ABSTRACT
In order to evaluate the effects of fish recombinant interferon (rIFN) on fish pathogenic rhabdoviruses, the zebrafish (Danio rerio) IFN (DreIFN) allele B gene was cloned and expressed in Escherichia coli. In addition, the effects of recombinant DreIFN (rDreIFN) on spring viremia of carp virus (SVCV), infectious hematopoietic necrosis virus (IHNV), and vesicular stomatitis virus (VSV) were surveyed in fish and chicken cells. The mature peptide of DreIFN allele B gene encodes 163 amino acids. Residues 3 and 98 are a pair of cysteines that likely form an intrachain disulfide bridge. rDreIFN protein was detected as a band at 21.6 kDa by SDS-PAGE. The purified rDreIFN has anti-SVCV and anti-IHNV activity of 3 x 10(4) U/mg-10(7) U/mg. The results indicate that rDreIFN has higher activity against SVCV and IHNV on epithelioma papulosum cyprinid (EPC) than on grass carp (C. idellus) ovary (CO) cell lines and no activity against VSV on chick embryo fibroblasts (CEF).
Subject(s)
Infectious hematopoietic necrosis virus/drug effects , Interferon Type I/pharmacology , Vesiculovirus/drug effects , Zebrafish Proteins/pharmacology , Amino Acid Sequence , Animals , Carps , Cell Line , Chick Embryo , Chickens , Escherichia coli/genetics , Escherichia coli/metabolism , Interferon Type I/biosynthesis , Interferon Type I/genetics , Molecular Sequence Data , Recombinant Proteins , Zebrafish Proteins/biosynthesis , Zebrafish Proteins/geneticsABSTRACT
Piglets infected in utero with porcine reproductive and respiratory syndrome virus (PRRSV) are born severely immunocompromised. In this article we more closely examine the effects of in utero PRRSV infection on circulating and thymic T cell populations. Numbers of CD4+, CD8+, and dual-positive lymphocytes were quantitated in circulation and in the thymus during the 2 weeks following birth. At birth we found that the number of circulating lymphocytes was suppressed by 60%. Lymphocyte numbers were also suppressed by 42% at day 7, but by day 14 the number of lymphocytes had rebounded and was actually 47% greater than controls. At birth and day 7, a drop in the number of CD4+ cells could partially explain the suppression we observed, while the rebound in total lymphocyte numbers seen at day 14 was due to a nearly fourfold increase in the number of circulating CD8+ cells. As a result, the normal CD4+:CD8+ ratio of between 1.4 and 2.2 for neonatal pigs was reduced to 0.1-0.5. The thymuses of infected piglets were found to be 50% smaller than those of control pigs and were characterized by cortical involution and severe cortical depletion of thymocytes. Analysis of the population of thymocytes revealed that double-positive thymocytes were suppressed to a greater degree than either single positive subpopulation. In addition, we show that the number of thymocytes undergoing apoptosis was increased twofold in piglets infected with PRRSV. Taken together, these results help explain the dramatic immunosuppression observed in neonatal animals infected in utero with PRRSV.
