Enhancing half-life and cytotoxicity of porcine respiratory and reproductive syndrome virus soluble receptors by taming their Fc domains

Xiaoming Liu; Xiaohui Zhou; Aziz Ullah Noor; Xinyu Zhang; Chengyi Song; Huaichang Sun

doi:10.1016/j.vetmic.2022.109526

Enhancing half-life and cytotoxicity of porcine respiratory and reproductive syndrome virus soluble receptors by taming their Fc domains

Vet Microbiol. 2022 Oct:273:109526. doi: 10.1016/j.vetmic.2022.109526. Epub 2022 Aug 5.

Authors

Xiaoming Liu¹, Xiaohui Zhou¹, Aziz Ullah Noor¹, Xinyu Zhang¹, Chengyi Song², Huaichang Sun³

Affiliations

¹ The College of Veterinary Medicine, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China.
² The College of Animal Science and Technology, Yangzhou University, Yangzhou 225009, China.
³ The College of Veterinary Medicine, Jiangsu Co-Innovation Center for Prevention and Control of Important Animal Diseases and Zoonoses, Yangzhou University, Yangzhou 225009, China. Electronic address: sunh@yzu.edu.cn.

PMID: 35988378
DOI: 10.1016/j.vetmic.2022.109526

Abstract

Porcine reproductive and respiratory syndrome virus (PRRSV) is an important pathogen. Although tremendous effort has been made for the vaccine development, only modified live vaccines are widely used with arguably limited efficacy. Our previous study showed that the Fc-fused first four Ig-like domains of Sn (Sn4D-Fc) and the SRCR domains 5-9 of CD163 (SRCR59-Fc) can act as PRRSV soluble receptors (VSRs). In this study, we improved the VSR-based anti-PRRSV strategy by taming their Fc domains. Sequence alignment showed that the CH3 domain of pig IgG1 contained five putative amino acids involved in the interaction with the neonatal Fc receptor (FcRn). The M455L/N461S variant of SRCR59-Fc/Sn4D-Fc was created for the higher affinity of FcRn binding. Both rBac-SRCR59-lsFc/Sn4D-lsFc and rBac-SRCR59-Fc/Sn4D-Fc expressing the mutated or wild-type VSRs were generated for conceptual validation. Both immunofluorescence and Western blotting analysis showed that the two rBac vectors could express the encoded VSRs in cells with similar expression levels and anti-PRRSV effects. In the rBac-injected mice, the expression of SRCR59-lsFc/Sn4D-lsFc was significantly prolonged than that of SRCR59-Fc/Sn4D-Fc. Both plasma stability and serum half-life of the purified SRCR59-lsFc/Sn4D-lsFc were significantly improved than that of SRCR59-Fc/Sn4D-Fc. SRCR59-lsFc/Sn4D-lsFc-treated peripheral blood mononuclear cells showed significantly stronger cytotoxicity on PRRSV-infected primary alveolar macrophages than SRCR59-Fc/Sn4D-Fc-treated cells. For the first time, we demonstrated that both half-life and effector function of pig IgG Fc-fused proteins could be significantly improved by taming their CH3 domains. The rBac-SRCR59-lsFc/Sn4D-lsFc could be further developed as a novel anti-PRRSV reagent.

Keywords: Cytotoxicity enhancement; Fc domain engineering; Half-life extension; Porcine reproductive and respiratory syndrome virus; Virus soluble receptors.

MeSH terms

Animals
Half-Life
Leukocytes, Mononuclear
Macrophages, Alveolar
Mice
Porcine Reproductive and Respiratory Syndrome* / metabolism
Porcine Reproductive and Respiratory Syndrome* / prevention & control
Porcine respiratory and reproductive syndrome virus* / genetics
Protein Domains
Swine
Swine Diseases* / metabolism