A 2010 study determines the origin of the measles virus coming from the 11th to 12th century. However, a more recent study published in the journal Science says the virus emerged as early as the 6th century BCE.
This new finding is based on a virus sample collected from a century-old lung preserved in formalin dating back to 1912. Scientists were amazed at how easily they obtained the virus sample, considering the amount of time it had been preserved.
Measles is considered to be a highly contagious and infectious disease. Although vaccination is made available, the condition still poses a tremendous burden on human health.
In 2018, about 144,000 people died from the disease. Many of these casualties came from unvaccinated individuals. Measles is one of the diseases that originated from animals. It is believed to be caused by a spill-over of the virus from cattle to humans.
The Century-Old Diseased Lung
A collaborative team of researchers from the University of Oklahoma, and the University of California in Los Angeles, KU Leuven, the Robert Koch Institute, and the Berlin Museum of Medical History at the Charité analyzed samples from the said century-old lung. The lung belonged to a two-year-old measles patient who died in 1912 in Berlin.
The lung had been kept on display at the Berlin Museum of Medical History and was preserved in formalin. RNA molecules that make up the genetic material of a virus typically disintegrate easily. But surprisingly, the team was able to assemble the entire measle virus genome from the old diseased lung quite easily.
The measles virus found in the century-old diseased lung is not known as the oldest human-infecting RNA virus sequence to date. According to Sébastien Calvignac-Spencer of the Robert Koch Institute, the team was excited to find that recovering viral RNA from such an ancient specimen was possible and somewhat easy to do.
Molecular Dating of the Measles Virus
After obtaining the viral sequence, the 1912 genome was then added to a dataset of other genomic data. The researchers combined the genome to strains of the measles virus, rinderpest, and ovine rinderpest viruses.
Based on the data they had and using a new approach for advanced molecular clock modelling, the researchers were able to reassess the divergence date of the rinderpest and measles viruses.
Their calculation places the moment of divergence into the 6th century BCE. This period was marked by booming populations and the rise of large cities both in Asia and Europe.
According to Kyle Harper, a historian from the University of Oklahoma, although there is no direct proof that measles appeared in humans shortly after divergence, the plausible scenario cannot be ignored.
Philippe Lemey, an evolutionary virologist at KU Leuven and one of the senior authors of the study says that one of the oldest mentions of measles has been dated from around the 10th century. However, earlier reports have claimed epidemics in bovine and human populations started even way before.
The researchers hope that their study and other future research will help scientists in understanding how these events might be linked to the measles virus.
