Loop-mediated Isothermal Amplification for the Rapid Detection of Genogroup I and Genogroup II Noroviruses

Introduction: Human norovirus (NoV) was identified as one of the major foodborne viruses causing acute viral gastroenteritis. Highly specific and sensitive LAMP technique for NoVs should be developed because RT-PCR or real-time RT-PCR performed in lab is limited to apply for on-site detection.

Purpose: This study aimed to develop the rapid and reliable LAMP for detecting NoV genogroup I (GI) and genogroup II (GII).

Methods: Twenty set of LAMP primer for NoV GI and 24 set for NoV GII were designed in highly conserved region that obtained from aligned sequence of each 30 NoV GI and GII NoVs strains. The sensitivity and sensitivity of LAMP primers for NoV GI and NoV GII were compared with semi-nested RT-PCR and real-time RT-PCR reported in previous study.

Results: For NoV GI, both LAMP and real-time RT-PCR could detect as low as 1000 copy of NoV GI RNA. The sensitivity of semi-nested RT-PCR for NoV GI was 10 times higher than those of LAMP and real-time RT-PCR. For NoV GII, semi-nested RT-PCR, real-time RT-PCR, and LAMP could detect as low as 100 copy of NoV GII RNA. In specificity test, LAMP detected only NoV GI and GII but not hepatitis A virus, Hepatitis E virus, rotavirus, adenovirus.

Significance:  As one-step LAMP in this study detected NoV GI and NoV GII reliably, this technique could be used in field-testing.