Enlarge /. The researchers analyzed the genomes of virus fragments found on smallpox vaccination kits used during the civil war. The kits are in the Mothers Museum of the College of Physicians in Philadelphia.
J.D. Howell / McMaster University
Scientists around the world are currently working feverishly to develop an effective vaccine against COVID-19 to stem the global pandemic that has killed (and counted) nearly 600,000 people worldwide. Meanwhile, a collaboration between scientists from McMaster University, the University of Sydney, and historians from the Mothers Museum in Philadelphia is looking for possible clues in the past. They analyzed the genome of fragments of the pox virus that was used in vaccines during the civil war. This emerges from a new article published in the journal Genome Biology.
"Understanding the history, evolution, and how these viruses can function as vaccines is of tremendous importance these days," said evolutionary geneticist Hendrik Poinar, director of the McMaster Ancient DNA Center, explaining the reasons for the research . "This work shows how important it is to study the diversity of these vaccine strains discovered in the wild. We do not know how many can offer cross-protection against a variety of viruses such as flus or coronaviruses."
The World Health Organization declared smallpox an eradicated disease in 1979, and many people don't remember how devastating it could be. It started with a high fever and severe vomiting, followed by a rash. The victim would next develop wounds that would eventually scratch and fall off and scarred the skin. About three in ten people died, and the survivors were usually scarred for life, sometimes even blind or permanently disabled.
The Chinese vaccinated people against smallpox as early as the 16th century. European doctors relied on variolation (the use of smallpox to induce immunity) at the beginning of the 18th century to control the spread of smallpox, in which scratches from smallpox pustules were scratched in a person's arm or inhaled through the nose. While those receiving treatment often developed smallpox complaints such as fever and rash, the death toll was significantly lower.
Enlarge /. This undated painting by E. Board shows the British doctor Edward Jenner, who on 14 May 1796 carried out his first vaccination against eight-year-old James Phipps.
Bettmann / Getty Images
In the late 1700s, a handful of doctors in England and Germany noticed that people who were infected with the milder cowpox appeared to be immune to smallpox, and there were some early attempts at vaccinating humans. For example, in 1774, a farmer in Dorset, England, named Benjamin Jesty, successfully vaccinated his wife and children with cowpox. But it was the English doctor Edward Jenner who is said to have brought the smallpox vaccine into general medical practice.
Jenner had also noticed that milk girls infected with cowpox were largely immune to smallpox. On May 14, 1796, he scratched the pus of cowpox blisters on the hands of a milk maid named Sarah Nelmes. (The fur of the Blossom cow that gave Nelmes cowpox is on display in the library of St. George's Medical School.) Then he inoculated a boy named James Phipps (his gardener's son) with the scratches, too slight fever. but not a full blown disease. He then exposed the boy to the Variola virus several times, but the young Phipps never developed smallpox. Jenner tested his method on 23 other subjects (including his one-year-old son Robert) before he published his results. Until 1840, the British government had banned variolation and provided the general population with vaccinated cowpox for free.
During the American Civil War (1861-1865), smallpox proved to be a scourge that devastated both Union and Confederate forces. In addition to quarantines and burning infected clothing and blankets, soldiers on both sides of the conflict had to receive smallpox vaccinations to control the spread of the disease. In reality, the requirement to recruit new soldiers has often been ignored, although it still helped contain deadly outbreaks and resulted in widespread smallpox vaccination among American civilians after the war. Crusts were typically harvested from cowpox by infected children, soldiers, and even the cows themselves and sent to army surgeons. (In one notable case, a crust was collected from a young woman of infamous who was also infected with syphilis, spreading the sexually transmitted disease to the soldiers vaccinated with this material.)
According to the authors of this latest study, Philadelphia was the second largest hospital city to serve the influx of sick and wounded soldiers. The Mothers Museum – a true mecca for the morbidly curious – was founded in 1863 to house various medical artifacts and samples for research and teaching, including smallpox vaccination kits and related instruments. The latter included folding lancets, small glass plates for mixing liquids and tin cans to hold scab material. The museum supplied five vaccination kits from the mid to late 19th century for the study. Four kits were leather rollup; The fifth contained a tool known as an "automatic vaccine".
Enlarge /. Co-author Ana Duggan, a former postdoc in the Anthropology Department at McMaster, analyzes a virus sample in the laboratory.
JD Howell, McMaster University
The scientists collected nine samples of virus fragments from the five kits and then reconstructed and analyzed their genomes. (They were even able to extract viral fragments by non-destructively sampling the artifacts that showed no obvious evidence of biological residues.) The goal was to outline the evolutionary relationships of smallpox viruses found in class-era civil war vaccines the poxviruses were used as a whole.
The results showed that a particular virus strain (VACV) was in circulation before the 20th century and was closely related to a commercially produced vaccine strain that was produced in Philadelphia in 1902. In other words, there was very little diversity between the strains used by doctors in the region during the civil war, although vaccines have not been standardized for more than a century.
In addition, the vaccinia strains used for vaccination were distantly related to the virus that causes smallpox. The authors assume that they offer protection against smallpox due to their slow mutation rate. This provides a useful indication of how close a vaccine must be evolutionary to the virus that causes disease to effectively prevent it.
The researchers also found similarities between the construction of the kits – which were tailor-made (bespoke) and not available in catalogs at the time – and their content. "It was well known how vaccinations were practiced at this particular time," they concluded. "Indeed, the similarity of virus strains, not just these five civil war kits, but also the 1902 tribe, suggests that there may have been a common source of material in the Philadelphia region."
The authors believe that their work paves the way for a new non-destructive approach to medical history studies. "Vaccination is a wonderful process with a rich medical history to celebrate," said co-author Ana Duggan, who is now with the Canadian public health agency. "Medical museums are incredible repositories of our past and our collective history. With the new tools we develop in this work, we can examine how medical sources, procedures and techniques have changed over time."
DOI: Genome Biology, 2020. 10.1186 / s13059-020-02079-z (About DOIs).