HAstV-1 was also identified as the predominant serotype in China . Wei et al.  developed a one-step, real-time reverse-transcription LAMP (rRT-LAMP) method with a turbidimeter targeting the 5’ end of the capsid gene for rapid and
quantitative detection of HAstV-1 from stool specimens. In our study, RT-LAMP with HNB for specific, rapid and sensitive detection of HAstV-1 in water samples was developed. To our knowledge, this is the first report of the application of RT-LAMP with HNB to HAstV-1. Results Optimized LAMP reaction The LAMP reaction was performed using plasmid DNA as template selleck compound to determine the optimal reaction conditions. The optimal concentrations of betaine and Mg2+ ion in the LAMP reactions were 1 mmol·L-1
and 4 mmol·L-1, respectively (data not shown). The amplicon was formed at 63, 64, 65 and 66°C, with the optimal temperature for product detection being 65°C. Thus, 65°C was used as the optimum temperature for the following assays. Although we could detect well-formed bands at 60 min, the reaction time was extended to 90 min to ensure positive detection of lower concentration templates in the system. Naked-eye observation of LAMP products using HNB The LAMP reaction was incubated in a conventional water bath at 65°C for 90 min, followed by heating at 80°C for 2 min to terminate the reaction. The ability to detect astrovirus LAMP products using HNB was examined. Positive amplification was indicated by a color change from violet to sky blue, as shown in Figure 1B, and verified Vorinostat mouse by agarose gel electrophoresis (Figure 1A) and white precipitates (Figure 1C). The positive color (sky blue) was only observed with the reference virus, whereas none of the control viruses showed a color change. Figure 1 Detection of LAMP products by observation of white turbidity and the color of the reaction mixture. (A) LAMP detection of astrovirus by electrophoresis; (B) Color reaction with HNB; (C) White precipitates M: Marker; CK: heptaminol Blank control;
S: Astrovirus. Specificity and sensitivity of the LAMP assay The sizes of the LAMP fragments digested with the BMN 673 clinical trial Restriction enzyme, EcoN1, were analyzed by electrophoresis, and the results showed agreement with the predicted sizes of 84 and 135 bp (Figure 2A). The specificity of the LAMP assays was examined with two other enteric viruses: rotavirus and norovirus. The results of the LAMP assay were positive for astrovirus and negative for rotavirus and norovirus (Figure 2B). Figure 2 Specificity of astrovirus detection using the LAMP assay. (A) Restriction analysis; (B) Specificity analysis of cross-reaction by electrophoresis M: Marker; CK: Blank control; S: LAMP products after digestion with EcoNI 1: Astrovirus; 2: Rotavirus; 3: Norovirus. The reaction was tested using 5 μL of 10-fold serial dilutions of in vitro RNA transcripts (3.6×109 copies·μL-1) and compared with PCR assays. The detection limit of LAMP using astrovirus RNA was 3.