Akashi H; Kaku Y; Kong XG; Pang H.
Sequence determination
and phylogenetic analysis of the Akabane bunyavirus
S RNA genome
segment.
Journal of General Virology,
1997 Nov, 78 ( Pt 11):2847-51.
Abstract: The nucleotide sequence of
the small (S) RNA segment of Akabane (AKA)
bunyavirus was determined.
The segment is 858 nucleotides long and contains
two overlapping
open reading frames (ORFs), which encode the nucleocapsid
(N) and nonstructural
(NSs) proteins, consistent with other bunyaviruses.
Comparisons with
the Aino virus S RNA sequence indicated that there is
73.5% identity in
nucleotide sequence. However, the sequence identity of
the 5' non-coding
region of the genomic RNA between these two viruses is
only 55%. The N
ORFs from 20 Japanese and 2 Australian isolates of AKA
virus were sequenced
and subjected to phylogenetic analysis. This suggested
that AKA virus has
evolved in multiple lineages. Twenty-three isolates were
grouped into three
major clusters, and the cluster which includes recent
isolates was subdivided
into two branches. Thus, phylogenetic analysis of
the AKA virus N
protein gene gives a greater insight into bunyavirus
evolution.
La Crosse Virus
Huang C; Thompson WH; Karabatsos N;
Grady L; Campbell WP.
Evidence that fatal
human infections with La Crosse virus may be
associated with
a narrow range of genotypes.
Virus Research, 1997 May, 48(2):143-8.
Abstract: La Crosse (LAC) virus belongs to
the California (CAL) serogroup of
the genus Bunyavirus,
family Bunyaviridae. It is considered one of the most
important mosquito-borne
pathogens in North America, especially in the
upper Mid-West, where
it is associated with encephalitis during the time of
year when mosquitoes are
active. Infections occur most frequently in
children and young adults
and, while most cases are resolved after a period
of intense illness, a
small fraction (< 1%) are fatal. At present there
have only been three isolates
of LAC virus from humans all made from brain
tissue postmortem. The
cases yielding viruses are separated chronologically
by 33 years and geographically
from Minnesota/Wisconsin (1960, 1978)
to Missouri (1993). The
M RNA sequence of the first two isolates was
previously reported. The
present study extends the observations to the
isolate from the 1993
case and includes several mosquito isolates as well.
A comparison of the M
RNAs of these viruses shows that for the human
isolates both nucleotide
sequence and the deduced amino-acid sequence of
the encoded proteins are
highly conserved, showing a maximum variation of
only 0.91% and 0.69%,
respectively. This high degree of conservation over
time and space leads to
the hypothesis that human infections with this
particular genotype of
LAC virus are those most likely to have a fatal
outcome. It is also shown
that a virus with this genotype could be found
circulating in mosquitoes
in an area more or less intermediate between the
locations of the first
and second fatal cases.