Genetic heterogeneity of the foot-and-mouth disease virus Leader and 3C proteinases

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The past, present and future of foot-and-mouth disease vaccinology: A Literature Review

Foot-and mouth disease (FMD) is a highly contagious acute viral infection, affecting all cloven-hoofed animals. Its host range in domestic animals include cattle, sheep, goats and pigs, while a number of wild life species such as antelope, both water and African buffalo, camels, llama and giraffe are also susceptible. Although mortality rates are generally low (less than 5%), FMD has a major economic impact on the livestock industry. The direct losses are mainly due to reduced production of meat, milk and other animal products during an outbreak. Spread of the disease is usually rapid with a short incubation period of± 2 to 8 days (Thomson, 1994).
Transmission of the disease is either direct or indirect. The most general route is direct contact between infected animals that excrete the virus, and susceptible animals. FMD virus is present in all secretions and aerosols derived from the respiratory tract during the infectious period. Indirectly, the disease can be transmitted by viral contaminated objects or materials, such as tissues and animal products (e.g. milk and meat), while humans and vehicles have also been implicated in the mechanical transmission thereof (Sellers, 1971). Although airborne transmission occurs very rarely and is very much dependent on climate, several outbreaks occurring by this means have been reported in northern Europe (Donaldson, 1979; Fogedby et ai., 1960; Gloster et ai., 1982).
The FMD virus can persistently infect ruminants for periods ranging from a few weeks to years. In such cases, virus can be isolated from the oesophagus and throat fluids by probang extractions (van Bekkum et ai., 1959). In cattle, this carrier status has been shown to be responsible for outbreaks of the disease up to two years post infection (Thomson, 1996). The African buffalo (Syncerus caffer), known to maintain the virus for five years in an individual animal and at least 24 years in an isolated herd (Condy et al., 1985), can transmit the disease to cattle (Hedger & Condy, 1985; Dawe et aI., 1994; Vosloo et al., 1996). The mechanism of transmission is however not clearly understood, but recent reports indicate that sexual transmission of the disease between buffalo and cattle is a possibility (Bastos et aI., 1999).

Chapter 1: The past, present and future of foot-and-mouth disease vaccinology: A literature Review
1.1. General Introduction
1.2. A historical perspective of foot-and-mouth disease outbreaks
1.3. Foot-and-mouth disease virus properties
1.3.1 Classification
1.3.2 Physical properties
1.3.3 Genome organization and viral structure
1.3A Overvie »w ofirifectious cycle
1.3.5 Antigenic properties
1.4. Vaccination against foot-and-mouth disease
1.4.1. Conventional, inactivated vaccines
1.4.1.1. FMD viral production in cell lines
lA.l.2. Inactivation of fMDV
lA.l.3. Vaccineformulatioll
lA.2. Alternative vaccines
lA.2.1. Heterologous gene expression
1. -1.2.2. DNA vaccination
1.-1.2.3. Synthetic peptide vaccines
1.5. Vaccination in sub-Saharan Africa – Aim and Scope of project
Chapter 2: Molecular characterization of the structural-protein-coding region of ZIM17/83/2, a SAT 2 type foot-and-mouth disease virus
2.1 Introduction
2.2 Materials and Methods
2.2.1 Viral and bacterial strains
2.2.2 Oligonucleotides
2.2.3 Partial pur[ficatioll ~fviruses and RNA extraction
2.2A cDNA synthesis
2.2.5 PCR amp/~fication
2.2.6 TA cloning
2.2.7 Nucleotide sequencing and analysis
2.3 Results and Discussion
2.3. J Cloning and characterization oflIM7/832 PJ
2.3.2 Comparison oflIM17/8Y2 P J with known P J regions
2.3.3 Identification ofhypervariable regions }1/ithin the SAT 2 serotype
2.3.4 Description oflIM’JI83!2 cleavage sites
2.4 Conclusions
Chapter 3: Genetic heterogeneity of the foot-and-mouth disease virus Leader and 3C proteinases
3.1 Introduction
3.2 Materials and Methods
3.2. J Viruses investigated
3.2.2 RNA extraction, cDNA synthesis and PCR amp/[fjcation
3.2.3 Nucleotide sequence determination and analysis
3.2.4 Determination ofgene relationships for FMDV Lab and 3 proteinases coding regions
3.2.5 Structural modeling ofFMD V Lb proteinase
3.2.6 Determination ofFMDV P J cleavage sites mediatedby the 3C proteinase
3.3 Results and Discussion
3.3. J Gene heterogeneity and gene relationships ~fLab proteinases
3.3.2 Structural modelfor lIM/7183!2 Lb proteinase
3.3.3 Gene heterogeneity and gene relationships of3Cproteinases
3.3.4 Comparison ofFMDVPI cleavage sites mediated by the 3C proteinase
3.4 Conclusions
Chapter 4: Construction of a chimeric foot-and-mouth disease virus between serotypes A and SAT 2: Comparison with wild type SAT in terms of antigenicity, growth properties and thermal stability
4.1 Introduction
4.2 Materials and Methods
-1.2.1 Viral and bacterial strains
-1.2.2 RNA extraction and cDNA synthesis
-1.2.3 PCR amplification
4.2.-1 Cloning ofSAT 2 external capsid coding region into Al2 jl?fectiolls cDNA clone
-1.2.5 RNA synthesis
4.2.6 Transfection ofBHK cells with infectious viral RNA
4.2.7 Viral titratiollS on IB-RS-2 cells
4.2.8 Plaque titrations all IB-RS-2 and BHK cells -1.2.9 Virus neutralization test
4.2. J0 Determination ~f J46S content
4.2.11 Determination ofgrowth kinetics
4.2.12 Thermal stability testing
4.3 Results and Discussion
4.3.1 Construction ofa chimeric virus between serotypes A and SAT 2
-1.3.2 Comparison with wild type SAT 2
4.3.2.1 Immunogenicity
4.3.2.2 Growth properties and antigen production
-1.3.2.3 Thermal stability
4.4 Conclusions
Chapter 5: Concluding remarks: What does the future hold?
References
List of Congress Contributions 1
List of published papers