The seasonal occurrence of Ctenocephalides felis felis (Bouché ) and Ctenocephalides canis (Curtis) infestation on dogs and cats in Cuernavaca City in Mexico, was determined by examining 1,803 dogs and 517 cats at two veterinary clinics during 1995Ð1997. The overall ßea infestation was 30.3 and 30.1% for dogs and cats, respectively. There were no signiÞcant differences (P Ͼ 0.05) in percentage of infestation among years for both hosts. The infestation was somewhat higher in spring, summer, and autumn than in winter, but no statistical differences was found among seasons (P Ͼ 0.05) for both pets. No relationship existed between percentage of ßea infestation and temperature or rainfall among seasons. On dogs, 81.1% were infested with only C. felis felis, 16.8% with C. canis, and 2% had both ßea species; whereas 92.3% of the cats were infested with C. felis felis and 7.7% with C. felis felis and C. canis. The cat ßea was the most prevalent ßea species found other than C. canis; no other species were found on the dogs and cats. It appeared that ßea life cycle development continued throughout the year.

Frequencies of circulating T cells producing IFN-γ, TNF-α, and IL-2, and percentages of T cells proliferating after stimulation with rotavirus (RV), tetanus toxoid, and influenza were evaluated in PBMC derived from healthy adults and children. In addition, the potential anergic state of RV-specific T cells was analyzed by stimulation of PBMC with RV antigen in the presence of three anergy inhibitors (rIL-2, rIL-12, or DGKα-i). The quality and magnitude of RV-T cell responses were significantly lower than those of tetanus toxoid and influenza antigens. RV-CD4 T cell response was enriched in monofunctional IFN-γ(+) cells, while influenza-CD4 and tetanus toxoid-CD4 T cell responses were enriched in multifunctional T cells. Moreover, rIL-2--unlike rIL-12 or DGKα-i--increased the frequencies of RV-CD4 TNF-α(+), CD4 IFN-γ(+), and CD8 IFN-γ(+) cells. Thus, circulating RV-T cells seem to have a relatively poor functional profile that may be partially reversed in vitro by the addition of rIL-2.

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Using a consensus epitope prediction approach, three rotavirus (RV) peptides that induce cytokine secretion by CD4 T cells from healthy volunteers were identified. The peptides were shown to bind HLA-DRB1*0101 and then used to generate MHC II tetramers. RV specific T cell lines specific for one of the three peptides studied were restricted by MHC class II molecules and contained T cells that bound the tetramer and secreted cytokines upon activation with the peptide. The majority of RV and Flu tetramer+ CD4 T cells in healthy volunteers expressed markers of antigen experienced T cells, but only RV specific CD4 T cells expressed intestinal homing receptors. CD4 T cells from children that received a RV vaccine, but not placebo recipients, were stained with the RV-VP6 tetramer and also expressed intestinal homing receptors. Circulating RV-specific CD4 T cells represent a unique subset that expresses intestinal homing receptors.