Abstract:
Crimean–Congo haemorrhagic fever virus
(CCHFV) is a member of the Bunyaviridae
family with a tripartite, negative sense RNA
genome. This study used predictive software
to analyse the L (large), M (medium), and S
(small) segments of 14 southern African
CCHFV isolates. The OTU-like cysteine protease
domain and the RdRp domain of the L
segment are highly conserved among southern
African CCHFV isolates. The M segment
encodes the structural glycoproteins, GN and
GC, and the non-structural glycoproteins
which are post-translationally cleaved at
highly conserved furin and subtilase SKI-1
cleavage sites. All of the sites previously
identified were shown to be conserved
among southern African CCHFV isolates. The
heavily O-glycosylated N-terminal variable
mucin-like domain of the M segment shows
the highest sequence variability of the CCHFV
proteins. Five transmembrane domains are
predicted in the M segment polyprotein resulting
in three regions internal to and three
regions external to the membrane across the
GN, NSM and GC glycoproteins. The corroboration
of conserved genome domains and
sequence identity among geographically diverse
isolates may assist in the identification
of protein function and pathogenic mechanisms,
as well as the identification of potential
targets for antiviral therapy and vaccine
design. As detailed functional studies are
lacking for many of the CCHFV proteins,
identification of functional domains by prediction
of protein structure, and identification
of amino acid level similarity to functionally
characterised proteins of related viruses or
viruses with similar pathogenic mechanisms are a necessary step for selection of areas for
further study.
