Functional analysis of the heterologous NSP1 genes in the genetic background of simian rotavirus SA11 - Brief report

Function of rotavirus NSP1 was analyzed by using single-NSP1 gene-substitut ion reassortants, SKF, SDF, and SNF which have the NSP1 gene derived from h uman rotaviruses KU, DS-1, and canine rotavirus K9, respectively, in the ge netic background of simian rotavirus SA11. The NSP1 genes from KU, DS-1, K9 , and SA11 exhibited 58-76% nucleotide sequence identity to one another. No substantial difference in viral growth was observed among the reassortants and SA11. However, production of NSP 1 was not detected in SNF when viral proteins were labelled with S-35-methionine during replication in MA104 cel ls, in contrast to SA11, SKF and SDF which exhibited evident expression of NSP1. Difference in reassortant formation was examined among the reassortan t clones generated between human rotavirus strain 69M and either of SA11, S KF or SNE Although reassortant formation rate was significantly lower in th e cross 69M x SNF than the other crosses, selection rates of RNA segments f rom parent strain 69M in the resultant reassortants was similar among the c rosses. Selectivity of homologous and heterologous NSP1 genes in SA11 backg round was also analyzed by mixed infection and multiple passages among the single-NSP1 gene-reassortants and/or SA11. KU NSP1 gene was selected most f requently, whereas homologous (SA11) NSP1 gene was least efficiently segreg ated. These results indicated that viral growth and genome segment reassort ment with other viruses may not be influenced by the presence of heterologo us NSP1 and its expression level, while genomic diversity of NSP1 genes mig ht have been associated with the relative adaptability to the genetic backg round of SA11.