# LncSMIM14 Hijacks Rab3a-Mediated Endocytosis to Promote Bovine Viral Diarrhea Virus Replication

## TL;DR

This study shows how a host long non-coding RNA, lncSMIM14, helps BVDV replicate by controlling Rab3a-mediated endocytosis in cattle cells.

## Contribution

The study identifies lncSMIM14 as a novel host factor that promotes BVDV replication via Rab3a-mediated endocytosis.

## Key findings

- lncSMIM14 overexpression increases BVDV replication, while its knockdown reduces it.
- Rab3a is essential for BVDV replication and is regulated by lncSMIM14.
- lncSMIM14 and Rab3a promote endocytic vesicle formation after BVDV infection.

## Abstract

Bovine Viral Diarrhea Virus (BVDV) poses a significant threat to the global cattle industry, causing substantial economic losses. Long non-coding RNAs (lncRNAs) play crucial regulatory roles in various biological processes, including viral infections. However, the specific lncRNAs influencing BVDV replication remain poorly characterized. This study identified lncSMIM14 as a key host factor upregulated during BVDV infection in MDBK cells. Functional analyses demonstrated that lncSMIM14 overexpression significantly enhanced BVDV replication, evidenced by increased viral mRNA levels, progeny virus titers, cytopathic effects, and dsRNA abundance, while its knockdown exerted the opposite effect. Mechanistically, we revealed that lncSMIM14 specifically targets and positively regulates the expression of the endocytosis-related GTPase Rab3a. Importantly, Rab3a itself was shown to be essential for efficient BVDV replication, as its overexpression promoted viral replication, and its knockdown inhibited it. Furthermore, Rab3a co-localized with key endocytic regulators Rab5a and Rab7a, and both lncSMIM14 overexpression and Rab3a overexpression promoted the formation of endocytic vesicles, particularly post-BVDV infection. Our findings unveil a novel mechanism wherein BVDV exploits the host lncRNA lncSMIM14 to hijack Rab3a-mediated endocytosis, facilitating its own replication. This study identifies the lncSMIM14-Rab3a axis as a critical host pathway subverted by BVDV, providing new potential targets for antiviral intervention.