Molecular identification and characterization of two proposed new enterovirus serotypes, EV74 and EV75

1 Respiratory and Enteric Viruses Branch, Division of Viral and Rickettsial Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Mailstop G-17, Atlanta, GA 30333, USA 2 Viral and Rickettsial Disease Laboratory, California Department of Health Services, Richmond, CA, USA 3 Instituto Nacional de Enfermedades Infectiosos – ANLIS ‘Carlos Malbran’, Buenos Aires, Argentina 4 Department of Virology, Swedish Institute for Disease Control, Solna, Sweden 5 Institute of Public Health, Dhaka, Bangladesh 6 Centre National de Référence des Entérovirus, Lyon, France 7 Department of Health, Queen Mary Hospital, Hong Kong Special Administrative Region, People's Republic of China 8 National Polio Laboratory, Baghdad, Iraq 9 Department of Laboratories, Directorate General of Health Affairs, Ministry of Health, Muscat, Oman Correspondence M. Steven Oberste soberste{at}cdc.gov Sequencing of the gene that encodes the capsid protein VP1 has been used as a surrogate for antigenic typing in order to distinguish enterovirus serotypes; three new serotypes were identified recently by this method. In this study, 14 enterovirus isolates from six countries were characterized as members of two new types within the species Human enterovirus B , based on sequencing of the complete capsid-encoding (P1) region. Isolates within each of these two types differed significantly from one another and from all other known enterovirus serotypes on the basis of sequences that encode either VP1 alone or the entire P1 region. Members of each type were 77·2 % identical to one another (89·5 % amino acid identity) in VP1, but members of the two different types differed from one another and from other enteroviruses by 31 % in nucleotide sequence (25 % amino acid sequence difference), indicating that the two groups represent separate new candidate enterovirus types. The complete P1 sequences differed from those of all other enterovirus serotypes by 31 % (26 % amino acid sequence difference), but were highly conserved within a serotype (