ABSTRACT
Introduction: Norovirus (NoV) is one of the most important agents responsible for viral acute gastroenteritis, among which GII.4 NoV is the predominant strain worldwide, and GII.17 NoV surpassed GII.4 in some epidemic seasons. Rapid and accurate gene recognition is essential for a timely response to NoV outbreaks. Methods: In the present study, the highly conserved regions of GII.4 and GII.17 NoVs were identified in the junction of open reading frame (ORF) 1 and ORF2 and then amplified by isothermal recombinase-aided amplification (RAA), followed by the cleavage of CRISPR-Cas13a with screened CRISPR RNAs (crRNAs) and RAA primers. The entire detection procedure could be completed within 40 min using a thermostat, and the results could be read out by the naked eye under a portable blue light transilluminator. Discussion: The assay showed a high sensitivity of 97.96% and a high specificity of 100.0%. It offered a low limit of detection (LOD) of 2.5×100 copies/reaction and a coincidence rate of 96.75% in 71 clinical fecal samples. Overall, rapid and inexpensive detection of GII.4/GII.17 NoVs was established, which makes it possible to be used in areas with limited resources, particularly in low-income countries. Furthermore, it will contribute to assessing transmission risks and implementing control measures for GII.4/GII.17 NoVs, making healthcare more accessible worldwide.
ABSTRACT
Noroviruses (NoVs) are the leading viral pathogens globally causing acute gastroenteritis (AGE) in humans, posing a significant global health threat and economic burden. Recent investigations revealed that human NoVs had been detected in different animals, which raises concerns about whether NoVs are potential zoonotic diseases. This study developed a novel luciferase immunosorbent assay (LISA) to detect GII.6 NoV IgG based on P protein of VP1. The LISA showed high specificity (99.20%) and sensitivity (92.00%) with 4-16 times more sensitivity compared with an ELISA. NoV-LISA was reproducible with human serum regarding the inter- and intra-assay coefficient of variance values. Potential cross-reactivity was also evaluated using mice serum immunized by other antigens, which showed that NoV-LISA could differentiate GII.6 NoV from rotavirus and various genotypes of NoV. Specific GII.6 NoV IgG was widely detected in different domestic and wild animals, including dogs, pigs, bats, rats, and home shrews, with various IgG-positive rates ranging from 2.5 to 74.4%. In conclusion, our newly developed NoV-LISA assay is suitable for NoV-specific IgG detection in humans and animals. The wide distribution of IgG antibodies against human NoV indicates potential zoonotic transmission between humans and animals.
ABSTRACT
Introduction: Herd immunity against norovirus (NoV) is poorly understood in terms of its serological properties and vaccine designs. The precise neutralizing serological features of genotype I (GI) NoV have not been studied. Methods: To expand insights on vaccine design and herd immunity of NoVs, seroprevalence and seroincidence of NoV genotypes GI.2, GI.3, and GI.9 were determined using blockade antibodies based on a 5-year longitudinal serosurveillance among 449 residents in Jidong community. Results: Correlation between human histo-blood group antigens (HBGAs) and GI NoV, and dynamic and persistency of antibodies were also analyzed. Seroprevalence of GI.2, GI.3, and GI.9 NoV were 15.1%-18.0%, 35.0%-38.8%, and 17.6%-22.0%; seroincidences were 10.0, 21.0, and 11.0 per 100.0 person-year from 2014 to 2018, respectively. Blockade antibodies positive to GI.2 and GI.3 NoV were significantly associated with HBGA phenotypes, including blood types A, B (excluding GI.3), and O+; Lewis phenotypes Leb+/Ley+ and Lea+b+/Lex+y+; and secretors. The overall decay rate of anti-GI.2 antibody was -5.9%/year (95% CI: -7.1% to -4.8%/year), which was significantly faster than that of GI.3 [-3.6%/year (95% CI: -4.6% to -2.6%/year)] and GI.9 strains [-4.0%/year (95% CI: -4.7% to -3.3%/year)]. The duration of anti-GI.2, GI.3, and GI.9 NoV antibodies estimated by generalized linear model (GLM) was approximately 2.3, 4.2, and 4.8 years, respectively. Discussion: In conclusion, enhanced community surveillance of GI NoV is needed, and even one-shot vaccine may provide coast-efficient health benefits against GI NoV infection.
