[Sequencing and comparative analysis of the complete glycoprotein gene of three Crimean-Congo hemorrhagic fever virus Chinese isolates].
OBJECTIVE
To determine the complete sequences of glycoprotein (M) gene of Crimean-Congo hemorrhagic fever virus (CCHFV) Chinese isolates (Xinjiang hemorrhagic fever virus, XHFV) BA66019, BA8402 BA88166 and to compare and analyze the relationships among the viruses.


METHODS
Based on the conserved reverse complementarity of the CCHFV genomic termini, a primer PCM-Tag was designed and used together with random hexmers to initiate reverse transcription of viral RNA to synthesize cDNA. The latter was amplified with single primer PCM-Tag using the proof-reading DNA polymerase to produce the complete M gene. The PCR products were gel-purified and the whole M segment was sequenced and the comparison and analysis were performed aided by computer for the phylogenesis and coding strategy.


RESULTS
Comparison of the whole M gene sequences of XHFV reference strain BA66019 with international prototype CCHFV IbAr10200 showed an excess of 5 base pairs in length, resulting in 5,365 bp; while BA8402 and BA8816 are 5,365 bp long, 4 more base pairs than IbAr10200. The first start codons of long ORFs were located at the 78th base pair in M gene of BA66019, BA8402 and BA88166, which were 15 base pairs prior to that of IbAr10200. The precursors encoded by these M genes were totaled 1,689 amino acids (AA), 6 AAs more than that of IbAr10200. The similaries between CCHFV M genes in nucleotide level were: 80.9% (IbAr10200-BA66019), 80.2% (IbAr10200-BA8402), 80.2% (IbAr10200-BA88166), 83.7% (BA8402-BA66019), 83.6% (BA88166-BA66019), and 99.0% (BA8402-BA88166), respectively. The corresponding similarities in amino acid level were 85.1%, 86.3%, 86.6%, 87.8%, 88.0%, and 98.8%, respectively. The similarities of M genes of CCHFVs and Dugbe virus in both nucleotide and amino acid levels were around 55% and 37%, which were much lower than those among CCHFVs.


CONCLUSIONS
The M genes of XHFVs and IbAr10200 formed respective independent phylogenetic branches genetically and the human-origin isolate BA88166 might be a variant of tick-borne BA8402, suggesting that there was only one kind virus prevailing in Xinjiang epidemic areas in 1980s.
Ma
B
B
Institute of Virology, Chinese Academy of Preventive Medicine, Beijing 100052, China.
Hang
C
C
Papa
A
A
D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002681:China; D006023:Glycoproteins / Q000737:chemistry / Q000235:genetics*; D003225:Hemorrhagic Fever Virus, Crimean-Congo / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D017385:Sequence Homology
D006023:Glycoproteins