中文摘要：

<正>Dear Editor,The packaging of viral genomic RNA into virus par-ticles is a critical step for virus maturation.This stepincludes the recognition and interaction between the nu-cleocapsid protein and viral RNA.The necessity of viralRNA packaging signals has been described for manyRNA viruses(Cologna R,et al.,2000;Narayanan K,et al.,2001;Tchatalbachev S,et al.,2001).Occasionalpackaging of nongenomic viral RNAs and cellular RNAs

英文摘要：

Dear Editor,The packaging of viral genomic RNA into virus particles is a critical step for virus maturation.This step includes the recognition and interaction between the nucleocapsid protein and viral RNA.The necessity of viral RNA packaging signals has been described for many RNA viruses （Cologna R,et al.,2000;Narayanan K,et al.,2001;Tchatalbachev S,et al.,2001）.Occasional packaging of nongenomic viral RNAs and cellular RNAs results in noninfectious virions,and casual packaging of cellular RNA into viral particles would overwhelm the ability of viral genomic RNA to contact limited assembly factors.Therefore,viruses have probably developed a defensive strategy for the specific packaging of genomic RNA into virus particles.The packaging signals of some RNA viruses are located within more than one viral genomic region （Luytjes W,et al.,1989;Pattnaik A K,et al.,1995;Wei N,et al.,1990）.For many viruses,it is unknown whether a single region or a combination of multiple genomic regions is necessary for viral RNA packaging.