Molecular evolution of enterovirus 68 detected in the Philippines.
BACKGROUND
Detection of Enterovirus 68 (EV68) has recently been increased. However, underlying evolutionary mechanism of this increasing trend is not fully understood.


METHODS
Nasopharyngeal swabs were collected from 5,240 patients with acute respiratory infections in the Philippines from June 2009 to December 2011. EV68 was detected by polymerase chain reaction (PCR) targeting for 5' untranslated region (5'UTR), viral protein 1 (VP1), and VP4/VP2. Phylogenetic trees were generated using the obtained sequences.


RESULTS
Of the 5,240 tested samples, 12 EV68 positive cases were detected between August and December in 2011 (detection rate, 0.23%). The detection rate was higher among inpatients than outpatients (p<0.0001). Among VP1 sequences detected from 7 patients in 2011, 5 in lineage 2 were diverged from those detected in the Philippines in 2008, however, 2 in lineage 3 were not diverged from strains detected in the Philippines in 2008 but closely associated with strains detected in the United States. Combined with our previous report, EV68 occurrences were observed twice in the Philippines within the last four years.


CONCLUSIONS
EV68 detections might be occurring in cyclic patterns, and viruses might have been maintained in the community while some strains might have been newly introduced.
Tohoku University Graduate School of Medicine, Sendai, Japan.
Tadatsugu
T
Imamura
Akira
A
Suzuki
Socorro
S
Lupisan
Michiko
M
Okamoto
Rapunzel
R
Aniceto
Rutchie J
RJ
Egos
Edgardo E
EE
Daya
Raita
R
Tamaki
Mariko
M
Saito
Naoko
N
Fuji
Chandra Nath
CN
Roy
Jaime M
JM
Opinion
Arlene V
AV
Santo
Noel G
NG
Macalalad
Amado
A
Tandoc
Lydia
L
Sombrero
Remigio
R
Olveda
Hitoshi
H
Oshitani
D020121:5' Untranslated Regions; D000293:Adolescent; D000328:Adult; D000368:Aged; D001499:Bayes Theorem; D036022:Capsid Proteins / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000235:genetics* / Q000302:isolation & purification; D004770:Enterovirus / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D004769:Enterovirus Infections / Q000175:diagnosis* / Q000235:genetics / Q000821:virology; D019143:Evolution, Molecular; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010679:Philippines; D010802:Phylogeny; D011446:Prospective Studies; D055815:Young Adult
D020121:5' Untranslated Regions; D036022:Capsid Proteins; D004279:DNA, Viral