Mouse infection models for space flight immunology.

Several immunological processes can be affected by space flight. However, there is little evidence to suggest that flight-induced immunological deficits lead to illness. Therefore, one of our goals has been to define models to examine host resistance during space flight.

Large granular lymphocytosis, lymphocyte subset inversion, thrombocytopenia, dysproteinemia, and positive Ehrlichia serology in a dog.

A 7-year-old, mixed-breed dog was presented for evaluation of a possible lymphocytic leukemia. Results of laboratory testing included thrombocytopenia, large granular lymphocytosis, inverted CD4:CD8 ratio, hyperglobulinemia, and hypoalbuminemia. Results of a tick-borne disease panel indicated a positive immunoglobulin G serum titer (1:2,048) to Ehrlichia canis, supporting exposure to this organism.

Molecular heterogeneity of Ehrlichia chaffeensis isolates determined by sequence analysis of the 28-kilodalton outer membrane protein genes and other regions of the genome.

Ehrlichia chaffeensis, a tick-transmitted rickettsial agent, is responsible for human monocytic ehrlichiosis (HME). In this study, we genetically mapped 10 isolates obtained from HME patients. Sequence analysis of the 28-kDa outer membrane protein (OMP) multigene locus spanning 6 of the 22 tandemly arranged genes identified three distinct genetic groups with shared homology among isolates within each group.

Persistent Ehrlichia chaffeensis infection occurs in the absence of functional major histocompatibility complex class II genes.

Human monocytic ehrlichiosis is an emerging tick-borne disease caused by the rickettsia Ehrlichia chaffeensis. We investigated the impact of two genes that control macrophage and T-cell function on murine resistance to E. chaffeensis.