1 INTRODUCTION
Acute gastroenteritis (AGE) has been identified as the second leading
cause of death in children <5 years of age, causing
approximately 500,000 deaths annually worldwide 1.
Group A rotavirus (RVA) is the most common cause of AGE in young
children especially under five years of age worldwide2,3. As the main pathogen of AGE, RVA infection and
death occur in all countries worldwide, but mainly in developing
countries 4,5. Based on the Global Burden of Disease
2019 Study (GBD 2019), RVA caused a higher death burden in African,
Oceanian, and South Asian countries in the past three decades6.
Rotavirus was first discovered in 1973 by Bishop and her colleagues in
duodenal biopsies of children with AGE 7. Rotavirus is
a non-enveloped RNA virus of the family Reoviridae in the
subfamily Sedoreovirinae , belonging to the genusRotavirus , with a spherical shape and size of 70 nm. It consists
of a genome of 11 segments of double-stranded RNA (dsRNA) surrounded by
a three-layered icosahedral protein envelope 8. The
genome segments encode six structural viral proteins (VP1-4, VP6 and
VP7) and six non-structural proteins (NSP1-5/6). The two outer capsid
proteins, VP7 (glycoprotein) and VP4 (protease-sensitive protein)
contain neutralizing epitopes and induce protective immunity. The middle
layer consists of VP6, while the inner layer is formed by VP2, which
encloses two proteins, VP1 and VP3 5. Based on the
antigenicity of the VP6 protein, ten RV groups (A-J) and two new
tentative groups (K and L) have been documented. RVA are by far the most
important species in the world in clinical and epidemiological terms9-12. RVA is further subdivided into G and P genotypes
based on VP7 and VP4, respectively 8. Currently, about
42 G genotypes and 58 P genotypes have been reported to the Rotavirus
Classification Working Group (RCWG)
(https://rega.kuleuven.be/cev/viralmetagenomics/virus-classification/rcwg)13.
Among these, several genotype combinations, including G1P[8],
G2P[4], G3P[8], G4P[8], G9P[8] and G12P[8], together
account for an estimated 90-95% of all RVA infections worldwide8,14-16. In contrast to high-income countries, there
is a wide diversity of RVA strains in African countries, where atypical
RVA, including the G1P[4], G1P[6], G8P[4], G8P[8] and
G6P[6] genotypes, are also commonly characterized8.
Vaccination is considered the primary public health approach to control
RVA infection and reduce associated morbidity and mortality3,17-19. Currently, two live-attenuated vaccines,
monovalent Rotarix and pentavalent RotaTaq, are available for global
use.
Two Indian-manufactured vaccines, monovalent Rotavac and pentavalent
Rotasiil, were recently prequalified by WHO in 201820. In China, two RVA vaccines have been licensed for
the Chinese market: Lanzhou lamb RVA vaccine (LLR) consisting of RVA
serotype G10P[12] (Lanzhou Institute of Biological Products)
licensed in 2001, and RotaTeq developed from the bovine WC3 strain
reassorted with human strains G1-G4 and P[8] (Merck) licensed in
2018 21. However, most children in China do not
receive RVA vaccination in time due to the high additional cost of RVA
vaccination 18. Given the diversity of RVA genotypes
and the variety of RVA vaccines, long-term and continuous surveillance
of the epidemiology of RVA is essential to provide implications to
health authorities on suitable policies for RVA vaccination in children.
In Shanghai, studies on RVA infection in children with AGE during 2020
to 2022 were lacking 22. To better understand the role
of RVA in children younger than 16 years with AGE in Shanghai, we
determined the age distribution, gender distribution, seasonal pattern
and genotypic distribution of RVA and updated the profiles of RVA
genotypes from May 2020 to December 2022.