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Genome Structure of Hemorrhagic Fever Virus

#1291


Study of the Genomic Structure of Crimean-Congo Hemorrhagic Fever Virus Isolates Circulating in the Southern Regions of NIS Countries

Tech Area / Field

  • MED-DIS/Disease Surveillance/Medicine
  • MED-DID/Diagnostics & Devices/Medicine
  • BIO-CGM/Cytology, Genetics and Molecular Biology/Biotechnology

Status
8 Project completed

Registration date
28.05.1998

Completion date
05.06.2001

Senior Project Manager
Nietzold D

Leading Institute
State Research Center of Virology and Biotechnology VECTOR / Institute of Molecular Biology, Russia, Novosibirsk reg., Koltsovo

Supporting institutes

  • Ivanovsky Institute of Virology, Russia, Moscow

Collaborators

  • USAMRIID, USA, MD, Fort Detrick\nCenters for Disease Control and Prevention (CDC), USA, GA, Atlanta

Project summary

The etiologic agent of CCHF is a group of related viruses that are borne by arthropods (ticks) and vertebrates. People usually get infected if bitten by infected ticks living on the blood of various animals, and the mortality rate here makes 30 to 50 percent. Factors leading to the outbreak of this disease have not been given a satisfactory explanation until now.

The CCHF, although irregular and focal, is remarkably widespread. The CCHF virus circulates throughout many of the southern NIS countries, Central Asia, Southern Europe, the Middle East, and Africa. In spite of that first it was discovered in the Soviet times on the territory of the former Soviet Union, no data available on the genome structures of viral isolates currently circulating on the territories of the NIS countries.

Currently, there is no satisfactory diagnostic method for CCHF and this problem will not be resolved until the sequence of the M segment of viral RNA has been determined because it is the M RNA segment that encodes viral surface glycoproteins that provide for immune response in animals.

From this perspective, substantial research efforts are required to improve the existing diagnostic procedures for CCHF virus; to establish a distribution pattern of this virus in the NIS countries and clarify its antigenicity and the antigenic properties of recombinant CCHF viral proteins.

We have more than thirty strains of CCHF virus in our research team’s collection. Academician Lvov and his colleagues isolated and characterized these strains of CCHF virus from ticks and humans in 1970-1991 years.

Also, we have several strains of the virus in the collection of the Research Institute of Molecular Biology that were obtained from Dr. Vassilenko (Bulgaria) and Academician Lvov (member of our research team). The Russian research teams have considerable experience with the CCHF virus and are conveniently located to each other which will ensure close collaboration between these teams on all aspects pertaining to work on the virus. Dr. Petrov and colleagues will develop recombinant E.coli and viral-vectored strains expressing structural proteins of isolated strains of the CCHF virus. The expressed proteins will be characterized in ELISA tests to identify the most suitable recombinant proteins for detecting CCHF virus-specific antibodies in human and animal sera. Academician Lvov and colleagues will isolate and identify various strains of CCHF virus found in different regions of Southern Russia and the NIS countries. They will help with the development of recombinant viruses and characterization of their reactivity in ELISA tests. They will look for evidence of the CCHF virus and antibodies in natural species obtained from ticks and humans in the FSU.

Objectives of the Project:

1. Distribution of the CCHF virus in southern regions of the NIS countries. To isolate and identify the CCHF virus from patients and animals by serological, virology, and hybridization methods.

2. Virus persistence. To look for evidence of persistent CCHF virus infections in animals by the detection of antibodies and viruses in healthy and chronically ill animals.

3. Virus antigenicity. To sequence the nucleocapsid gene of CCHF virus obtained from ticks and humans from different southern regions of the NIS countries. To compare these sequencing data with those published in literature. These data will be used to look for evidence of common domains that may determine the antigenic characteristics of the viruses.

4. Primary structure of the M segment. To determine the nucleotide sequence of the CCHF M RNA gene segment and then produce recombinant E. coli-vectored strains that express viral surface proteins.

5. Development of a method for reliable CCHF diagnosis. To produce CCHF-encoded proteins as expression products of the E.coli-vectored strains and recombinant viruses that can be used in ELISA tests to detect CCHF antibodies in human or animal sera. To examine recombinant proteins in ELISA tests whether they can or not detect and distinguish the CCHF antibodies in human sera.

5.1. To test the recombinant proteins for their ability to interact with a panel of standard antibodies against CCHF virus.
5.2. To produce a pilot series of a new enzyme immunoassay system for the detection of antibodies to CCHF virus in clinical specimens.


It is known that diagnosis of this virus becomes difficult because in nature there exist several species of antigenically related viruses of the Nairovirus genus. Unlike other bunyaviruses, the CCHF virus and other representatives of this genus are not well-studied.

Subsequently, our goal is to develop a method for identification of the CCHF virus in clinical samples using recombinant bacterial or viral strains expressing antigens of CCHF virus and to introduce this method into wider clinical practice.

Expected Results:

1. To obtain the data on geographic distribution of CCHF virus on the territories of the NIS countries and on types of hosts who can be naturally infected.

2. To obtain results for evidence of persistent CCHF virus infections in animals by detection of antibodies and virus in healthy and chronically ill animals.

3. Virus antigenicity. To sequence the nucleocapsid gene of CCHF virus obtained from ticks and humans from different southern regions of the NIS countries. To compare these sequencing data with those published in literature. These data will be used to look for evidence of common domains that may determine the antigenic characteristics of the viruses.

4. Primary structure of the M segment. To determine the nucleotide sequence of the CCHF M RNA gene segment and then produce recombinant E. coli-vectored strains that express viral surface proteins.

5. Development of a method for reliable CCHF diagnosis. To produce CCHF-encoded proteins as expression products of the E.coli-vectored strains and recombinant viruses that can be used in ELISA tests to detect CCHF antibodies in human or animal sera. To examine recombinant proteins in ELISA tests whether they can or not detect and distinguish the CCHF antibodies in human sera.

5.1. To test the recombinant proteins for their ability to interact with a panel of standard antibodies against CCHF virus.
5.2. To produce a pilot series of a new enzyme immunoassay system for the detection of antibodies to CCHF virus in clinical specimens.


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