Roques, P. | bioRxiv Science

bioRxiv2024

A recombinant CHIKV-NLuc virus identifies chondrocytes as target of Chikungunya virus in a immunocompetent mouse model

First isolated in 1953 in Tanzania, the arthritogenic Chikungunya virus (CHIKV) re-emerged globally in 2005, leading to widespread outbreaks. Unlike other arboviruses, CHIKV predominantly induces symptomatic infections (72-96%), marked by fever, myalgia, polyarthralgia, and rash. Although rarely fatal, atypical forms such as encephalopathies can occur. Notably, 75.4% of patients experience persistent arthralgias for up to three years after the acute phase. Understanding CHIKVs pathophysiology in the joints is challenging due to the difficulties to obtain biological samples. The study employs a mouse model infected with a reporter virus expressing a Nano Luciferase to investigate the diseases transition to chronic arthritis. The murine model reveals viral replication in metatarsi joints, particularly in chondrocytes, confirmed in primary human chondrocytes undergoing viral-induced apoptosis. Ex vivo analysis confirmed viral replication in leg bones and articular cartilages, with histological evidence of focal erosive lesions and periarticular inflammation. The study further utilizes an in vivo imaging mouse model to monitor viral replication over time. Human chondrocytes prove susceptible to CHIKV infection, exhibiting active viral replication, bioluminescence activity, and increased viral production. CHIKV induced apoptosis, the upregulation of markers associated with cartilage remodeling and altered the cytokine production. This comprehensive study, utilizing advanced techniques and models, provides insights into CHIKVs ability to infect articular cartilages, shedding light on the mechanisms of chronic arthritis following infection.

microbiology↗

bioRxiv2020

ZIKA virus effects on neuroprogenitors are exacerbated by the main pyriproxyfen metabolite via thyroid hormone signaling disruption

North-Eastern Brazil saw intensive application of the insecticide pyriproxyfen (PPF) during the microcephaly outbreak caused by Zika virus (ZIKV). ZIKV requires the neural RNA-binding protein Musashi-1 to replicate. TH represses MSI1. Being a suspected TH disruptor, we hypothesized that co-exposure to the main metabolite of PPF, 4-OH-PPF, would exacerbate ZIKV effects through increased MSI1 expression. This was tested using in vitro mouse neurospheres and an in vivo TH signaling reporter model, Xenopus laevis. TH signaling was decreased by 4-OH-PPF in both models. In mouse-derived neurospheres the metabolite reduced neuroprogenitor proliferation as well as markers of neuronal differentiation. The results demonstrated that 4-OH-PPF significantly induced MSI1 at both the mRNA and protein level, as well as Fasn mRNA. Other TH target genes were also significantly modified. Importantly, several key genes implicated in neuroprogenitor fate and commitment were not dysregulated by 4-OH-PPF alone, but were in combination with ZIKV infection. These included the neuroprogenitor markers Nestin, Egfr, Gfap, Dlx2 and Dcx. Unexpectedly, 4-OH-PPF decreased ZIKV replication, although only at the fourth and last day of incubation, and RNA copy numbers stayed within the same order of magnitude. However, intracellular RNA content of neuroprogenitors was significantly decreased in the combined presence of the PPF metabolite and ZIKV. We conclude that 4-OH-PPF interferes with TH action in vivo and in vitro, inhibiting neuroprogenitor proliferation. In the presence of ZIKV, TH signaling pathways crucial for cortical development are significantly impacted. This provides another example of viral effects that are exacerbated by drug or pesticide use. Significance statementIn 2015, an increase in children born with unusually small heads (microcephaly) in North-Eastern Brazil was linked to infection with the ZIKA virus. An insecticide with thyroid hormone disruptive properties was used in the same areas. We investigated whether simultaneous exposure to the insecticide could increase viral susceptibility. The main metabolite 4-OH-PPF dysregulated thyroid hormone signaling pathways crucial for brain development in both models used. Neural stem cells proliferated less and contained more Musashi-1, a protein the virus needs to replicate. Infecting stem cells pre-exposed to the endocrine disruptor did not amplify viral replication, but aggravated expression of genes implicated in brain development. Our results suggest the insecticide is particularly deleterious to brain development in areas with ZIKA virus prevalence.

neuroscience↗