Aim: Determine the in vivo effect of Pneumocystis carinii pneumonia (PCP) on: (a) the titre of infectious virus circulating in blood; and (b) the chemokine co-receptor usage of these viruses.
Patients and methods: A longitudinal study of 62 patients over 8 years. The results for PCP were compared with those for disseminated cytomegalovirus (CMV) and acute herpes simplex virus type 1 infections (HSV). Blood was collected every 3-4 months when patients were well, and again when they were acutely ill. A tissue culture based PHA/IL-2 induced HIV replication assay was used to determine the frequency of circulating cells in blood carrying infectious forms of HIV-1. Viral isolates were phenotyped using U87 cells transfected with CD4 and a chemokine co-receptor.
Results: There were 29 cases of PCP, 18 cases of HSV and 11 cases of CMV. A significant increase in the viral replication assay was seen during severe PCP but not during HSV or CMV infections. The number of chemokine co-receptors being used by HIV-1 increased during severe PCP to include CXCR4 and CCR3 in three of six patients from whom viruses were available for detailed study.
Conclusions: Severe PCP can increase the number of PBMN cells containing integrated, replication competent, infectious forms of HIV-1 circulating in blood. The expanded chemokine co-receptor tropism of these viral isolates could promote the dissemination of HIV-1 from lymphoid to non-lymphoid organs and explain the poor prognosis of patients who develop severe PCP.
Copyright 2001 The British Infection Society.