036 - Effect of Calmette's BCG Vaccine on Experimental Animals

Back in 1929, there wasn't a very good vaccine against tuberculosis, though many people (including famous ones) had tried to make one. The one that seemed to have the most potential was called BCG, or Bacillus Calmette-Guérin, discovered by Calmette and others. (Modernity note: the situation hasn't really changed much since then. BCG is still the TB vaccine of choice, and doesn't work very well. Used sometimes in countries with endemic TB, not in the USA.) This is made from a strain isolated from a cow, and is the bovine version of tuberculosis, so isn't very virulent for other species (or for cows either, apparently). And after Calmette grew it in the lab for a while, it was even less virulent.

Calmette had tried it in thousands of infants since 1921, but hadn't kept good records, so the results are unavailable, unfortunately. But it seemed to produce mild TB consistently in lab rodents, thus protecting them from more serious disease.

This study tried to clarify some of the methods and results using the BCG vaccine in several kinds of animals.  Specifically: guinea pigs, calves, and monkeys, inoculated orally, subcutaneously, or intraperitoneally (near the organs).

Feeding BCG to animals generally didn't work very well: pigs and calves didn't show any tubercles indicative of tuberculosis response, though almost half the monkeys they tested did. And animals challenged with a virulent strain of TB after oral BCG vaccine got TB almost as much as controls, especially pigs and monkeys.

Subcutaneous vaccination worked a bit better. Many pigs showed tubercles and one may even have died from it; most monkeys and calves also showed an effect. Generally it was mild though. When challenged with a virulent strain, vaccinated guinea pigs generally had milder TB (or none at all) compared to controls; similar with monkeys, and I couldn't really tell with calves. So I guess that's a positive result, if it's the best you can get.

They got similar results with intraperitoneal vaccination in pigs, though the vaccine seemed rougher for them. But they seemed to have a little protection.

Overall, it didn't seem like great results, but it wasn't a great study.

Citation: King, M. J. & Park, W. H. Effect of Calmette’s BCG Vaccine on Experimental Animals. Am J Public Health Nations Health 19, 179–192 (1929).