Funding Information: The authors thank J.M. Cristóvão and J. Ramada for technical assistance. Funding for this work was provided by the project research grant POCTI/CVT/37759/2001 by the Fundação para a Ciência e Tecnologia (FCT), Portugal partially supported by the European Union Fund (FEDER), and grant SFRH/BD/997/2000 from FCT.; Specific immune responses by CD4+ and CD8+ T cells, from two infected mice strai...