Exploring the Relationship Between Lone Star Virus and Synaptogyrin-2 Using Novel Viral and Host Models of Infections

There is limited understanding of the replication and transmission of bandaviruses and the influence of host genotype in successful infection. An in vitro Bandavirus model, such as Lone Star virus (LSV, Bandavirus amblyommae), capable of propagating in standard cell lines, could provide some of this critical information. In this study, we sequenced the genome of LSV and profiled its relationship with a key host viral-interacting protein, Synaptogyrin-2 (SYNGR2), known to influence the replication of another Bandavirus, Bandavirus dabieense.Materials and Methods: The genome of the LSV TMA 1381 strain was sequenced and assembled using Oxford Nanopore Technology. The expression of SYNGR2 was profiled and annotated in Vero cells. SYNGR2 knockout (KO) Vero clones were obtained via CRISPR-Cas9 gene editing of the first exon, present in all SYNGR2 isoforms. Following LSV infection, expression of SYNGR2 and LSV titer was measured in SYNGR2-KO and wild-type cell lines.

Sequence variation and evidence of viral heterogeneity were detected across all segments of the LSV TMA 1381 strain (4 missense substitutions out of 7 single-nucleotide polymorphisms identified, q > 16). Important amino acid sequence differences for the nonstructural protein, known to directly interact with host SYNGR2, were observed between LSV and other bandaviruses (15.5-47.4%). The change in SYNGR2 expression in wild-type Vero cells was limited following LSV infection (1.77-fold). No difference in estimated LSV titer was detected between wild-type and SYNGR2-KO Vero cells (p > 0.16). Our data illustrate key distinctions from previous Bandavirus reports and underline the need for future studies to explore the mechanisms of LSV replication and pathogenesis.