Rotaviruses (RVs) are major causes of life-threatening diarrheal disease in infants and young children worldwide. Particles are non-enveloped with a complex structure composed of three concentric protein shells that surround the genome of 11 segments of double-stranded (ds) RNA. Similar to influenza viruses, RVs exhibit enormous genetic and strain diversity as a result of point mutations and genetic reassortment between co-circulating strains, and zoonotic infection. How this expanding RV diversity will affect the efficacy of currently available vaccines over time is unclear. In additio to being clinically important, RVs serve as outstanding models to dissect cytoplasmic replication and encapsidation of 11 segments of dsRNA, a puzzle that has fascinated virologists since the first description of these viruses. Our long-term goal is to gain a comprehensive and mechanistic understanding of the elaborate processes that underlie RV replication. Exciting discoveries from our recent work have resulted in several paradigm shifts including i) the VP8* domain of the VP4 spike that mediates cell attachment binds non-sialylated glycans such as histoblood group antigens, (ii) conformational transitions in the VP4 spike mediate virus entry into cells, (iii) serotype-dependent variation occurs in the spike structure, (iv) hitherto unsuspected new enzymatic and RNA binding activities, and conformational switches are present in a nonstructural protein (NSP2) central to RNA replication. In addition, a RV protein (NSP1) with unique properties as an interferon antagonist that is important in host range restriction has been successfully crystallized. This progress forms the foundation for new studies proposed in this competitive renewal application that continue to seek fundamental mechanistic insight into RV biology using a multipronged approach that includes crystallographic and cryo-EM techniques, high- throughput glycan array screening, as well as novel infectivity, enzymatic and functional assays.
The specific aims of our proposed work are: (1) to test the hypotheses that genotypic diversity in VP8* of human RVs (hRVs) allows for significant variations in glycan specificity, which may have implications in cell tropism, host specificity, host adaptation and interspecies transmission;and that serotype variations between animal and hRV impact spike structure by determining a subnanometer cryo-EM structure of a globally dominant hRV strain;(2) to examine the hypothesis that the RNA binding multi-functional NSP2 octamer, with built-in structural cues and enzymatic activities, is the master regulator that coordinates viroplasm formation, genome replication/packaging and particle assembly to gain a fundamental understanding of the mechanisms that govern these intricate processes, and (3) to determine the molecular basis for strain-dependent and species-dependent IFN antagonism by RVs, by determining the X-ray structures of two NSP1s representing two different host systems (simian and human). Our structural studies may provide insight into manipulation of the NSP1 gene to design a rationally attenuated, second-generation RV vaccine.
Rotavirus is the major pathogen of life-threatening diarrhea in children under 5 years old, and it accounts for more than half a million deaths annually. With an innate ability of RVs to mutate and diversify, it is unclear if the current vaccines will remain efficacious over time. Our proposed studies are designed to provide a structure-based understanding of how different strains of rotavirus, especially human rotaviruses with recognized unique properties, interact with the host, counter the innate antiviral response, and replicate. We expect that the gained knowledge will explain how the multiple genome segments become encapsidated and will help develop new antiviral strategies.
| Hu, Liya; Sankaran, Banumathi; Laucirica, Daniel R et al. (2018) Glycan recognition in globally dominant human rotaviruses. Nat Commun 9:2631 |
| Ramani, Sasirekha; Stewart, Christopher J; Laucirica, Daniel R et al. (2018) Human milk oligosaccharides, milk microbiome and infant gut microbiome modulate neonatal rotavirus infection. Nat Commun 9:5010 |
| Criglar, Jeanette M; Anish, Ramakrishnan; Hu, Liya et al. (2018) Phosphorylation cascade regulates the formation and maturation of rotaviral replication factories. Proc Natl Acad Sci U S A 115:E12015-E12023 |
| Shanker, Sreejesh; Hu, Liya; Ramani, Sasirekha et al. (2017) Structural features of glycan recognition among viral pathogens. Curr Opin Struct Biol 44:211-218 |
| Ramani, Sasirekha; Hu, Liya; Venkataram Prasad, B V et al. (2016) Diversity in Rotavirus-Host Glycan Interactions: A ""Sweet"" Spectrum. Cell Mol Gastroenterol Hepatol 2:263-273 |
| Ogden, Kristen M; Prasad, B V Venkataram (2015) Quelling an innate response to dsRNA. Oncotarget 6:28535-6 |
| Hu, Liya; Ramani, Sasirekha; Czako, Rita et al. (2015) Structural basis of glycan specificity in neonate-specific bovine-human reassortant rotavirus. Nat Commun 6:8346 |
| Ogden, Kristen M; Hu, Liya; Jha, Babal K et al. (2015) Structural basis for 2'-5'-oligoadenylate binding and enzyme activity of a viral RNase L antagonist. J Virol 89:6633-45 |
| Criglar, Jeanette M; Hu, Liya; Crawford, Sue E et al. (2014) A novel form of rotavirus NSP2 and phosphorylation-dependent NSP2-NSP5 interactions are associated with viroplasm assembly. J Virol 88:786-98 |
| Venkataram Prasad, B V; Shanker, Sreejesh; Hu, Liya et al. (2014) Structural basis of glycan interaction in gastroenteric viral pathogens. Curr Opin Virol 7:119-27 |
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