NSP1

About: NSP1 is a research topic. Over the lifetime, 248 publications have been published within this topic receiving 12044 citations.

Genomic Diversity Through Gene Reassortment and Antigenic Drift and Molecular Epidemiology of Rotaviruses in India

Abstract: A review. Long term epidemiol. studies on both symptomatic and asymptomatic rotavirus infections during the period 1988 to 1999 in Bangalore revealed a consistently high rate (.apprx.60%) of asymptomatic infection of neonates born in hospitals/clinics by unusual P[11]G10 type strains. The prototype neonatal strain I321 was shown to be a reassortant between a P[11]G10 bovine rotavirus and a human rotavirus with all the genes, except for two genes encoding the nonstructural proteins NSP1 and NSP3, derived from the bovine parent. Neonatal infections were totally dominated by I321-like strains. Neonatal infections appear to confer protection against subsequent rotavirus illness as evident from the two-year follow-up study of I321-infected newborn children as well as by the significant reduction in rotavirus illness in Bangalore for the last 8 years. Another reassortant neonatal strain 116E (P[11]G9) was also isolated in New Delhi. G3 type strains were more prevalent in symptomatic infections in Bangalore throughout the study period. The order of prevalence was G3 (36.6) > G2 (22.0%) > G1 (17.1%) > G4 (6.0%). There was no change in the epidemiology situation during this period. In contrast, serotype G1 was found to be more prevalent in other regions of the country. Majority of the G2-like strains were nontypeable in serotyping ELISA due to broad cross-reactivity to serotyping mAbs. This appears to be due to amino acid substitutions in the antigenic regions of VP7 as well as in VP4 and these strains probably represent a G2 subtype. An unusual G2 strain assocd. with diarrhoea, having 'long' e-type and SG1 specificity has been isolated in Manipur and appears to have been evolved by gene reassortment between a P[4]G2 human strain and a porcine strain. Direct transmission of bovine G8 strains from cattle was observed to cause severe diarrhoea in children in Mysore. Serotype G10 was found to dominate infections in cattle in India and represented 55.0% - 85.0% of the isolates in different farms across the country. Serotype G6 was negligible in Indian cattle and G8 strains were detected in all the regions (5.8%). Another surprising observation was the presence of G3 strains in significant nos. (10.7%) in all the regions. The prototype bovine G3 strain G3 was shown to be a reassortant between a bovine G8 strain and an animal G3 strain (simian, canine or equine). A novel rotavirus was isolated from a single farm in Bangalore and was shown to represent the new serotype P[21]G15. The findings from our lab. are of great significance since they provided strong epidemiol. basis for the origin of P[11]G10 and P[11]G9 reassortant asymptomatic neonatal strains in different regions of the country. Age-old Indian traditions, close proximity of majority of the Indian population with cattle, and environmental conditions appear to facilitate inter-species transmission of rotaviruses between humans and cattle and cattle and animals and evolution of novel strains in India.

Functional analysis of the heterologous NSP1 genes in the genetic background of simian rotavirus SA11.

Abstract: Function of rotavirus NSP1 was analyzed by using single-NSP1 gene-substitution reassortants, SKF, SDF, and SNF which have the NSP1 gene derived from human rotaviruses KU, DS-1, and canine rotavirus K9, respectively, in the genetic background of simian rotavirus SAff11. The NSP1 genes from KU, DS-1, K9, and SAff11 exhibited 58–76% nucleotide sequence identity to one another. No substantial difference in viral growth was observed among the reassortants and SAff11. However, production of NSP1 was not detected in SNF when viral proteins were labelled with 35S-methionine during replication in MAff104 cells, in contrast to SAff11, SKF and SDF which exhibited evident expression of NSP1. Difference in reassortant formation was examined among the reassortant clones generated between human rotavirus strain 69M and either of SAff11, SKF or SNF. Although reassortant formation rate was significantly lower in the cross 69M × SNF than the other crosses, selection rates of RNA segments from parent strain 69M in the resultant reassortants was similar among the crosses. Selectivity of homolog- ous and heterologous NSP1 genes in SAff11 background was also analyzed by mixed infection and multiple passages among the single-NSP1 gene-reassortants and/or SAff11. KU NSP1 gene was selected most frequently, whereas homologous (SAff11) NSP1 gene was least efficiently segregated. These results indicated that viral growth and genome segment reassortment with other viruses may not be influenced by the presence of heterologous NSP1 and its expression level, while genomic diversity of NSP1 genes might have been associated with the relative adaptability to the genetic background of SAff11.

The shift from low to high non-structural protein 1 expression in rotavirus-infected MA-104 cells

Abstract: A hallmark of group/species A rotavirus (RVA) replication in MA-104 cells is the logarithmic increase in viral mRNAs that occurs four-12 h post-infection. Viral protein synthesis typically lags closely behind mRNA synthesis but continues after mRNA levels plateau. However, RVA non-structural protein 1 (NSP1) is present at very low levels throughout viral replication despite showing robust protein synthesis. NSP1 has the contrasting properties of being susceptible to proteasomal degradation, but being stabilised against proteasomal degradation by viral proteins and/or viral mRNAs. We aimed to determine the kinetics of the accumulation and intracellular distribution of NSP1 in MA-104 cells infected with rhesus rotavirus (RRV). NSP1 preferentially localises to the perinuclear region of the cytoplasm of infected cells, forming abundant granules that are heterogeneous in size. Late in infection, large NSP1 granules predominate, coincident with a shift from low to high NSP1 expression levels. Our results indicate that rotavirus NSP1 is a late viral protein in MA-104 cells infected with RRV, presumably as a result of altered protein turnover.

Purification, crystallization and preliminary X-ray analysis of nonstructural protein 2 (nsp2) from avian infectious bronchitis virus

Abstract: Avian infectious bronchitis virus (IBV) is a member of the group III coronaviruses, which differ from the other groups of coronaviruses in that they do not encode the essential pathogenic factor nonstructural protein 1 (nsp1) and instead start with nsp2. IBV nsp2 is one of the first replicase proteins to be translated and processed in the viral life cycle; however, it has an entirely unknown function. In order to better understand the structural details and functional mechanism of IBV nsp2, the recombinant protein was cloned, overexpressed in Escherichia coli, purified and crystallized. The crystals diffracted to 2.8 A resolution and belonged to space group P21, with unit-cell parameters a = 57.0, b = 192.3, c = 105.7 A, β = 90.8°. Two molecules were found in the asymmetric unit; the Matthews coefficient was 3.9 A3 Da−1, corresponding to a solvent content of 68.2%.