Molecular characterization of the VP1, VP2, VP4, VP6, NSP1 and NSP2 genes of bovine group B rotaviruses: identification of a novel VP4 genotype

Poor Endometrial Proliferation After Clomiphene is Associated With Altered Estrogen Action

CONTEXT

Suboptimal endometrial thickening is associated with lower pregnancy rates and occurs in some infertile women treated with clomiphene.

OBJECTIVE

To examine cellular and molecular differences in the endometrium of women with suboptimal vs optimal endometrial thickening following clomiphene.

METHODS

Translational prospective cohort study from 2018 to 2020 at a university-affiliated clinic. Reproductive age women with unexplained infertility treated with 100 mg of clomiphene on cycle days 3 to 7 who developed optimal (≥8mm; n = 6, controls) or suboptimal (<6mm; n = 7, subjects) endometrial thickness underwent preovulatory blood and endometrial sampling. The main outcome measures were endometrial tissue architecture, abundance and location of specific proteins, RNA expression, and estrogen receptor (ER) α binding.

RESULTS

The endometrium of suboptimal subjects compared with optimal controls was characterized by a reduced volume of glandular epithelium (16% vs 24%, P = .01), decreased immunostaining of markers of proliferation (PCNA, ki67) and angiogenesis (PECAM-1), increased immunostaining of pan-leukocyte marker CD45 and ERβ, but decreased ERα immunostaining (all P < .05). RNA-seq identified 398 differentially expressed genes between groups. Pathway analysis of differentially expressed genes indicated reduced proliferation (Z-score = -2.2, P < .01), decreased angiogenesis (Z-score = -2.87, P < .001), increased inflammation (Z-score = +2.2, P < .01), and ERβ activation (Z-score = +1.6, P < .001) in suboptimal subjects. ChIP-seq identified 6 genes bound by ERα that were differentially expressed between groups (P < .01), some of which may play a role in implantation.

CONCLUSION

Women with suboptimal endometrial thickness after clomiphene exhibit aberrant ER expression patterns, architectural changes, and altered gene and protein expression suggesting reduced proliferation and angiogenesis in the setting of increased inflammation.

Diversity in VP3, NSP3, and NSP4 of rotavirus B detected from Japanese cattle

Bovine rotavirus B (RVB) is an etiological agent of diarrhea mostly in adult cattle. Currently, a few sequences of viral protein (VP)1, 2, 4, 6, and 7 and nonstructural protein (NSP)1, 2, and 5 of bovine RVB are available in the DDBJ/EMBL/GenBank databases, and none have been reported for VP3, NSP3, and NSP4. In order to fill this gap in the genetic characterization of bovine RVB strains, we used a metagenomics approach and sequenced and analyzed the complete coding sequences (CDS) of VP3, NSP3, and NSP4 genes, as well as the partial or complete CDS of other genes of RVBs detected from Japanese cattle. VP3, NSP3, and NSP4 of bovine RVBs shared low nucleotide sequence identities (63.3-64.9% for VP3, 65.9-68.2% for NSP3, and 52.6-56.2% for NSP4) with those of murine, human, and porcine RVBs, suggesting that bovine RVBs belong to a novel genotype. Furthermore, significantly low amino acid sequence identities were observed for NSP4 (36.1-39.3%) between bovine RVBs and the RVBs of other species. In contrast, hydrophobic plot analysis of NSP4 revealed profiles similar to those of RVBs of other species and rotavirus A (RVA) strains. Phylogenetic analyses of all gene segments revealed that bovine RVB strains formed a cluster that branched distantly from other RVBs. These results suggest that bovine RVBs have evolved independently from other RVBs but in a similar manner to other rotaviruses. These findings provide insights into the evolution and diversity of RVB strains.

Silencing the alarms: Innate immune antagonism by rotavirus NSP1 and VP3

The innate immune response involves a broad array of pathogen sensors that stimulate the production of interferons (IFNs) to induce an antiviral state. Rotavirus, a significant cause of childhood gastroenteritis and a member of the Reoviridae family of segmented, double-stranded RNA viruses, encodes at least two direct antagonists of host innate immunity: NSP1 and VP3. NSP1, a putative E3 ubiquitin ligase, mediates the degradation of cellular factors involved in both IFN induction and downstream signaling. VP3, the viral capping enzyme, utilizes a 2H-phosphodiesterase domain to prevent activation of the cellular oligoadenylate synthase (OAS)/RNase L pathway. Computational, molecular, and biochemical studies have provided key insights into the structural and mechanistic basis of innate immune antagonism by NSP1 and VP3 of group A rotaviruses (RVA). Future studies with non-RVA isolates will be essential to understand how other rotavirus species evade host innate immune responses.

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Rotavirus NSP1 and VP3 directly antagonize host innate immune pathways.

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NSP1, a putative E3 ubiquitin ligase, mediates turnover of multiple immune factors.

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VP3, the viral capping enzyme, has phosphodiesterase activity to block OAS/RNase L.

Rotavirus RNA polymerases resolve into two phylogenetically distinct classes that differ in their mechanism of template recognition

Rotaviruses (RVs) are segmented double-stranded RNA viruses that cause gastroenteritis in mammals and birds. Within the RV genus, eight species (RVA-RVH) have been proposed. Here, we report the first RVF and RVG sequences for the viral RNA polymerase (VP1)-encoding segments and compare them to those of other RV species. Phylogenetic analyses indicate that the VP1 RNA segments and proteins resolve into two major clades, with RVA, RVC, RVD and RVF in clade A, and RVB, RVG and RVH in clade B. Plus-strand RNA of clade A viruses, and not clade B viruses, contain a 3'-proximal UGUG cassette that serves as the VP1 recognition signal. VP1 structures for a representative of each RV species were predicted using homology modeling. Structural elements involved in interactions with the UGUG cassette were conserved among VP1 of clade A, suggesting a conserved mechanism of viral RNA recognition for these viruses.

Genetic divergence and classification of non-structural protein 1 among porcine rotaviruses of species B

Porcine rotavirus B (RVB) has frequently been detected in diarrhoea of suckling and weaned pigs. Moreover, epidemiological studies using ELISA have demonstrated high antibody prevalence in sera from sows, indicating that RVB infections are widespread. Because it is difficult to propagate RVBs serially in cell culture, genetic analysis of RNA segments of porcine RVBs other than those encoding VP7 and NSP2 has been scarcely performed. We conducted sequence and phylogenetic analyses focusing on non-structural protein 1 (NSP1), using 15 porcine RVB strains isolated from diarrhoeic faeces collected around Japan. Sequence analysis showed that the porcine NSP1 gene contains two overlapping ORFs. Especially, peptide 2 of NSP1 retains highly conserved cysteine and histidine residues among RVBs. Comparison of NSP1 nucleotide and deduced amino acid sequences from porcine RVB strains demonstrated low identities to those from other RVB strains. Phylogenetic analysis of RVB NSP1 revealed the presence of murine, human, ovine, bovine and porcine clusters. Furthermore, the NSP1 genes of porcine RVBs were divided into three genotypes, suggesting the possibility that porcine species might be an original host of RVB infection. Of nine strains common to those used in our previous study, only one strain was classified into a different genotype from the others in the analysis of VP7, in contrast to the analysis of NSP1, where all belonged to the same cluster. This fact suggests the occurrence of gene reassortment among porcine RVBs. These findings should provide more beneficent information to understand the evolution and functions of RVBs.

Genomic evolution, host-species barrier, reassortment and classification of rotaviruses

Evaluation of: Yamamoto D, Ghosh S, Ganesh B et al.: Analysis on genetic diversity and molecular evolution of human group B rotaviruses based on whole genome segments. J. Gen. Virol. 91(Pt 7), 1772–1781 (2010). Rotaviruses are members of the Reoviridae family, causing severe diarrheal illness and death in humans and animals. They have been subdivided into at least seven serological groups (A–G), and, recently, a new rotavirus known as ‘new adult diarrhea virus’ or ADRV-N was discovered. Only in group A rotaviruses have a substantial number of strains been analyzed completely on the molecular level. For groups B, C and ADRV-N rotaviruses a very limited number of complete genomes are available, and for group D, E and F no sequence data are available at all. Here, Yamamoto and colleagues describe the full genomic characterization of four human group B rotaviruses isolated in India, Bangladesh and Myanmar. These four strains were analyzed phylogenetically and individual gene segments were compared with their group A and C counterparts, indicating that functionally important motifs and structural characteristics were conserved. This study, together with others, highlights the need for complete genome analysis of rotaviruses, in order to study their genetic evolution, the occurrence of reassortments, crossing of the host-species barrier and their classification. Upcoming new mass sequencing technologies are expected to speed up the process of filling in the gaps in our data.

Analysis of genetic diversity and molecular evolution of human group B rotaviruses based on whole genome segments

Group B rotavirus (GBR) is a rare enteric pathogen that causes severe diarrhoea, primarily in adults. Nearly full-length sequences of all 11 RNA segments were determined for human GBRs detected recently in India (IDH-084 in 2007, IC-008 in 2008), Bangladesh (Bang117 in 2003) and Myanmar (MMR-B1 in 2007), and analysed phylogenetically with the sequence data of GBRs reported previously. All RNA segments of GBR strains from India, Bangladesh and Myanmar showed >95 % nucleotide sequence identities. Among the 11 RNA segments, the VP6 and NSP2 genes showed the highest identities (>98 %), whilst the lowest identities were observed in the NSP4 gene (96.1 %), NSP5 gene (95.6 %) and VP8*-encoding region of the VP4 gene (95.9 %). Divergent or conserved regions in the deduced amino acid sequences of GBR VP1-VP4 and NSP1-NSP5 were similar to those in group A rotaviruses (GARs), and the functionally important motifs and structural characteristics in viral proteins known for GAR were conserved in all of the human GBRs. These findings suggest that, whilst the degree of genetic evolution may be dependent on each RNA segment, human GBR may have been evolving in a similar manner to GAR, associated with the similar functional roles of individual viral proteins.