This is prompted by an article in my local newspaper article about an immunologist who was talking to grade 5 students about immunization. One of the kids asked her if snakes could get vaccinated, which stumped her. After talking to a colleague, she reported back that immunisations are not recommended for snakes. I think a snake could be immunised - they have a blood system, and presumably antibodies. I thought I would go to the folks who might know! Theoretically, could a snake be immunised?
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I’m no snake epidemiologist (wow, that’s something I never thought I’d say). But I assume they could feasibly be immunized against viral diseases that exclusively affect snakes. The presence of antigens that normally wouldn’t be present in snake systems, or react to snake cells, might very well trigger a disproportionately adverse immune response.
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Antibodies are produced by B cells in response to exposure to an antigen. Reptiles have B cells and produce antibodies in response to antigens, so I don’t see why vaccines wouldn’t work in a snake.
I found a paper that says:
“Overall, in comparison to mammals, the reptile antibody response is weaker [22] since the titres do not necessarily increase after a second antigen exposure and there is a lack of affinity maturation [21,22]. However, studies on colubrid snakes indicated an increase in titres after repeated antigen exposure [40], and the rapidness of the response indicates immunological memory [21,22,40]. Again, the reptile antibody response is affected by environmental and individual factors such as temperature, season, sex, age, and the neuroendocrine status [14,22].”
And then I found this paper, published this year, which confirms my hunch:
“There are currently no vaccines against reptarenaviruses, although an effective vaccine might allow reptarenavirus eradication and enable BIBD-free snake collections. Because UGV-like viruses appear to dominate in BIBD-positive animals (11, 13, 16), future studies should address the possibility of vaccinating snakes using either inactivated UGV or recombinant NP of UGV. They should also determine the virus dose suitable for vaccine challenge experiments.”
https://journals.asm.org/doi/full/10.1128/JVI.01968-20
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This is a great question with really deep implications – most of which I don’t understand! But in general, as I understand it, response to vaccinations is the kind of adaptive immunity exhibited by vertebrate animals and not other forms of life.
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Reptile vaccines, likely costly to develop. Interesting, there is no lymph nodes, but they do have ‘lymph hearts’. That’s a new one to me. Mammals & Birds have higher evolved lymphatic systems w/ vessels pumping lymph. Reptiles definitely have nasty bacteria filled mouths, as well as venoms injected during territorial & mating fights. They evolved immunities to these specific challenges.
Scientists say that’s because the blood of Komodo dragons is filled with proteins called antimicrobial peptides, AMPs, an all-purpose infection defense produced by all living creatures, that one day may be used in drugs to protect humans.Oct 6, 2017
Immunology of Reptiles
Francesca M Rios Laura M Zimmerman
First published: 15 October 2015
https://onlinelibrary.wiley.com/doi/abs/10.1002/9780470015902.a0026260
Cold Spring Harb Perspect Med v.2(4); 2012 Apr
The New Era of the Lymphatic System: No Longer Secondary to the Blood Vascular System
Inho Choi Sunju Lee Young-Kwon Hong
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@rbrtmck1962 Welcome to the Forum! @schizoform It takes a grade 5 student to ask great questions!
Thank you for the responses - they have been very helpful.
If there is a snake rehab, wildlife shelter, nearby? They would have a practical management answer. It would likely only be an issue if many snakes are confined close together in captivity?
Or where snakes are kept to harvest antivenom? Australia?
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Not that I know of. But interestingly garter snakes congregate inside small caves just north of here for the winter. I do not know if there is viral transmission among them. I know little about snakes at all!
In general, squamates rely much more on an innate immune response than an adaptive immune response. They do show adaptive production of antibodies in response to exposure to pathogens, but the primary response takes much longer than in mammals, over 6 months in some cases. They also may not show much immunological memory (ie, making antibodies due to repeated exposures to a pathogen), though this varies. There’s still a ton we don’t know about adaptive immunity in reptiles (partially because the weaker, slower response makes it harder to study). But given these characteristics, it seems likely that vaccinations would be less effective in squamates than in mammals, though potentially possible, simply because the overall response is slower and weaker.
Some good (but paywalled) references:
https://www.journals.uchicago.edu/doi/pdf/10.1086/700396
https://link.springer.com/chapter/10.1007/978-3-319-76768-0_20
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from a practical standpoint, developing vaccines for snakes would be very expensive and for what benefit? a VERY strong need, indeed, would need to arise in order to do something that would otherwise be very costly.
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That was my thought at first also. But there seems to be enough interest in Boid inclusion body disease in boas and pythons that at least one group has attempted vaccination:
https://www.biorxiv.org/content/10.1101/2020.10.05.327502v1.full
https://www.vetpathology.uzh.ch/de/forschung/Infektionskrankheiten-bei-Reptilien/BoldInclusionBody.html
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The first article seems to be available for free on ZLibrary, if such is a resource is one you’re willing to use.
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Thank you all for the responses - I have learned far more about reptilian immunity than I ever imagined. I’m basically an insect person! I have written to the Dr. with most of what I have learned, and she responded that her answer to the student was more nuanced than that reported. I am so grateful to belong to an online community where I can ask such arcane questions, and get answers from people who know far more than me!
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Just a little addition to a great discussion. There are several known cases when autovaccination was partially effective against various pathogens in reptiles.
First one is the vaccination against Mycoplasma crocodyli in crocodile farms that is known since late 1990s: Mohan et al. (2001) Vaccination to control an outbreak of Mycoplasma crocodyli infection. Autovaccines also have been used against Crocodile pox.
Relatively recent research showed that auvaccination provides partial protection against Devriesea agamarum associated disease in bearded dragons: Hellebuyck et al. (2014) Autovaccination Confers Protection against Devriesea agamarum Associated Septicemia but Not Dermatitis in Bearded Dragons (Pogona vitticeps).
Autovaccine was also effective in treatment of Herpesvirus associated dermal papillomatosis in Williams’ mud turtle: Široký et al. (2018) Herpesvirus associated dermal papillomatosis in Williams’ mud turtle Pelusios williamsi with effects of autogenous vaccine therapy.
I’ve also read about the supposedly effective autovaccinations against Herpesvirus associated diseases in marine turtles, but with no scientific data provided. On the other hand an attemt to use vaccine against Herpesvirus in Mediterranean tortoises (Testudo sp.) has failed and there was no rise in antibody titer in vaccinated animals: Marschang et al. (2001) Virus isolation and vaccination of Mediterranean tortoises against a chelonid herpesvirus in a chronically infected population in Italy.
If we talk specifically about snakes there is a report on experimental vaccination against Reptilian ferlavirus (aka Ophidian paramyxovirus) in rattlesnakes. The antibody responses in animals were variable and transient, therefore vaccination currently could not be used for prevention or treatment of ferlavirus infection in snakes. Jacobson et al. (1991) Antibody responses of western diamondback rattlesnakes (Crotalus atrox) to inactivated ophidian paramyxovirus vaccines.
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