Human Metapneumovirus Infection in Adult Patients after Allogeneic Hemopoietic Stem Cell Transplantation.

The human metapneumovirus (hMPV) has been described as possible cause of respiratory disease in pediatric and adult subjects. There are not, however, data concerning the epidemiology and or the clinical impact of hMPV infection in adults receiving allogeneic hemopoietic stem cell (HSC) transplant. We report the results of a prospective study aimed to asses the incidence of hMPV infection in patients undergoing allogeneic HSC transplant. We analyzed by reverse transcription PCR assay, the presence of hMPV in nasopharingeal aspirate (NPA) collected before transplant and on day 0, +15, +30, +60, +90, +180, +360 from transplant. Detection of hMPV RNA was based on two set primers pair located in the L and N genes. Amplified hMPV RNA was sequenced for genotyping in region N.

Twenty patients with a median age of 37 yrs (range 25–58), receiving allogeneic HSC for hematological disorders (AML 11 pts, ALL 5 pts, MDS 2 pts, NHL and MM 1 pt each), entered the study. Six pts received transplant from an HLA identical sibling and 14 from an unrelated donor (MUD). As preparative regimen, 15 pts had a standard myeloablative conditioning regimen, and 5 received reduced intensity conditioning with Thiotepa and Fludarabine. Acute graft-versus-host-disease prophylaxis consisted of Cyclosporine A and Methotrexate. In 6 pts receiving MUD transplant, in vivo T depletion by ATG was performed. At transplant, all patients were in good performance status and none had signs of active acute respiratory disease. Of 20 patients, four had a prior history of pulmonary infection from agents different from hMPV.

Of 49 NPA samples analyzed so far, 29 (59%) resulted hMPV-positive. Sequence analysis performed in 12 patents detected a virus genotype-A. Of 12 pts in whom 3 or more NPA samples were collected, 9 (45%) resulted positive for hMPV RT-PCR, with persistence of infection for a period ranging from 14 to 84 days. No patient, however, showed clinical signs of respiratory disease. These data indicate an high prevalence and a long persistence of asymptomatic hMPV infection in adults receiving allogeneic HSC transplant.