Monoclonal and oligoclonal TCR AV and BV gene usage in CD4+ T cells from pigs immunised with C-strain CSFV vaccine

Chunyan Wang,Guohua Chen,Shoujie Li,Yongxiang Fang,Qiwang Jin,Huaijie Jia,Zhizhong Jing,Yuan Feng,Wenyu Cheng,Wenjuan Yao,Hong Yin,Xiaobing He,Shuang Zeng

doi:10.1038/s41598-018-19974-y

Abstract

The classical swine fever virus C-strain vaccine (C-strain vaccine) plays a vital role in preventing and controlling the spread of classical swine fever (CSF). However, the protective mechanisms of C-strain vaccine and cellular immunity conferred by T cell receptors (TCRs) are less well defined. We aimed to analyse the association between the complementarity determining region 3 (CDR3) spectratype of αβTCR in CD4+ T cells and C-strain vaccine; and to find conserved CDR3 amino acid motifs in specific TCR α- and β-chains. We found that the CDR3 spectratype showed dynamic changes correlating with C-strain vaccine immunisation and that TCR AV5S/8–3S/8–4S/14/38 and BV4S/6S/7S/15S/30 gene families showed clonal expansion in immunised pigs. The sequences of CDR3 from these clonally expanded T cells indicated a high frequency of the ‘KLX’ motif in the TCR α chain and the ‘GGX’ motif in β chain, and Jα39, Jα43, Jβ2.5 and Jβ2.3 genes were also found in high frequency. To the best of our knowledge, this is the first report describing the dynamic changes of αβTCRs and conserved CDR3 amino acid motifs in CD4+ T cells from C-strain vaccine-immunised pigs, which will provide a basis for the development of high-efficiency epitope vaccines.

Highlights

Classical swine fever (CSF) is a highly contagious disease that poses great risk to the swine industry worldwide, and it is characterised by fever, leucopenia, haemorrhage and high morbidity and mortality rates[1,2]
T cell receptors (TCRs) analysis demonstrated monoclonal/oligoclonal expansion in the peripheral blood mononuclear cells (PBMCs) of pigs infected with C-strain CSF virus (CSFV), and the sequencing of selected TCR complementarity determining region 3 (CDR3) regions indicated a high level of conserved amino acid motifs[21]
Considerable anti-CSFV antibody titres were detected in all four immunised pigs, compared with the negative controls, but different antibody titres were observed at different times

Summary

Introduction

Classical swine fever (CSF) is a highly contagious disease that poses great risk to the swine industry worldwide, and it is characterised by fever, leucopenia, haemorrhage and high morbidity and mortality rates[1,2]. As a more sensitive and accurate method, immunoscope spectratyping has been widely used to detect the clonality of T cells and to analyse the repertoire of TCR CDR3 genes[19] The principle of this technique is to design specific forward TCR AV/BV primers for each family and conserved fluorescently-labelled reverse AC/BC primers. Despite the demonstration of the relevance between clonally expanded TCR gene families and C-strain CSFV, the dynamics of the clonality of αβTCRs over time in CD4+ T cells from pigs immunised with C-strain vaccine and conserved CDR3 amino acid motifs remain unknown. To characterise the immune status of C-strain vaccine-immunised pigs, we used reverse transcription polymerase chain reaction (RT-PCR) and GeneScan analysis to monitor TCR gene usage and clonal expansion in CD4+ T cells from four C-strain vaccine-immunised pigs and two non-immunised controls over time. Our data may assist in elucidating the immunological mechanisms of the rapid protection conferred by C-strain vaccine and provide information on the design of new vaccine types

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