Whole-genome characterization of common rotavirus strains circulating in Vellore, India from 2002 to 2017: emergence of non-classical genomic constellations

14 years of rotavirus A surveillance: unusual dominance of equine-like G3P[8] genotype with DS-1-like genotype constellation after the pandemic, Belgium, 2009 to 2023

IntroductionDespite vaccine availability, rotavirus persists as a leading cause of gastroenteritis in children younger than 5 years.AimWe aimed to evaluate temporal changes in rotavirus epidemiology in Belgium between 2009 and 2023, including the period of the COVID-19 pandemic.MethodsWe collected 8,024 rotavirus-positive stool samples throughout Belgium. For 6,352 samples, we determined the G and/or P genotypes through sequencing of the genes encoding the outer capsid proteins VP7 and VP4.ResultsBefore the COVID-19pandemic, we received on average 622 samples per rotavirus epidemiological year, which decreased to 114 and 111 samples during the two pandemic rotavirus epidemiological years, followed by a peak of 1,048 samples in the first post-pandemic year. Notably, the proportion of cases in the age group 2-5-years increased from 20.3% before to 33% after the pandemic (p < 0.001). Over the 14-year study period, the most common genotypes were G2P[4], G3P[8] and G9P[8]. Post-pandemic data show an unusually strong dominance of the equine-like G3P[8] genotype which carried a DS-1-like genotype constellation in the period 2021 to 2023. Additionally, vaccinated individuals were significantly overrepresented among patients infected with the equine-like VP7 carrying G3P[8] rotavirus compared with other genotypes, including typical human VP7 G3P[8].ConclusionDespite the presence of typical yearly genotype fluctuations, several epidemiological changes were associated with the COVID-19 pandemic, including the unusual dominance of an emerging rotavirus strain against which current vaccines may be less effective. It is essential to closely monitor this strain to determine if the phenomenon is temporary.

Engineering human/simian rotavirus VP7 reassortants in the absence of UTR sequence information

Recently developed plasmid-based reverse genetics systems for rotavirus A (RVA) enable rapid engineering of reassortants carrying human RVA antigens. However, complete genome segment sequences are required for successful generation of such reassortants, and sequencing of the untranslated regions (UTRs) of field strains is often not accomplished. To address this problem, we established a system that permits the generation of reassortants using only the open reading frame (ORF) nucleotide sequence information. Plasmids containing the VP7-ORF nucleotide sequence of six human RVA field strains (genotypes G2, G5, G8, G9, G12 and G29) derived from GenBank and flanked by the UTR sequences of simian RVA strain SA11 were constructed. Using these plasmids, four VP7 (G2, G5, G9 and G12) reassortants in an SA11 backbone were successfully generated. In contrast, the G8 and G29 reassortants were not viable. BLASTp search of the G8 and G29 sequences revealed an unusual amino acid substitution in each sequence, which was not present in related field strains. Site-directed reversion of the corresponding C656T mutation in G8 led to effective rescue of reassortant virus. However, reverting the G84C mutation in G29 did not result in replicating virus. The results suggest that most human RVA VP7 UTRs can be substituted with simian RVA UTRs. However, generation of reassortants might be impeded by potential sequencing errors or intrinsic reassortment limitations. The established system could help to broaden the antigenic repertoire for rapid engineering of potential novel RVA vaccine strains. KEY POINTS: • Generation of diverse rotavirus vaccine strains is impeded by missing UTR sequences. • UTRs from SA11 can be used instead of missing UTR sequences from field strains. • Human RVA reassortants of genotypes G2, G5, G8, G9, G12 were successfully rescued.

Exploring viral diversity and metagenomics in livestock: insights into disease emergence and spillover risks in cattle

Cattle have a significant impact on human societies in terms of both economics and health. Viral infections pose a relevant problem as they directly or indirectly disrupt the balance within cattle populations. This has negative consequences at the economic level for producers and territories, and also jeopardizes human health through the transmission of zoonotic diseases that can escalate into outbreaks or pandemics. To establish prevention strategies and control measures at various levels (animal, farm, region, or global), it is crucial to identify the viral agents present in animals. Various techniques, including virus isolation, serological tests, and molecular techniques like PCR, are typically employed for this purpose. However, these techniques have two major drawbacks: they are ineffective for non-culturable viruses, and they only detect a small fraction of the viruses present. In contrast, metagenomics offers a promising approach by providing a comprehensive and unbiased analysis for detecting all viruses in a given sample. It has the potential to identify rare or novel infectious agents promptly and establish a baseline of healthy animals. Nevertheless, the routine application of viral metagenomics for epidemiological surveillance and diagnostics faces challenges related to socioeconomic variables, such as resource availability and space dedicated to metagenomics, as well as the lack of standardized protocols and resulting heterogeneity in presenting results. This review aims to provide an overview of the current knowledge and prospects for using viral metagenomics to detect and identify viruses in cattle raised for livestock, while discussing the epidemiological and clinical implications.

Whole-Genome Characterization of Rotavirus G9P[6] and G9P[4] Strains That Emerged after Rotavirus Vaccine Introduction in Mozambique

Mozambique introduced the Rotarix® vaccine into the National Immunization Program in September 2015. Following vaccine introduction, rotavirus A (RVA) genotypes, G9P[4] and G9P[6], were detected for the first time since rotavirus surveillance programs were implemented in the country. To understand the emergence of these strains, the whole genomes of 47 ELISA RVA positive strains detected between 2015 and 2018 were characterized using an Illumina MiSeq-based sequencing pipeline. Of the 29 G9 strains characterized, 14 exhibited a typical Wa-like genome constellation and 15 a DS-1-like genome constellation. Mostly, the G9P[4] and G9P[6] strains clustered consistently for most of the genome segments, except the G- and P-genotypes. For the G9 genotype, the strains formed three different conserved clades, separated by the P type (P[4], P[6] and P[8]), suggesting different origins for this genotype. Analysis of the VP6-encoding gene revealed that seven G9P[6] strains clustered close to antelope and bovine strains. A rare E6 NSP4 genotype was detected for strain RVA/Human-wt/MOZ/HCN1595/2017/G9P[4] and a genetically distinct lineage IV or OP354-like P[8] was identified for RVA/Human-wt/MOZ/HGJM0644/2015/G9P[8] strain. These results highlight the need for genomic surveillance of RVA strains detected in Mozambique and the importance of following a One Health approach to identify and characterize potential zoonotic strains causing acute gastroenteritis in Mozambican children.

Human transmission and outbreaks of feline-like G6 rotavirus revealed with whole-genome analysis of G6P[9] feline rotavirus

Group A rotaviruses (RVAs) are generally highly species-specific; however, some strains infect across species. Feline RVAs sporadically infect humans, causing gastroenteritis. In 2012 and 2013, rectal swab samples were collected from 61 asymptomatic shelter cats at a public health center in Mie Prefecture, Japan, to investigate the presence of RVA and any association with human infections. The analysis identified G6P[9] strains in three cats and G3P[9] strains in two cats, although no feline RVA sequence data were available for the former. A whole-genome analysis of these G6P[9] strains identified the genotype constellation G6-P[9]-I2-R2-C2-M2-A3-N2-T3-E3-H3. The nucleotide identity among these G6P[9] strains exceeded 99.5% across all 11 gene segments, indicating the circulation of this G6P[9] strain among cats. Notably, strain RVA/Human-wt/JPN/KF17/2010/G6P[9], previously detected in a 3-year-old child with gastroenteritis, shares high nucleotide identity (>98%) with Mie20120017f, the representative G6P[9] strain in this study, across all 11 gene segments, confirming feline RVA infection and symptomatic presentation in this child. The VP7 gene of strain Mie20120017f also shares high nucleotide identity with other sporadically reported G6 RVA strains in humans. This suggests that feline-origin G6 strains as the probable source of these sporadic G6 RVA strains causing gastroenteritis in humans globally. Moreover, a feline-like human G6P[8] strain circulating in Brazil in 2022 was identified, emphasizing the importance of ongoing surveillance to monitor potential global human outbreaks of RVA.