congenital malformations, resulting in fatal intrauterine death. Therefore, developing sensitive and specific methods for the early detection and accurate diagnosis of the ZIKV is essential for controlling its spread and mitigating its impact on public health. Herein, we set up a novel nucleic acid detection system based on Pyrococcus furiosus Argonaute (PfAgo)-mediated nucleic acid detection, targeting the non-structural protein 5 (NS5) region of the ZIKV genome (abbreviated ZIKV-PAND). Without preamplification with the polymerase chain reaction (PCR), the minimum detection concentration (MDC) of ZIKV-PAND was about 10 nM. When introducing an amplification step, the MDC can be dramatically decreased to the aM level (8.3 aM), which is comparable to qRT-PCR assay (1.6 aM). In addition, the diagnostic findings from the analysis of simulated clinical samples or Zika virus samples using ZIKV-PAND show a complete agreement of 100% with qRT-PCR assays. This correlation can aid in the implementation of molecular testing for clinical diagnoses and the investigation of ZIKV infection on an epidemiological scale.

Plant-expressed Zika virus envelope protein elicited protective immunity against the Zika virus in immunocompetent mice

Zika virus infection causes multiple clinical issues, including Guillain-Barré syndrome and neonatal malformation. Vaccination is considered as the only strategy for the prevention of ZIKV-induced clinical issues. This study developed a plant-based recombinant vaccine that transiently expressed the ZIKV envelope protein (ZikaEnv:aghFc) in Nicotiana benthamiana and evaluated the protective immunity afforded by it in immunocompetent mice. ZikaEnv:aghFc induced both humoral and cellular immunity at a low dose (1-5 μg). This immune-inducing potential was enhanced further when adjuvanted CIA09A. In addition, antigen-specific antibodies and neutralizing antibodies were vertically transferred from immunized females to their progeny and afforded both protective immunity to ZIKV and cross-protection to Dengue virus infection. These results suggest that our plant-based ZIKV vaccine provides a safe and efficient protective strategy with a competitive edge.

Zika virus remodelled ER membranes contain proviral factors involved in redox and methylation pathways

Zika virus (ZIKV) has emerged as a global health issue, yet neither antiviral therapy nor a vaccine are available. ZIKV is an enveloped RNA virus, replicating in the cytoplasm in close association with ER membranes. Here, we isolate ER membranes from ZIKV-infected cells and determine their proteome. Forty-six host cell factors are enriched in ZIKV remodeled membranes, several of these having a role in redox and methylation pathways. Four proteins are characterized in detail: thioredoxin reductase 1 (TXNRD1) contributing to folding of disulfide bond containing proteins and modulating ZIKV secretion; aldo-keto reductase family 1 member C3 (AKR1C3), regulating capsid protein abundance and thus, ZIKV assembly; biliverdin reductase B (BLVRB) involved in ZIKV induced lipid peroxidation and increasing stability of viral transmembrane proteins; adenosylhomocysteinase (AHCY) indirectly promoting m6A methylation of ZIKV RNA by decreasing the level of S- adenosyl homocysteine and thus, immune evasion. These results highlight the involvement of redox and methylation enzymes in the ZIKV life cycle and their accumulation at virally remodeled ER membranes.

Wulfenioidins D-N, Structurally Diverse Diterpenoids with Anti-Zika Virus Activity Isolated from Orthosiphon wulfenioides

Eleven diterpenoids, wulfenioidins D-N (1-11), classified into five distinct carbon skeletons with one unreported framework, and four modified abietane diterpenoids were isolated from the whole plant of Orthosiphon wulfenioides. The structures and absolute configurations were characterized by spectroscopic methods, single-crystal X-ray diffraction, and electronic circular dichroism analyses. Compounds 3 and 5 exhibited activity against Zika virus (ZIKV) with EC50 values of 8.07 and 8.50 μM, respectively, and showed no significant cytotoxicity toward Vero cells at 100 μM. Western blot and immunofluorescence experiments showed that compounds 3 and 5 interfered with the replication of the ZIKV by inhibiting the expression of the ZIKV envelope (E) protein.

Mechanisms of Zika astrocyte infection and neuronal toxicity

Objectives

Zika virus (ZIKV) has become an epidemic in several countries and was declared a major public health issue by the WHO. Although ZIKV infection is asymptomatic or shows mild fever-related symptoms in most people, the virus can be transmitted from a pregnant mother to the fetus, resulting in severe brain developmental abnormalities, including microcephaly. Multiple groups have identified developmental neuronal and neuronal progenitor compromise during ZIKV infection within the fetal brain, but little is known about whether ZIKV could infect human astrocytes and its effect on the developing brain. Thus, our objective was to determine astrocyte ZiKV infection in a developmental-dependent manner.

Methods

We analyze infection of pure cultures of astrocytes and mixed cultures of neurons and astrocytes in response to ZIKV using plaque assays, confocal, and electron microscopy to identify infectivity, ZIKV accumulation and intracellular distribution as well as apoptosis and interorganelle dysfunction.

Results

Here, we demonstrated that ZIKV enters, infects, replicates, and accumulates in large quantities in human fetal astrocytes in a developmental-dependent manner. Astrocyte infection and intracellular viral accumulation resulted in neuronal apoptosis, and we propose astrocytes are a ZIKV reservoir during brain development.

Conclusions

Our data identify astrocytes in different stages of development as major contributors to the devastating effects of ZIKV in the developing brain.