Molecular Epidemiology of Adenovirus Type 7 in the United States, 1966–20001

Abstract

Genetic variation among 166 isolates of human adenovirus 7 (Ad7) obtained from 1966 to 2000 from the United States and Eastern Ontario, Canada, was determined by genome restriction analysis. Most (65%) isolates were identified as Ad7b. Two genome types previously undocumented in North America were also identified: Ad7d2 (28%), which first appeared in 1993 and was later identified throughout the Midwest and Northeast of the United States and in Canada; and Ad7h (2%), which was identified only in the U.S. Southwest in 1998 and 2000. Since 1996, Ad7d2 has been responsible for several civilian outbreaks of Ad7 disease and was the primary cause of a large outbreak of respiratory illness at a military recruit training center. The appearance of Ad7d2 and Ad7h in North America represents recent introduction of these viruses from previously geographically restricted areas and may herald a shift in predominant genome type circulating in the United States.

Severe Pediatric Adenovirus 7 Disease in Singapore Linked to Recent Outbreaks across Asia

“…Ad7 has been reported to cause outbreaks in 3 main patterns: 1) severe disease among young children, especially during winter in temperate countries; 2) less severe disease in nonseasonal community outbreaks; and 3) outbreaks among military personnel (11). The outbreak we report was marked by severe disease among young children and mild disease among military personnel.…”

Impact of Human Adenovirus Serotype 7 in Hospitalized Children with Severe Fatal Pneumonia in the Philippines

“…A nationwide outbreak in 1995 in Japan was caused by HAdV type d2, which could have been imported from another Asian country. In South America, a switch from HAdV7c to 7h occurred in 1986, and HAdV7h has remained the dominant genome type, which has reportedly caused severe respiratory infections in Chile and Argentina (5,11,12,22). Although a higher virulence of HAdV7h was indicated during these outbreaks, there is no virological evidence to indicate increased virulence of HAdV7h.…”

“…Therefore, it is of great importance to decipher the clinical and molecular characteristics of HAdV. Although many studies have been published (2,5,18), data on the molecular epidemiology of HAdV in tropi- Table 1 : Synonymous mutation was observed.…”

“…Furthermore, a variety of genome types can be identified by the restriction fragment length polymorphism (RFLP) technique (6). Temporal and geographical distributions of serotypes and genome types have been reported (2,5,(7)(8)(9)(10)(11)(12). It has also been indicated that the emergence or switching of serotypes and genome types can cause HAdV outbreaks (8).…”

“…HAdV also plays an important role in pediatric infections and accounts for 2z-5z of respiratory illnesses and 4z-10z of pneumonia cases (4). HAdV serotype 7 (HAdV7) is most significantly associated with severe pneumonia and causes fatal infections even in healthy children in developed countries (5). Furthermore, a variety of genome types can be identified by the restriction fragment length polymorphism (RFLP) technique (6).…”