Development and evaluation of a quantitative assay detecting cytomegalovirus transcripts for preemptive therapy in allogeneic hematopoietic stem cell transplant recipients.

Successful preemptive therapy for cytomegalovirus (CMV) infection after hematopoietic stem cell transplantation (HSCT) depends on the availability of a rapid and sensitive assay to guide early treatment. Currently, the antigenemia assay and the quantitative real-time PCR (qPCR) assay are widely used for this purpose, but they have distinctive concerns. This study aimed to develop and evaluate a novel CMV diagnostic test based on transcription-reverse transcription concerted reaction (TRC), an RNA-detecting technology. The CMV-TRC assay detected CMV ß2.7 transcripts within 10 min over a five-log range. Among a total of 219 samples obtained from 24 allogeneic HSCT recipients, samples detected as positive by the CMV-TRC assay showed a relatively strong correlation with those detected as positive by the qPCR assay and the antigenemia assay. The CMV-TRC assay showed higher sensitivity (77.7%) than the antigenemia assay (68.1%) and detected the first and recurrent episodes of active CMV infection in HSCT patients significantly earlier than the antigenemia assay (P < 0.001). Although the CMV-TRC assay (87.8%) showed low sensitivity compared to the qPCR assay (96.3%), the performance of the CMV-TRC assay was equivalent to that of the qPCR assay in detecting the appearance of active CMV infection episodes (P < 0.092) or rather superior in detecting the clearance of episodes (P < 0.001). The CMV-TRC assay with several advantages may be useful for guiding preemptive anti-CMV therapy in HSCT recipients.

Dectin-2-dependent NKT cell activation and serotype-specific antibody production in mice immunized with pneumococcal polysaccharide vaccine.

Although thymus-independent type 2 antigens generally do not undergo Ig class switching from IgM to IgG, pneumococcal polysaccharide vaccine (PPV) induces the production of serotype-specific IgG. How this happens remains unclear, however. In the present study, PPV immunization induced production of IgG as well as IgM specific for a serotype 3-pneumococcal polysaccharide in the sera of wild-type (WT) mice, but this phenomenon was significantly reduced in Dectin-2 knockout (KO) mice. Immunization with PPV caused IL-12p40 production in WT mice, but this response was significantly reduced in Dectin-2KO mice. Likewise, immunization with PPV activated natural killer T (NKT) cells in WT mice but not in Dectin-2KO mice. Furthermore, administration of α-galactosylceramide, recombinant (r)IL-12 or rIFN-γ improved the reduced IgG levels in Dectin-2KO mice, and treatment with neutralizing anti-IFN-γ mAb resulted in the reduction of IgG synthesis in PPV-immunized WT mice. Transfer of spleen cells from PPV-immunized WT mice conferred protection against pneumococcal infection on recipient mice, whereas this effect was cancelled when the transferred spleen cells were harvested from PPV-immunized Dectin-2KO mice. These results suggest that the detection of PPV antigens via Dectin-2 triggers IL-12 production, which induces IFN-γ synthesis by NKT cells and subsequently the production of serotype-specific IgG.