In 1996, three adenovirus type 7 (Ad7) strains were isolated from children with fever and
upper respiratory diseases in Japan. Restriction endonucleases (REs) analysis and PCR
amplification of the E3 7·7 kDa ORF revealed that these strains were genotype Ad7h and
closely related to an Argentine Ad7h strain, which has been reported to be highly virulent and
so far predominant only in South America. These strains showed weak cross-neutralizing
activity and specific haemagglutination-inhibition activity to Ad3 antiserum. The present
findings suggest that Ad7h in South America has spread to other parts of the world. Since the
seroprevalence to Ad7 in the current Japanese population is very low due to the absence of
Ad7 circulation in Japan for decades, Ad7 outbreak as a typical case of re-emerging infectious
diseases is a cause for serious concern.