The comparative profile of lymphoid cells and the T and B cell spectratype of germ-free piglets infected with viruses SIV, PRRSV or PCV2

Vet Res. 2014 Sep 4;45(1):91. doi: 10.1186/s13567-014-0091-x.

Abstract

Lymphocyte subsets isolated from germ-free piglets experimentally infected with swine influenza virus (SIV), porcine reproductive and respiratory syndrome virus (PRRSV) or porcine circovirus type 2 (PCV2) were studied and the profile of these subsets among these three infections was monitored. Germ-free piglets were used since their response could be directly correlated to the viral infection. Because SIV infections are resolved even by colostrum-deprived neonates whereas PRRSV and PCV2 infections are not, SIV was used as a benchmark for an effectively resolved viral infection. PRRSV caused a large increase in the proportion of lymphocytes at the site of infection and rapid differentiation of B cells leading to a high level of Ig-producing cells but a severe reduction in CD2-CD21+ primed B cells. Unlike SIV and PCV2, PRRSV also caused an increase in terminally differentiated subset of CD2+CD8α+ γδ cells and polyclonal expansion of major Vβ families suggesting that non-specific helper T cells drive swift B cell activation. Distinct from infections with SIV and PRRSV, PCV2 infection led to the: (a) prevalence of MHC-II+ T cytotoxic cells, (b) restriction of the T helper compartment in the respiratory tract, (c) generation of a high proportion of FoxP3+ T cells in the blood and (d) selective expansion of IgA and IgE suggesting this virus elicits a mucosal immune response. Our findings suggest that PRRSV and PCV2 may negatively modulate the host immune system by different mechanisms which may explain their persistence.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • B-Lymphocytes / virology*
  • Circoviridae Infections / immunology*
  • Circoviridae Infections / virology
  • Circovirus / physiology
  • Germ-Free Life*
  • Killer Cells, Natural / virology*
  • Orthomyxoviridae / physiology
  • Orthomyxoviridae Infections / immunology*
  • Orthomyxoviridae Infections / virology
  • Porcine Reproductive and Respiratory Syndrome / immunology*
  • Porcine Reproductive and Respiratory Syndrome / virology
  • Porcine respiratory and reproductive syndrome virus / physiology
  • Swine
  • T-Lymphocytes / virology*