Abstract
A preliminary study was carried out in order to evaluate a reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) assay for detecting Noroviruses (NoV) RNA surrogates as external standard for NoV.The detection limit of the NoV RT-LAMP assay was observed to be 22 copies/μL. This RT-LAMP assay sensitivity was comparablewith the quantitative reverse transcriptase-Polymerase Chain Reaction (PCR) and shown to be 10-fold more sensitive than end-point conventional reverse transcriptase-PCR (RT-PCR). The NoV RT-LAMP assay showed high specificity to NoV targeted gene when specificity test was completed with no cross-reactivity with other 17 environmental strains. The assay also was performed with 11 spiked recreational stream water randomly picked from two recreational areas in Hulu Langat Malaysia, Sg. Tekala and Sg. Gabai. The RT-LAMP assay is simpler compared to the conventional PCR and real-time PCR, which in optimum isothermal temperature of 63°C, the amplification can be completed in 40 minutes. Results of spiked recreational stream water samples suggested that the NoV RT-LAMP assay can be used as monitoring tool for NoV surveillance in recreational stream water.
Highlights
There are not many surveillance of NoV in Malaysia have been carried out in water and environment area except very few studies had been performed in food application[1,2]
The lack of information could be contributed to misdiagnose of severe diarrhea symptoms of NoV to other gastroenteritis bacterial such as Shigellasp. and Escherichia coli and other enteric viruses like Rotavirus and Adenovirus [3].It is suggested that the infection of NoV occurred from the activities of swimming, canoeing or other recreational activities relating
The requirement of 18 to 24 hours of virus incubation postexposure prior to issue advisory on infectivity may increased the greater risk of infection[8,9]. Another drawback of using fecal indicator bacteria (FIB) as indicator is that these bacteria has been reported to continuously grow in the environment, leads to a bias in assessment especially in tropical weather like Malaysia[10,11,12]. Human enteric viruses such as enteroviruses, NoV and adenoviruses which directly associated with human diseases found to be more reliable indicators for fecal contaminated water [13,14].These enteric viruses have the ability to survive for longer period of time and reflect their existence in real number since they cannot replicates without permissive host organism in water [13,15]
Summary
There are not many surveillance of NoV in Malaysia have been carried out in water and environment area except very few studies had been performed in food application[1,2]. Fecal indicator bacteria (FIB) such as E.coli and enterococci has been widely used as standard procedure to evaluate fecal borne pathogen contamination in water This technique is being used for water quality criteria [7], it has limitation in protecting the public from recreational waterborne disease especially viruses infection. The requirement of 18 to 24 hours of virus incubation postexposure prior to issue advisory on infectivity may increased the greater risk of infection[8,9] Another drawback of using FIB as indicator is that these bacteria has been reported to continuously grow in the environment, leads to a bias in assessment especially in tropical weather like Malaysia[10,11,12]. Human enteric viruses such as enteroviruses, NoV and adenoviruses which directly associated with human diseases found to be more reliable indicators for fecal contaminated water [13,14].These enteric viruses have the ability to survive for longer period of time and reflect their existence in real number since they cannot replicates without permissive host organism in water [13,15]
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