Genome sequencing enables the tracing of ancient infectious diseases and extends to studying animal and plant diseases, aligning with the 'One Health' concept.
What is the ‘Black Death’?
The 'Black Death' was caused by the bacterium Yersinia pestis, discovered separately by Alexandre Yersin and Kitasato Shibasaburō during the Hong Kong plague outbreak in 1894. The disease spreads through fleas or close contact with infected humans or animals. Human-to-human transmission contributed to the large-scale outbreak. While the plague is still a serious disease, it is treatable with antibiotics. India has experienced various plague epidemics, and the plague vaccine was developed in Bombay in 1897. Mass vaccination programs have been implemented in the country, with millions of doses administered to date.
Studying the history of a disease?
The Plague of Justinian in the 6th century A.D. is possibly the earliest documented epidemic, but plague outbreaks likely occurred even earlier. Genetic material from a Swedish tomb suggests plague outbreaks in Asia and Europe during the Late Neolithic-Early Bronze Age. Genome-sequencing technologies now allow scientists to study ancient diseases using well-preserved human remains and advanced computational analysis. Deep-sequencing is used to retrieve degraded DNA from the material.
What has deep-sequencing revealed?
Recent scientific studies have traced the ancient paths of human pathogens, offering valuable insights into their evolution and adaptation. For instance, researchers examined tooth and bone samples, identifying genetic material of Yersinia pestis in five individuals. They reconstructed the pathogen's genome, revealing the absence of certain genes associated with infection-causing abilities. However, they found a functional gene that could make the pathogen toxic to fleas. Another study sequenced genetic material from ancient burial sites in the U.K., identifying Yersinia in three individuals and confirming the presence of epidemics during a specific historical period. This expands our understanding of the geographical spread of infections beyond Eurasia.
What does this tell us about our past?
The absence of certain genes in ancient plague genome sequences suggests that fleas may not have been the primary transmission method during that period. It is believed that the LBNA lineage of Yersinia pestis, which caused the plague, was brought to Europe by human migration from the Eurasian grasslands. The wide geographical spread over time indicates that the plague may have been highly transmissible in the past, but its severity remains uncertain. Genome sequencing has revolutionized outbreak diagnosis, replacing traditional microbiology methods, and providing valuable insights into various aspects of diseases. These technologies now extend to studying animal and plant diseases, contributing to the holistic understanding of 'One Health'.
댓글