Safety and immunogenicity in neonatal mice of a hyperattenuated Listeria vaccine directed against human immunodeficiency virus

CD8 T cells are a major component of the adaptive response of a host to infections by viruses and other intracellular pathogenic agents. However, because of the intrinsic immaturity of the immune system of neonatal animals, neonates are highly sensitive to a variety of pathogens and may be unable to respond in a protective manner. Here we explore whether a hyperattenuated strain of Listeria monocytogenes that can be used as a live vaccine vector in adults is safe and able to induce an effective response in neonates. We answer both questions affirmatively. Naı̈ve CD8 T cells are stimulated to proliferate and to develop into cytotoxic effector T cells after recognition of short peptides associated with major histocompatibility complex (MHC) class I molecules on professional antigen-presenting cells (APCs). These effector cells are a major component of the adaptive response of a host to infections by viruses and other intracellular pathogenic agents. Because of the intrinsic imma-turity of the immune system of neonatal animals, neonates are highly sensitive to a variety of these pathogens. Can youn