Cidofovir

Feline morbillivirus (FeMV) is a globally emerging virus that has been linked to chronic kidney disease (CKD) in infected cats. Immunological assays, such as enzyme-linked immunosorbent assay (ELISA), are important for studying the virus and monitoring its prevalence. A study using rabbit antiserum demonstrated antigenic cross-reactivity between nucleocapsid (N) proteins of FeMV and canine distemper virus (CDV), suggesting not only the risk of false-positive anti-FeMV antibody detection in ELISAs but also potentially false-positive FeMV antigen detection in Western blotting. To examine whether such cross-reactivity occurs in tests using cat plasma samples, we developed ELISAs using affinity-purified recombinant N proteins of FeMV and CDV with expression in Escherichia coli and tested 100 cat plasma samples collected from veterinary clinics in Japan. Twenty samples were found to be positive for anti-FeMV antibodies, while 6 were positive for anti-CDV antibodies. All these latter 6 samples were double-positive for anti-FeMV antibodies. Western blotting with the purified proteins confirmed the specificity of these antibodies to their target viral antigens. A reverse transcription-quantitative PCR assay with a detection limit of 100 copies failed to detect CDV genomic RNA in these 6 double-positive samples. These results strongly suggest the cross-reactivity between anti-FeMV N protein antibodies in cat plasma samples and the CDV N protein. This antigenic cross-reactivity should be considered in future studies using immunological methods employing FeMV or CDV N proteins, or antibodies targeting them.

Liver fibrosis (LF), driven by dysregulated macrophage polarization and extracellular matrix remodeling, represents a critical and unmet therapeutic challenge in chronic liver diseases. Despite decades of research, the lack of agents targeting core transcriptional regulators of fibrogenesis underscores the urgent need for mechanism-based interventions. An integrative analysis of three single-cell transcriptomic atlases identified Early Growth Response 1 (EGR1) and Signal Transducer and Activator of Transcription 3 (STAT3) as central transcriptional regulators that orchestrate pro-fibrotic macrophage polarization and the downstream activation of fibrogenic effectors such as Arginase 1 (Arg1), Fibronectin 1 (Fn1), Osteopontin (Spp1), and Thrombospondin 1 (Thbs1). By leveraging computer-aided drug design (CADD), multi-precision virtual screening of both the FDA-approved drug library and the TCMSP drug database identified Cidofovir and Pioglitazone as novel inhibitors selectively targeting EGR1 and STAT3, respectively. Molecular dynamics simulations confirmed stable binding interactions at their DNA-binding domains. Functional validation in macrophages showed that Cidofovir suppressed EGR1 signaling and downstream fibrotic gene expression, while Pioglitazone inhibited STAT3 activity and M2 macrophage polarization. In a murine LF model, dual therapy synergistically reduced collagen deposition and hepatic stellate cell activation, exhibiting superior efficacy compared to monotherapy. This study pioneers the therapeutic repositioning of Cidofovir and Pioglitazone as dual-target transcriptional inhibitors, disrupting the EGR1/STAT3-Fn1/Spp1/Thbs1 axis to attenuate fibrotic niche formation. Our "multi-omics to bedside" framework, empowered by computer-aided drug design, not only deciphers macrophage-centric fibrogenic networks but also delivers clinically translatable candidates, bridging the gap between computational drug discovery and precision antifibrotic therapy.