Abstract
The infection of foetal thymus with coxsackievirus B4 (CV‐B4) E2 has been studied ex vivo by using CD‐1 mice on foetal day 14, as a ready source of organs for experimentation to investigate the hypothesis of the role of thymic viral infections in the pathogenesis of type 1 diabetes. The replication of CV‐B4 E2 in murine foetal thymus organ cultures has been demonstrated by evaluating the levels of positive‐ and negative‐stranded viral RNA in cells by using a real‐time quantitative RT‐PCR method and by determining titres of infectious viral particles in culture supernatants for 7 days post‐infection (p.i.). Staining of tissue sections with an anti‐cytokeratin antibody and haematoxylin–eosin showed that CV‐B4 infection had no visible effect on cell survival and organ integrity. Cell counts in mock‐ and virus‐infected foetal thymus organ cultures increased from day 1 through day 7, and live cell numbers were comparable in both conditions as shown by Trypan blue exclusion test and 7‐amino‐actinomycin D staining of thymocytes. Compared with controls on day 7 p.i., cytofluorometric analyses on cells from CV‐B4 E2‐infected foetal thymus organ cultures displayed a marked increase in the percentage of the most immature CD3^−^CD4^−^CD8^−^ thymocytes, and a decrease in the percentage of immature CD3^−^CD4^+^CD8^+^ cells, together with an increase in the percentage of mature CD3^+^CD4^+^ and CD3^+^CD8^+^ cells. These data show that CV‐B4 E2 disturbs T‐cell maturation and differentiation processes in infected murine foetal thymus organ cultures and provide evidence of a suitable system to investigate the effect of viruses in T‐cell differentiation. J. Med. Virol. 80:659–666, 2008. © 2008 Wiley‐Liss, Inc.