Chantal Ama Agbemabiese

Changes in the distribution of lineage constellations of G2P(4) Rotavirus A strains detected in Japan over 32 years (1980-2011)

Rotavirus A (RVA) is a leading cause of acute gastroenteritis in young children worldwide. Most human RVA strains are classified into three major genotype constellations: Wa-like, DS-1-like and AU-1-like. The evolution of G2P[4] strains possessing the DS-1-like genetic background was described in a few recent studies. However, the strains analyzed in these studies were almost exclusively the ones detected after 2000. In recognition of the scarcity of G2P[4] strains detected before 2000 for which whole genome information was available, this study was undertaken to characterize 19 Japanese G2P[4] strains detected between 1983 and 1990 (14 strains) and between 2001 and 2011 (5 strains), and to compare them with 131 G2P[4] strains from across the world. The Japanese strains along with the strains elsewhere in the world underwent stepwise changes from lineage I to IVa in 5 genes (the VP7, VP4, VP2, NSP1 and NSP5 genes) and from lineage I to V in 6 genes (the VP6, VP1, VP3, NSP2, NSP3 and NSP4 genes). Furthermore, G2P[4] strains detected after 2004 appeared to have undergone further intragenotype reassortment, resulting in the emergence of lineage V in the VP7 gene, and VI and VII in the VP3 and NSP4 genes. The time of the most recent common ancestor (tMRCA) for the emergent lineages VI and VII was estimated to be around the early 2000s. However, the year when the ancestor of the emergent lineages diverged from that of the rest of the lineages in the respective genes preceded the tMRCA 80-90 years. The origin of the emergent lineages is likely to be human RVA strains possessing genotypes other than G2P[4], and not RVA strains of an animal origin. In conclusion, stepwise changes in lineages imparted new genomic constellations to G2P[4] strains, which appears to have contributed to their successful spread across the globe, most notably since 2004.

Molecular epidemiology of Rotavirus A, causing acute gastroenteritis hospitalisations among children in Nha Trang, Vietnam, 2007–2008: Identification of rare G9P[19] and G10P[14] strains

Rotavirus A (RVA) causes acute diarrhea in children as well as animals. As part of a cross‐sectional study of children less than 5 years of age hospitalized for acute diarrhea in Vietnam during a 15‐month period (2007–2008), 322 (43.5%) of 741 fecal specimens contained RVA with 92% either G1P[8] or G3P[8]. This study was undertaken to further characterize strains that remained untypeable to complete the G and P genotypes of the 322 rotavirus‐positive specimens. While 307 (95.3%) strains possessed the common human RVA genotypes: G1P[8] (45.0%), G2P[4] (2.8%), G3P[8] (46.9%), and G9P[8] (0.6%), sequencing of initially untypeable specimens revealed the presence of two unusual strains designated NT0073 and NT0082 possessing G9P[19] and G10P[14], respectively. The genotype constellation of NT0073 (G9‐P[19]‐I5‐R1‐C1‐M1‐A8‐N1‐T7‐E1‐H1) and the phylogenetic trees suggested its origin as a porcine RVA strain causing diarrhea in a 24‐month‐old girl whereas the genotype constellation of NT0082 (G10‐P[14]‐I2‐R2‐C2‐M2‐A3‐N2‐T6‐E2‐H3) and the phylogenetic trees suggested its origin as an RVA strain of artiodactyl origin (such as cattle, sheep and goats) causing diarrhea in a 13‐month‐old boy. This study showed that RVA strains of animal host origin were not necessarily attenuated in humans. A hypothesis may be postulated that P[19] and P[14] VP4 spike proteins helped the virus to replicate in the human intestine but that efficient onward human‐to‐human spread after crossing the host species barrier may require the virus to obtain some additional features as there was no evidence of widespread transmission with the limited sampling performed over the study period. J. Med. Virol. 89:621–631, 2017.

Evolution of DS-1-like G1P[8] double-gene reassortant rotavirus A strains causing gastroenteritis in children in Vietnam in 2012/2013

Rotavirus A (RVA) strains, a leading cause of severe gastroenteritis in children worldwide, commonly possess the Wa or DS-1 genotype constellations. During a hospital-based study conducted in Hanoi, Vietnam, in the 2012-2013 rotavirus season, G1P[8] strains with a virtually identical short RNA migration pattern were detected in 20 (14%) of 141 rotavirus-positive samples. Two representatives of these strains were shown by whole-genome sequencing to be double-gene reassortants possessing the genotype constellation of G1-P[8]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Sequencing and a database search revealed that these Vietnamese G1P[8] double-gene reassortant strains shared an immediate ancestor with a locally circulating G2P[4] strain in all of the inner-capsid and non-structural protein genes, whereas they were more closely related in the VP7 and VP4 genes to a Chinese G1P[8] strain and a Chinese G3P[8] strain, respectively, than to locally circulating G1P[8] strains. Despite the marked similarity between Japanese and Thai G1P[8] double-gene reassortant strains, phylogenetic analysis suggested that the Vietnamese and Japanese/Thai G1P[8] double-gene reassortant strains originated from independent reassortment events. Clinically, children infected with Vietnamese G1P[8] double-gene reassortant strains experienced severe diarrhoea, but it was not more severe than that in children infected with ordinary G1P[8] strains. In conclusion, Vietnamese G1P[8] double-gene reassortant strains originated from a locally circulating G2P[4] strain and caused severe diarrhoea, but there was no evidence of increased virulence.

Whole genomic constellation of the first human G8 rotavirus strain detected in Japan.

Human G8 Rotavirus A (RVA) strains are commonly detected in Africa but are rarely detected in Japan and elsewhere in the world. In this study, the whole genome sequence of the first human G8 RVA strain designated AU109 isolated in a child with acute gastroenteritis in 1994 was determined in order to understand how the strain was generated including the host species origin of its genes. The genotype constellation of AU109 was G8-P[4]-I2-R2-C2-M2-A2-N2-T2-E2-H2. Phylogenetic analyses of the 11 genome segments revealed that its VP7 and VP1 genes were closely related to those of a Hungarian human G8P[14] RVA strain and these genes shared the most recent common ancestors in 1988 and 1982, respectively. AU109 possessed an NSP2 gene closely related to those of Chinese sheep and goat RVA strains. The remaining eight genome segments were closely related to Japanese human G2P[4] strains which circulated around 1985-1990. Bayesian evolutionary analyses revealed that the NSP2 gene of AU109 and those of the Chinese sheep and goat RVA strains diverged from a common ancestor around 1937. In conclusion, AU109 was generated through genetic reassortment event where Japanese DS-1-like G2P[4] strains circulating around 1985-1990 obtained the VP7, VP1 and NSP2 genes from unknown ruminant G8 RVA strains. These observations highlight the need for comprehensive examination of the whole genomes of RVA strains of less explored host species.

Whole genome characterisation of a porcine-like human reassortant G26P[19] Rotavirus A strain detected in a child hospitalised for diarrhoea in Nepal, 2007

A rare G26 Rotavirus A strain RVA/Human-wt/NPL/07N1760/2007/G26P[19] was detected in a child hospitalised for acute diarrhoea in Kathmandu, Nepal. The complete genome of 07N1760 was determined in order to explore its evolutionary history as well as examine its relationship to a Vietnamese strain RVA/Human-wt/VNM/30378/2009/G26P[19], the only G26 strain whose complete genotype constellation is known. The genotype constellation of 07N1760 was G26-P[19]-I12-R1-C1-M1-A8-N1-T1-E1-H1, a unique constellation identical to that of the Vietnamese 30378 except the VP6 gene. Phylogenetic analysis revealed that both strains were unrelated at the lineage level despite their similar genotype constellation. The I12 VP6 gene of 07N1760 was highly divergent from the six currently deposited I12 sequences in the GenBank. Except for its NSP2 gene, the remaining genes of 07N1760 shared lineages with porcine and porcine-like human RVA genes. The NSP2 gene belonged to a human RVA N1 lineage which was distinct from typical porcine and porcine-like human lineages. In conclusion, the Nepali G26P[19] strain 07N1760 was a porcine RVA strain which derived an NSP2 gene from a human Wa-like RVA strain by intra-genotype reassortment probably after transmission to the human host.

Phylogenetic inference of the porcine Rotavirus A origin of the human G1 VP7 gene.

Rotavirus A (RVA) is an important cause of acute gastroenteritis in children worldwide. The most common VP7 genotype of human RVA is G1, but G1 is rarely detected in porcine strains. To understand the evolutionary relationships between human and porcine G1 VP7 genes, we sequenced the VP7 genes of three Japanese G1 porcine strains; the first two (PRV2, S80B) were isolated in 1980 and the third (Kyusyu-14) was isolated in 2001. Then, we performed phylogenetic and in-silico structural analyses. All three VP7 sequences clustered into lineage VI, and the mean nucleotide sequence identity between any pair of porcine G1 VP7 sequences belonging to lineage VI was 91.9%. In contrast, the mean nucleotide sequence identity between any pair of human G1 VP7 sequences belonging to lineages I-V was 95.5%. While the mean nucleotide sequence identity between any pair of porcine lineage VI strain and human lineage I-V strain was 85.4%, the VP7 genes of PRV2 and a rare porcine-like human G1P[6] strain (AU19) were 98% identical, strengthening the porcine RVA origin of AU19. The phylogenetic tree suggests that human G1 VP7 genes originated from porcine G1 VP7 genes. The time of their most recent common ancestor was estimated to be 1948, and human and porcine RVA strains evolved along independent pathways. In-silico structural analyses identified 7 amino acid residues within the known neutralisation epitopes that show differences in electric charges and shape between different porcine and human G1 strains. When compared with much divergent porcine G1 VP7 lineages, monophyletic, less divergent human G1 VP7 lineages support the hypothesis that all human G1 VP7 genes included in this study originated from a rare event of a porcine RVA transmitting to humans that was followed by successful adaptation to the human host. By contrast, AU19 represents interspecies transmission that terminated in dead-end infection.

Molecular epidemiology of noroviruses detected in Vietnamese children with acute gastroenteritis from 2012 to 2015

&NA; Noroviruses, an important cause of diarrhoea in humans, are genetically diverse. The recent norovirus seasons recorded the emergence of new recombinants of the capsid and polymerase genotypes, with a global dominance of GII.Pe_GII.4 Sydney 2012 and GII.P17_GII.17 in Asian countries. However, the number of papers reporting the distribution of both polymerase and capsid genotypes circulating among children is scarce, with none from Vietnam. This study described both the polymerase and capsid genotypes of noroviruses circulating in Vietnamese children using stool specimens obtained under the World Health Organization rotavirus surveillance programme from 2012 to 2015. Of 350 specimens tested, noroviruses were detected in 90 (28 %) of 319 inpatient specimens and in 9 (29 %) of 31 outpatient specimens. The polymerase and capsid genotype combinations of GII.Pe_GII.4 Sydney 2012 and GII.P21_GII.3 were co‐dominant (51 and 24 %, respectively), both of which were recombinants, contributing to a high proportion (87 %) of recombinants among circulating noroviruses. GII.4 variants evolved in the same fashion in Vietnam as in other countries, with amino acid substitutions in the putative variant‐specific epitopes of the protruding domain. Unlike neighbouring countries where the predominance of GII.P17_GII.17 was reported, only one GII.P17_GII.17 strain was detected from an outpatient in 2015 in Vietnam. In conclusion, a substantial burden due to norovirus gastroenteritis hospitalizations among Vietnamese children was associated with circulating co‐dominant GII.Pe_GII.4 Sydney 2012 and GII.P21_GII.3 strains. Continued surveillance is necessary to monitor infection caused by GII.4 variants and that of GII.P17_GII.17 noroviruses in paediatric patients in Vietnam.

Early career researchers want Open Science

Open Science is encouraged by the European Union and many other political and scientific institutions. However, scientific practice is proving slow to change. We propose, as early career researchers, that it is our task to change scientific research into open scientific research and commit to Open Science principles.

Whole genome analysis of Vietnamese G2P[4] rotavirus strains possessing the NSP2 gene sharing an ancestral sequence with Chinese sheep and goat rotavirus strains

Because imminent introduction into Vietnam of a vaccine against Rotavirus A is anticipated, baseline information on the whole genome of representative strains is needed to understand changes in circulating strains that may occur after vaccine introduction. In this study, the whole genomes of two G2P[4] strains detected in Nha Trang, Vietnam in 2008 were sequenced, this being the last period during which virtually no rotavirus vaccine was used in this country. The two strains were found to be >99.9% identical in sequence and had a typical DS‐1 like G2‐P[4]‐I2‐R2‐C2‐M2‐A2‐N2‐T2‐E2‐H2 genotype constellation. Analysis of the Vietnamese strains with >184 G2P[4] strains retrieved from GenBank/EMBL/DDBJ DNA databases placed the Vietnamese strains in one of the lineages commonly found among contemporary strains, with the exception of the NSP2 and NSP4 genes. The NSP2 genes were found to belong to a previously undescribed lineage that diverged from Chinese sheep and goat rotavirus strains, including a Chinese rotavirus vaccine strain LLR with 95% nucleotide identity; the time of their most recent common ancestor was 1975. The NSP4 genes were found to belong, together with Thai and USA strains, to an emergent lineage (VIII), adding further diversity to ever diversifying NSP4 lineages. Thus, there is a need to enhance surveillance of locally‐circulating strains from both children and animals at the whole genome level to address the effect of rotavirus vaccines on changing strain distribution.

Porcine-like G3P[6] and G4P[6] rotavirus A strains detected from children with diarrhoea in Vietnam

Animal rotavirus A (RVA) strains can infect children and cause diarrhoea. We determined the full genome sequences of one G3P[6] strain (NT0001) and five G4P[6] strains (NT0042, NT0077, NT0205, NT0599, and NT0621) detected from children with diarrhoea in Vietnam in 2007-2008. Strain NT0001 had a genotype constellation of: G3-P[6]-I5-R1-C1-M1-A8-N1-T1-E1-H1, strain NT0042: G4-P[6]-I1-R1-C1-M1-A8-N1-T1-E1-H1, strain NT0077: G4-P[6]-I5-R1-C1-M1-A8-N1-T7-E1-H1, and strains NT0205, NT0599, and NT0621: G4-P[6]-I1-R1-C1-M1-A1-N1-T1-E1-H1. Sequence divergence data and phylogenetic analysis showed that they were different porcine RVA strains that independently and directly crossed the host species barrier to infect children.