Molecular Epidemiology of Adenovirus Type 21 Respiratory Strains Isolated From US Military Trainees (1996-2014).
BACKGROUND
The circulation of human adenovirus type 21 (HAdV21) in the United States has been documented since the 1960s in association with outbreaks of febrile respiratory illness (FRI) in military boot camps and civilian cases of respiratory disease.


METHODS
To describe the molecular epidemiology of HAdV21 respiratory infections across the country, 150 clinical respiratory isolates obtained from continuous surveillance of military recruit FRI, and 23 respiratory isolates recovered from pediatric and adult civilian cases of acute respiratory infection were characterized to compile molecular typing data spanning 37 years (1978-2014).


RESULTS
Restriction enzyme analysis and genomic sequencing identified 2 clusters of closely related genomic variants readily distinguishable from the prototype and designated 21a-like and 21b-like. A-like variants predominated until 1999. A shift to b-like variants was noticeable by 2007 after a 7-year period (2000-2006) of cocirculation of the 2 genome types. US strains are phylogenetically more closely related to European and Asian strains isolated over the last 4 decades than to the Saudi Arabian prototype strain AV-1645 isolated in 1956.


CONCLUSIONS
Knowledge of circulating HAdV21 variants and their epidemic behavior will be of significant value to local and global FRI surveillance efforts.
Lovelace Respiratory Research Institute, Albuquerque, New Mexico.
Adriana E
AE
Kajon
Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland.
Jun
J
Hang
Operational Infectious Diseases Department, Naval Health Research Center, San Diego, California.
Anthony
A
Hawksworth
Operational Infectious Diseases Department, Naval Health Research Center, San Diego, California.
David
D
Metzgar
Institute of Virology, Hannover Medical School, Germany.
Elias
E
Hage
Operational Infectious Diseases Department, Naval Health Research Center, San Diego, California.
Christian J
CJ
Hansen
Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland.
Robert A
RA
Kuschner
Operational Infectious Diseases Department, Naval Health Research Center, San Diego, California.
Patrick
P
Blair
Armed Forces Health Surveillance Center, Silver Spring, Maryland.
Kevin L
KL
Russell
Viral Diseases Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland.
Richard G
RG
Jarman
D000257:Adenoviridae Infections / Q000453:epidemiology* / Q000821:virology*; D000260:Adenoviruses, Human / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification; D004279:DNA, Viral / Q000235:genetics; D004196:Disease Outbreaks; D014644:Genetic Variation; D006801:Humans; D008889:Military Personnel; D017720:Molecular Epidemiology; D016133:Polymerase Chain Reaction; D011159:Population Surveillance; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000821:virology*; D013997:Time Factors; D014481:United States / Q000453:epidemiology
D004279:DNA, Viral
DNA; adenovirus evolution; military; molecular epidemiology