Spread of genetically similar noroviruses in Bangkok, Thailand, through symptomatic and asymptomatic individuals

An unusual diarrheal outbreak in the community in Eastern Thailand caused by Norovirus GII.3[P25]

BACKGROUND

Sentinel laboratory surveillance for diarrheal disease determined norovirus to be the most common cause of non-bacterial gastroenteritis in people during the COVID-19 pandemic in Thailand. An increase in patients presenting with diarrhea and vomiting in hospitals across Chanthaburi province between December 2021 and January 2022 led to the need for the identification of viral pathogens that may be responsible for the outbreak.

METHODS

Fecal samples (rectal swabs or stool) from 93 patients, of which 65 patients were collected during the December 2021 to January 2022 outbreak, were collected and screened for viral infection by real-time RT-PCR. Positive samples for norovirus GII were then genotyped by targeted amplification and sequencing of partial polymerase and capsid genes. Full genome sequencing was performed from the predominant strain, GII.3[P25].

RESULTS

Norovirus was the most common virus detected in human fecal samples in this study. 39 of 65 outbreak samples (60%) and 3 of 28 (10%) non-outbreak samples were positive for norovirus genogroup II. One was positive for rotavirus, and one indicated co-infection with rotavirus and norovirus genogroups I and II. Nucleotide sequences of VP1 and RdRp gene were successfully obtained from 28 of 39 positive norovirus GII and used for dual-typing; 25/28 (89.3%) were GII.3, and 24/28 (85.7) were GII.P25, respectively. Norovirus GII.3[P25] was the predominant strain responsible for this outbreak. The full genome sequence of norovirus GII.3[P25] from our study is the first reported in Thailand and has 98.62% and 98.57% similarity to norovirus found in China in 2021 and the USA in 2022, respectively. We further demonstrate the presence of multiple co-circulating norovirus genotypes, including GII.21[P21], GII.17[P17], GII.3[P12] and GII.4[P31] in our study.

CONCLUSIONS

An unusual diarrhea outbreak was found in December 2021 in eastern Thailand. Norovirus strain GII.3[P25] was the cause of the outbreak and was first detected in Thailand. The positive rate during GII.3[P25] outbreak was six times higher than sporadic cases (GII.4), and, atypically, adults were the primary infected population rather than children.

Biological Activities and Nanoparticle Synthesis of Dioscorea bulbifera and its Mechanistic Action - An Extensive Review

BACKGROUND

Dioscorea bulbifera is commonly known as air potato present in the tropical and subtropical regions. It is a perennial climber traditionally used for various therapeutic purposes by traditional healers. This review explores various medicinal uses of D. bulbifera and its active ingredients, as well as describes its nanoparticle synthesis for medical applications.

METHODS

The Google Scholar search engine was used to conduct this comprehensive review along with the databases of the following publishers: Elsevier, Springer, Taylor and Francis, Bentham, and PubMed.

DISCUSSION

D. bulbifera contains several bioactive compounds that are responsible for its pharmacological properties, such as antioxidant, anti-inflammatory, neuroprotective, anticancer, and antidiabetic properties. It is also used as a nutritive functional food. D. bulbifera-mediated nanoparticle synthesis has been established by the scientific communities for various medicinal applications.

CONCLUSION

D. bulbifera contains numerous active ingredients, including diosbulbins, bafoudiosbulbin, β-sitosterol, diosgenin, dioscin, pennogenin, myricetin, quercetin, and stigmasterols with numerous biological activities. In addition, it has a vital role in synthesizing nanoparticles with good pharmacological applications, especially in drug delivery systems. However, its potential characteristic features and functional properties of the active molecules present in this tuber need to be further explored in clinical trials. We suggest that using this edible tuber, we may formulate the valueadded food with good medicinal applications.

Emergent variant modeling of the serological repertoire to norovirus in young children

Human norovirus is the leading cause of acute gastroenteritis. Young children and the elderly bear the greatest burden of disease, representing more than 200,000 deaths annually. Infection prevalence peaks at younger than 2 years and is driven by novel GII.4 variants that emerge and spread globally. Using a surrogate neutralization assay, we characterize the evolution of the serological neutralizing antibody (nAb) landscape in young children as they transition between sequential GII.4 pandemic variants. Following upsurge of the replacement variant, antigenic cartography illustrates remodeling of the nAb landscape to the new variant accompanied by improved nAb titer. However, nAb relative avidity remains focused on the preceding variant. These data support immune imprinting as a mechanism of immune evasion and GII.4 virus persistence across a population. Understanding the complexities of immunity to rapidly evolving and co-circulating viral variants, like those of norovirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV2), and dengue viruses, will fundamentally inform vaccine design for emerging pathogens.