QUANTITATIVE-ANALYSIS OF GENOMIC POLYMORPHISM OF HERPES-SIMPLEX VIRUSTYPE-1 STRAINS FROM 6 COUNTRIES - STUDIES OF MOLECULAR EVOLUTION AND MOLECULAR EPIDEMIOLOGY OF THE VIRUS
H. Sakaoka et al., QUANTITATIVE-ANALYSIS OF GENOMIC POLYMORPHISM OF HERPES-SIMPLEX VIRUSTYPE-1 STRAINS FROM 6 COUNTRIES - STUDIES OF MOLECULAR EVOLUTION AND MOLECULAR EPIDEMIOLOGY OF THE VIRUS, Journal of General Virology, 75, 1994, pp. 513-527
Using the presence or absence of 63 variable restriction endonuclease
(RE) sites selected from 225 sites with six REs, genomic polymorphism
of 242 herpes simplex virus type 1 (HSV-1) strains from six countries
(Japan, Korea, China, Sweden, U.S.A. and Kenya) was quantitatively ana
lysed. Twenty-five of the 63 sites were found to differ between Korean
and Kenyan strains. In contrast, only three and six sites were found
to differ between isolates from Sweden and the U.S.A. and between thos
e from Korea and China, respectively, suggesting that they are closely
related to each other. In this way, characterization of 63 sites enab
led us to categorize 186 distinct HSV-1 genotypes from 242 individuals
. Some strains from Japan, Korea and China shared the same genotypes,
indicating that they are phylogenetically closely related. Many signif
icant correlation coefficients ( \ r \ > 0.42; P < 0.01) between pairs
of sites were found in isolates from the three Asian countries (Japan
, Korea and China) as well as in those from Sweden and the U.S.A., sug
gesting that HSV-1 strains from within the same ethnic groups are evol
utionarily closer. The average number of nucleotide substitutions per
nucleotide, as defined by nucleotide diversity (pi), was estimated for
HSV-1 genomes within (pi(X) or pi(Y)) and between (pi(XY)) countries.
On the basis of 225 sites, nucleotide diversity for Kenyan isolates w
as 0.0056, almost three times higher than that for Korean isolates, im
plying that Kenyan HSV-1 genomes are much more diverse than those from
Korea. In addition, the diversity between HSV-1 isolates from differe
nt countries (pi(XY)) was highest between isolates from the three Asia
n countries and Kenya (0.0075 to 0.0081) and lowest among those from t
he three Asian countries (0.0032 to 0.0040). The mutation rate (lambda
) for HSV-1 was estimated to be 3.5 x 10(-8)/site/year. Ah these findi
ngs show that the evolution of HSV-1 may be host-dependent and very sl
ow.