Host range of chlamydiaphages phiCPAR39 and Chp3.

The host range of phiCPAR39 is limited to four Chlamydophila species: C. abortus, C. caviae, C. pecorum, and C. pneumoniae. Chp3 (a newly discovered bacteriophage isolated from C. pecorum) shares three of these hosts (C. abortus, C. caviae, and C. pecorum) but can additionally infect Chlamydophila felis. The ability to support replication was directly correlated with the binding properties of the respective bacteriophages with their host species. Binding studies also show that phiCPAR39 and Chp3 use different host receptors to infect the same host cells: cell binding is sensitive to proteinase K treatment, confirming that the chlamydiaphage receptors are proteinaceous in nature.

Biological properties and cell tropism of Chp2, a bacteriophage of the obligate intracellular bacterium Chlamydophila abortus.

A number of bacteriophages belonging to the Microviridae have been described infecting chlamydiae. Phylogenetic studies divide the Chlamydiaceae into two distinct genera, Chlamydia and Chlamydophila, containing three and six different species, respectively. In this work we investigated the biological properties and host range of the recently described bacteriophage Chp2 that was originally discovered in Chlamydophila abortus. The obligate intracellular development cycle of chlamydiae has precluded the development of quantitative approaches to assay bacteriophage infectivity. Thus, we prepared hybridomas secreting monoclonal antibodies (monoclonal antibodies 40 and 55) that were specific for Chp2. We demonstrated that Chp2 binds both C. abortus elementary bodies and reticulate bodies in an enzyme-linked immunosorbent assay. Monoclonal antibodies 40 and 55 also detected bacteriophage Chp2 antigens in chlamydia-infected eukaryotic cells. We used these monoclonal antibodies to monitor the ability of Chp2 to infect all nine species of chlamydiae. Chp2 does not infect members of the genus Chlamydia (C. trachomatis, C. suis, or C. muridarum). Chp2 can infect C. abortus, C. felis, and C. pecorum but is unable to infect other members of this genus, including C. caviae and C. pneumoniae, despite the fact that these chlamydial species support the replication of very closely related bacteriophages.

Dipyridamole thallium imaging in patients being considered for vascular procedures.

We routinely performed intravenous dipyridamole thallium imaging and resting radionuclide ventriculography on 190 patients being considered for elective vascular procedures. Patients with thallium redistribution underwent coronary arteriography. Patients in group 1 (n = 78) had clinical evidence of coronary artery disease, and patients in group 2 (n = 112) had no history or electrocardiographic evidence of coronary artery disease. The frequency of thallium redistribution was not significantly different in the two groups (45% in group 1 and 46% in group 2). Coronary arteriography identified severe three-vessel or left main disease in eight patients (10%) in group 1 and 16 patients (14%) in group 2. Selection of patients for dipyridamole thallium imaging prior to vascular reconstruction should be based on whether or not documentation of the extent of coronary artery disease would influence therapy rather than on clinical indicators of coronary disease.