New world origin of canine distemper: Interdisciplinary insights.

OBJECTIVE: Canine distemper virus (CDV), human measles virus (HMV), and rinderpest virus (RPV) of cattle are morbilliviruses that have caused devastating outbreaks for centuries. This paper seeks to reconstruct the evolutionary history of CDV. MATERIALS AND METHODS: An interdisciplinary approach is adopted, synthesizing paleopathological analysis of 96 Pre-Columbian dogs (750-1470 CE) from the Weyanoke Old Town, Virginia site, with historical reports, molecular analysis and morbilliviral epidemiology. RESULTS: Both measles (c.900CE) and rinderpest (c. 376 BCE) were first reported in Eurasia, while canine distemper was initially described in South America much later (1735 CE); there are no paleopathological indications of CDV in Weyanoke Old Town dogs. Molecularly, CDV is closely related to HMV, while viral codon usage indicates CDV may have previously infected humans; South American measles epidemics occurred prior to the emergence of canine distemper and would have facilitated HMV transmission and adaptation to dogs. CONCLUSIONS: The measles epidemics that decimated indigenous South American populations in the 1500-1700 s likely facilitated the establishment of CDV as a canine pathogen, which eventually spread to Europe and beyond. SIGNIFICANCE: Understanding the historical and environmental conditions that have driven morbilliviral evolution provides important insights into potential future threats of animal/human cross-species infections. LIMITATIONS: Interpreting historical disease descriptions is difficult and the archaeological specimens are limited. Molecular sequence data and codon usage analyses rely on modern viruses. SUGGESTIONS FOR FURTHER RESEARCH: Interdisciplinary approaches are increasingly needed to understand diseases of the past and present, as critical information and knowledge is scattered in different disciplines.

The evolutionary history of dogs in the Americas.

Dogs were present in the Americas before the arrival of European colonists, but the origin and fate of these precontact dogs are largely unknown. We sequenced 71 mitochondrial and 7 nuclear genomes from ancient North American and Siberian dogs from time frames spanning ~9000 years. Our analysis indicates that American dogs were not derived from North American wolves. Instead, American dogs form a monophyletic lineage that likely originated in Siberia and dispersed into the Americas alongside people. After the arrival of Europeans, native American dogs almost completely disappeared, leaving a minimal genetic legacy in modern dog populations. The closest detectable extant lineage to precontact American dogs is the canine transmissible venereal tumor, a contagious cancer clone derived from an individual dog that lived up to 8000 years ago.