Human cytomegalovirus (HCMV) is a ubiquitous pathogen that can cause developmental disorders following congenital infection and life-threatening complications among transplant patients. Potent neutralizing monoclonal antibodies (MAbs) are promising drug candidates against HCMV infection.

Metastasis is a primary contributor to the low survival rates of patients with cancer. Enhanced migration and invasion are two key features of the metastatic transformation of cancer cells. Furthermore, despite the fact that overexpression of the monocarboxylate transporter (MCT)1 and 4 proteins has been found to promote the migration or invasion of cancer cells, previous findings have not been conclusive and have even been contradictory. The majority of these previous studies have relied on the silencing or inhibition of MCT1/4 expression or function in highly metastatic cell lines. Silencing can be transient or incomplete, and inhibition can result in off‑target effects. Employing a different approach, the present study stably transfected human MCT1 and MCT4 into the non‑carcinogenic murine NCTC clone 929 (L929) cell line, which had undetectable endogenous MCT1 and MCT4 expression. It was observed that overexpression of MCT4, and not MCT1, promoted the migration and invasion of L929 cells. It was also found that overexpression of an inactive form of the MCT4 transporter with a single amino acid mutation failed to promote either migration or invasion, which suggested that MCT4 activity is required. Since an epidermal growth factor receptor (EGFR) inhibitor could reverse the effect of MCT4‑overexpression, it was concluded that MCT4‑overexpression exert its functions through modulating the EGF/EGFR pathway.

Adeno-associated virus (AAV) vectors are the preferred gene delivery tool in gene therapy owing to their safety, long-term gene expression, broad tissue tropism, and low immunogenicity. Affinity ligands that can bind multiple AAV serotypes endure harsh clean-in-place (CIP) conditions and are critical for industrial-scale purification. However, current ligands lack broad serotype recognition and adequate alkaline stability, which limits their reusability in large-scale manufacturing. In this study, we employed a competitive biopanning strategy to isolate a single-domain antibody (VHH) that simultaneously binds AAV2, AAV8, and AAV9. The VHH retained structural integrity and binding activity after exposure to 0.1 M NaOH, demonstrating robust alkaline stability. Structural modeling revealed that the VHH primarily recognizes the DE loop region of the VP3 capsid protein across the three serotypes, explaining its cross-serotype reactivity. Affinity chromatography using the VHH yielded infectious AAV particles, confirming its potential for downstream processing. This strategy provides a versatile platform for developing high-performance AAV affinity ligands and may be extended to other viral vector systems.