Assessment of real-time PCR assays with fluorescent-antibody assays for analysis of respiratory computer virus infections in children. transcription-PCR (RT-PCR) is the most widely reported test (9, 15). Direct immunofluorescence (DFA) staining of medical specimens, with results available within 2 to 4 h, is commonly used in medical virology laboratories for the quick analysis of respiratory viruses (9, 10, 15). In this study, we evaluated a commercial monoclonal antibody reagent to HMPV for its power in the quick analysis of HMPV illness (Light Diagnostics, Chemicon International [right now portion of Millipore], Temecula, CA). Respiratory samples submitted to the Medical Virology Laboratory for respiratory computer virus screening from February through May 2007, the peak HMPV time of year in Connecticut, were used (4). Cytospin-prepared slides were fixed in acetone and stained with SimulFluor respiratory display reagent (Chemicon International, Temecula, CA) as previously explained (10). Excess samples from children 5 years of age testing negative from the respiratory display were selected. An extra slip was stained for HMPV on the day of receipt, prior to RT-PCR testing. Additional samples from older individuals were included when HMPV screening was requested. HMPV DFA results were not reported, since the reagent was regarded as a developmental device at the time of the study. For RT-PCR, 200 l was placed in lysis buffer and stored at ?70C until tested, usually within 1 to 7 days. RNA was extracted using the NucliSens EasyMag extraction system (bioMrieux, Durham, NC). The real-time TaqMan RT-PCR assay targeted the HMPV fusion protein gene as previously explained (11). Two hundred nasopharyngeal (NP) swabs (MicroTest M4 medium; Remel, Lenexa, KS) and 2 bronchoalveolar lavage samples were tested; 190 samples were from children less than 5 years old, 5 were from older children, and 7 were from adults. Forty-eight (23.8%) were positive for HMPV by RT-PCR, and 41 of these were positive for HMPV by cytospin-enhanced DFA (Table ?(Table1).1). Forty-two (87.5%) of the 48 positives were from children 2 years old. One adult on steroid therapy was positive by RT-PCR and DFA. One PCR-negative sample was go through as showing one DFA-positive cell. On rereading, one DFA-positive cell was again observed; however, staining of a second slide from this sample was negative. For the purposes of the study, the RT-PCR result was regarded as the true result and the DFA result was regarded as false positive. Therefore, DFA experienced a level of sensitivity of 85.4%, a specificity of 99.4%, a positive predictive value of 97.6%, and a negative predictive value of 95.7%. The variations between Ginsenoside Rd the results for cytospin-enhanced DFA and RT-PCR were not statistically significant (McNemar’s test; = 0.0771). DFA staining of respiratory epithelial cells was bright, speckled, and predominantly cytoplasmic, with essentially no background staining (Fig. ?(Fig.1).1). Rabbit Polyclonal to BTK (phospho-Tyr223) Due to the selection Ginsenoside Rd of samples that were respiratory display DFA negative, the specificity of the Light Diagnostics HMPV reagent was not fully evaluated. However, three samples that were RSV positive and one that was influenza computer virus A positive by DFA were tested for HMPV, because HMPV was requested. All four were negative with the HMPV DFA reagent, and no nonspecific staining was observed. Open in a separate windows FIG. 1. Examples of ciliated columnar respiratory epithelial cells from individuals’ samples stained with Light Diagnostics HMPV DFA reagent. Staining is definitely bright, apple green, speckled, and predominantly cytoplasmic. Nonspecific background staining is definitely negligible. TABLE 1. Assessment of Ginsenoside Rd Light Diagnostics HMPV direct immunofluorescence reagent and HMPV real-time TaqMan RT-PCR= 0.0771). Even though PCR was not performed like a quantitative assay, the cycle threshold (ideals indicating higher computer virus titers. The 41 DFA-positive samples experienced TaqMan RT-PCR results with ideals of 19.13 to 35.81, having a median of 26.53. The seven RT-PCR positive but DFA-negative samples had ideals of 31.55 to 39.23, having a median of 36.18 (Fig. ?(Fig.22). Open in a separate windows FIG. 2. ideals relating to HMPV DFA results for 48 samples positive by TaqMan RT-PCR. The 41 samples positive by HMPV DFA experienced a median () value of 26.53 (range, 19.13 to 35.81), whereas the 7 samples negative by HMPV DFA had a median () value of 36.18 (range, 31.55 to 39.23). Reviews of immunofluorescence for discovering HMPV in scientific examples are limited. Our lab previously examined an anti-HMPV monoclonal antibody (MAb-8) created on the CDC within an.
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