Vaccination of koalas with a prototype chlamydial vaccine is safe, does not increase the incidence of lymphoma-related disease and maybe associated with increased lifespan in captive koalas. Issue 36 (26th August 2015)

• Record Type: Journal Article
• Authors: Hernández-Sánchez, Jules; Brumm, Jacqui; Timms, Peter; Beagley, Kenneth W.
• Is Part Of: Vaccine. Volume 33:Issue 36(2015)
• Page Start: 4459
• Page End: 4463
• Publication Date: 2015-08-26
• Subjects: Vaccines -- Periodicals; 615.372
• DOI: 10.1016/j.vaccine.2015.07.029
• Languages: English
• ISSNs: 0264-410X

Abstract

<abstract abstract-type="author" id="abs0005"> <title id="sect0005">Abstract</title> <sec> <title id="sect0010">Objectives</title> <p id="spar0005">To assess the impact of <italic>Chlamydia</italic> vaccination on survival of captive koalas, and to compare the incidence of lymphomas and neoplasias between vaccinated and unvaccinated koalas.</p> </sec> <sec> <title id="sect0015">Methods</title> <p id="spar0010">Survival analysis using Cox and Weibull regressions on 54 vaccinated and 52 matched unvaccinated koalas, and chi-square contingency table for incidence of lymphomas/neoplasias.</p> </sec> <sec> <title id="sect0020">Results</title> <p id="spar0015">Vaccination was found to have a significant positive effect on koala lifespan (<italic>P</italic> = 0.03), with vaccinated koalas having a median lifespan of 12.25 years compared to 8.8 years for unvaccinated ones. The effect of sex on lifespan was not significant (<italic>P</italic> = 0.31). The risk ratio of unvaccinated over vaccinated koalas was 2.2 with both Cox and Weibull regressions. There was no association between the incidence of lymphoma/neoplasias and vaccination status (<italic>P</italic> = 0.33).</p> </sec> <sec> <title id="sect0025">Conclusions</title> <p id="spar0020">Koalas vaccinated with a prototype <italic>Chlamydia</italic> vaccine may live longer than unvaccinated ones. There was no known <italic>Chlamydia</italic> infection among koalas, so our interpretation is that vaccination may have boosted the innate and adaptive immune systems to protect against a wide spectrum of bacteria, fungi and parasites. Vaccinated koalas did not show negative physiological effects of the vaccine, for example, the frequency of deaths due to lymphomas/neoplasias was the same in both vaccinated and unvaccinated animals.</p> </sec> </abstract>