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Genetic characterization of wild-type measles viruses circulating in suburban Khartoum, 1997-2000
H S El Mubarak1,2, M W G van de Bildt2, O A Mustafa1
1Institute of Endemic Diseases, University of Khartoum, PO Box 102, Khartoum, Sudan2.
Abstract:
Measles remains endemic in many East African countries, where it is often associated with high morbidity and mortality. We collected clinical specimens from Sudanese measles patients between July 1997 and July 2000. Sequencing of the 3' 456 nucleotides of the nucleoprotein gene from 33 measles virus (MV) isolates and 8 RNA samples extracted from clinical specimens demonstrated the presence of a single endemic MV strain with little sequence variation over time (overall nucleotide divergence of 0 to 1.3%). This was confirmed by sequencing of the complete H gene of two isolates from 1997 and two from 2000, in which the overall divergence ranged between 0 and 0.5%. Comparison with MV reference strains demonstrated that the viruses belonged to clade B, genotype B3, and were most closely related to a set of viruses recently isolated in Nigeria. Our study demonstrates a remarkable genetic stability of an endemically circulating MV strain.
Insights
Measles virus (MV) circulating in Sudan between 1997-2000 showed remarkable genetic stability. This endemic strain, belonging to genotype B3, exhibited minimal sequence variation over three years.
Area of Science:
- Virology
- Epidemiology
- Public Health
Background:
- Measles is a significant public health concern in East Africa, causing substantial morbidity and mortality.
- Understanding the genetic diversity of endemic measles virus (MV) strains is crucial for effective control strategies.
Purpose of the Study:
- To investigate the genetic characteristics and temporal variation of measles virus (MV) strains circulating in Sudan.
- To determine the phylogenetic relationship of Sudanese MV isolates to other global strains.
Main Methods:
- Nucleotide sequencing of the nucleoprotein (N) gene (3' 456 nt) and the complete hemagglutinin (H) gene of 33 MV isolates and 8 RNA samples.
- Phylogenetic analysis to compare sequence variation and determine MV clade and genotype.
Main Results:
- A single endemic MV strain was identified in Sudan with low genetic variability (0-1.3% nucleotide divergence in the N gene).
- Sequencing of the H gene confirmed this genetic stability (0-0.5% divergence).
- The Sudanese MV isolates belonged to clade B, genotype B3, and were closely related to Nigerian isolates.
Conclusions:
- The study highlights the remarkable genetic stability of the endemic measles virus (MV) strain in Sudan over a three-year period.
- This genetic conservation suggests a stable endemic circulation pattern of MV genotype B3 in the region.