Poliomyelitis. Genome structure and function, infection cycle and molecular epidemiology

ABSTRACT

Polioviruses, like other enteroviruses, area member of the family picornaviridae. They are among the smallest ribonucleic acid [RNA] viruses measuring 30nm in diameter and the shape of the virus is as show in figure 1. Polioviruses are the principal cause of acute flaccid paralysis [AFP], usually referred to as polio. Poliovirus is a single stranded, positive sense RNA virus. The virion RNA, which acts as the viral messenger, has a single large open reading frame [ORF] of approximately 7.4 kb for translation into one very large polyprotein containing 2207 amino acids [AA] with a molecular weight approaching 240.00. initial translation of the genome into a polyprotein precursor, coupled with translational proteolytic processing, results in the production of four viral about twenty other proteins derived from the polyprotein by a series of proteolytic cleavages. The gene order of poliovirus has been established as 5' V Pg- ntr VPO - VP3 - VP1 - 2A - 2B - 2C - 3A - 3B - 3C - 3D - NTR - AAA - 3'as shown in figure 2