Human metapneumovirus (hMPV), a newly discovered paramyxovirus, has been associated with acute respiratory tract infections (ARIs) ranging from upper ARIs to severe bronchiolitis and pneumonia. Important questions remain on the contribution of hMPV to ARIs and its impact on public health. During the 2001-2002 season, we conducted a collaborative study with four provincial public health laboratories to study the prevalence of this new virus in the Canadian population. A total of 445 specimens were collected from patients of all age groups with ARIs and were tested for the presence of hMPV by reverse transcription-PCR. Of these, 66 (14.8%) tested positive for hMPV. Positive specimens were found in all age groups and in all four provinces studied. Virus activity peaked in February and March. The age range of the patients with hMPV infection was 2 months to 93 years (median age, 25 years), with similar numbers of females (35%) and males (41%). Thirty-three percent (n ‫؍‬ 22) of hMPV-infected patients were hospitalized; of these, 27% (n ‫؍‬ 6) had rhinitis and pneumonia, 23% (n ‫؍‬ 5) had bronchiolitis, and 9% (n ‫؍‬ 2) had bronchitis. The hospitalization rates were significantly higher among patients <5 years of age (P ‫؍‬ 0.0005) and those >50 years of age (P ‫؍‬ 0.0044) than among those 6 to 50 years of age. Phylogenetic analysis of the F gene showed that two hMPV genetic clusters were cocirculating in the 2001-2002 season, and comparison with earlier studies suggests a temporal evolutionary pattern of hMPV isolates. These results provide further evidence of the importance of hMPV in ARIs, particularly in young children and elderly individuals.

We have adapted the Beckman Airfuge air turbine ultracentrifuge and the new EM-90 particle-counting rotor to improve detection by electron microscopy of viruses in clinical specimens. Samples were clarified by centrifugation, pelleted in the EM-90 rotor directly to Formvar-coated copper grids, and stained with 1.5% sodium phosphotungstate. Virus counts and endpoint titrations of serial dilutions of partially purified preparations of poliovirus, SAIl rotavirus, herpes simplex

Fecal samples submitted for virus examination over July 1990 to June 1991 from children < 3 years of age were examined by electron microscopy (EM), virus culture (VC), and enzyme immunoassay [EIA, group-reactive and adenovirus (Ad) 40/41 specific; Cambridge BioScience] to compare the detection rate of adenovirus from pediatric fecal specimens. Ad isolates of serotypes 1-7 grown in HEp-2 or primary rhesus monkey kidney cells were identified by neutralization. Graham 293 cell cultures were used only when specimens were found to be positive for Ad by EM, type-specific Ad40/41 EIA, and for isolates not identified by neutralization. Ads grown in 293 cells were identified by DNA restriction endonuclease analysis. Of the 1187 specimens examined, 105 (9%) were found to be positive for Ad. VC detected 93, while 12 additional positives were detected by EM or EIA. The relative sensitivity of VC, EIA, and EM for the 105 specimens was 89% (93), 45% (47), and 35% (37), respectively. Among the 105 positive specimens, enteric Ad, nonenteric Ad, and untypeable Ad were 28% (29), 65% (68), and 7% (8), respectively. Of 37 EM positives, 62% (23) were enteric Ad; 27% (10) were nonenteric including serotypes 2, 3, 4, 5, 12, and 31, with 4, 1, 1, 2, 1, and 1 isolates of each type positive, respectively; and 11% (4) were detectable only by EM. Five isolates were identified as variant of Ad 2(3), Ad 3(1) and Ad 31(1). Over a 1-year period, a single Ad41 variant strain was the most frequently detected enteric Ad in Winnipeg, Manitoba, Canada.(ABSTRACT TRUNCATED AT 250 WORDS)

A commercial monoclonal antibody enzyme immunoassay for the detection of enteric adenovirus types 40 and 41 (Ad4O and Ad4l) in stool specimens was evaluated. Twenty-one stool specimens from children with gastroenteritis, with adenovirus particles visible by electron microscopy, and reference strains Ad4O Dugan and Ad4l Tak were tested by Ad4O-and Ad4l-specific and adenovirus group-reactive immunoassays. AU stool specimens tested positive in the group-reactive immunoassay. However, only six specimens, containing isolates of Ad4O strain Hovi-X, an Ad4O genomic variant, and Ad4l strain Tak, reacted with the specific immunoassay, besides the reference strains. Fifteen stool specimens determined by restriction analysis to contain a genomic variant of Ad4l were negative by specific immunoassay. The positions of restriction site differences from the prototype strain Ad4l Tak were analyzed, and four mutations were mapped within the hexon gene; two others may occur in the fiber gene. The Ad4l genomic variant not detected by the enteric test is presently the most frequent cause of local adenoviral gastroenteritis. Highly specific monoclonal antibodies can fail to detect genomic variants of enteric adenoviruses, probably because of alteration of external neutralizable epitopes under immunological pressure to vary.

The sensitivity of the counterimmunoelectrophoresis test with NCDV, Wa, and SA-11 rotavirus antisera was 60, 60, and 67%, respectively. The counterimmunoelectrophoresis specificity was greater than 99%, but the low sensitivity is a limiting feature of this test as a first-line immunodiagnostic test for rotavirus detection.