A 5-year Chlamydia vaccination programme could reverse disease-related koala population decline: Predictions from a mathematical model using field data

Craig, Andrew P.; Hanger, Jon; Loader, Jo; Ellis, William; Callaghan, John; Dexter, Catherine; Jones, Darryl; Beagley, Kenneth W.; Wilson, David

doi:10.1016/j.vaccine.2014.05.049

Cited by 16 publications

(18 citation statements)

References 29 publications

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“…Mathematical modeling has been invaluable in determining the attributes a vaccine must possess in order to impact on infection transmission. 5,26 Assertions that non-sterilizing vaccines, if targeted toward both sexes, could interrupt infection transmission had not yet been investigated experimentally. 5 Challenging female mice with prostatic fluids collected from infected males to model sexual transmission (Figure 9a), we determined that the immunization status (immunized or unimmunized) of both sexes was critical for the Figure 6 Gene expression in whole oviducts, macrophages, neutrophils, Tc, and Th cells isolated from the oviducts following immunization and challenge with a sexually transmissible dose of C. muridarum.…”

Section: Discussionmentioning

confidence: 99%

Induction of partial immunity in both males and females is sufficient to protect females against sexual transmission of Chlamydia

et al. 2016

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Sexually transmitted Chlamydia trachomatis causes infertility, and because almost 90% of infections are asymptomatic, a vaccine is required for its eradication. Mathematical modeling studies have indicated that a vaccine eliciting partial protection (non-sterilizing) may prevent Chlamydia infection transmission, if administered to both sexes before an infection. However, reducing chlamydial inoculum transmitted by males and increasing infection resistance in females through vaccination to elicit sterilizing immunity has yet to be investigated experimentally. Here we show that a partially protective vaccine (chlamydial major outer membrane protein (MOMP) and ISCOMATRIX (IMX) provided sterilizing immunity against sexual transmission between immunized mice. Immunizing male or female mice before an infection reduced chlamydial burden and disease development, but did not prevent infection. However, infection and inflammatory disease responsible for infertility were absent in 100% of immunized female mice challenged intravaginally with ejaculate collected from infected immunized males. In contrast to the sterilizing immunity generated following recovery from a previous chlamydial infection, protective immunity conferred by MOMP/IMX occurred independent of resident memory T cells. Our results demonstrate that vaccination of males or females can further protect the opposing sex, whereas vaccination of both sexes can synergize to elicit sterilizing immunity against Chlamydia sexual transmission.

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Section: Discussionmentioning

confidence: 99%

Induction of partial immunity in both males and females is sufficient to protect females against sexual transmission of Chlamydia

et al. 2016

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“…Inclusion criteria stipulated that animals must be males of breeding age (>2 years old), clinically healthy, and had not been enrolled in, nor had a mother that had been enrolled in a previous vaccine trial. 12 koalas that met the aforementioned criteria were enrolled in the study and assigned at random to each group. All procedures were approved by the Queensland University of Technology (QUT) Animal Ethics Committee (approval number 1000000638).…”

Section: Animalsmentioning

confidence: 99%

“…What is clear is that antibiotics alone are not sufficient to affect a cure and/or maintain healthy populations. Recent modeling on a koala population in QLD has suggested that for a range of anti-chlamydial vaccine efficacy levels the population decline due to Chlamydia could be reversed in just 5 years, but a vaccination schedule will likely need to be ongoing to maintain low Chlamydia prevalence [12]. Thus, we propose that a vaccine will provide an important conservation management tool for this species.…”

Section: Introductionmentioning

confidence: 97%

Comparison of subcutaneous versus intranasal immunization of male koalas (Phascolarctos cinereus) for induction of mucosal and systemic immunity against Chlamydia pecorum

Waugh

Andrew

Rawlinson³

et al. 2015

Vaccine

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“…Koalas are also infected by KoRVs, trypanosomes, and herpesviruses, but impacts on survival and fecundity are poorly understood (Denner & Young, ; McInnes, Gillett, Hanger, Reid, & Ryan, ; Vaz et al., ). While infectious disease has been suggested as a significant, perhaps dominant, factor in drastic declines (and in some instances, local extinction) of many koala populations (Craig et al., ; Rhodes et al., ), the role of chlamydial disease and retroviral infection of koalas as fundamental drivers of population decline remains unclear (White & Timms, ).…”

Section: Introductionmentioning

confidence: 99%

Assessing the significance of endemic disease in conservation—koalas, chlamydia, and koala retrovirus as a case study

McCallum

Kerlin

Ellis

et al. 2017

CONSERVATION LETTERS

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It can be difficult to establish the conservation significance of endemic infectious diseases-those that are well established in a population-in contrast with infectious diseases that are still invading. This difficulty can have important implications for designing policy to address species declines. The infectious diseases of koalas provide an ideal case study to examine issues involved in identifying the role of endemic disease in conservation biology. Koala populations are in decline, amidst claims for many years that infectious diseases, particularly those with chlamydial etiology, play a key role in this loss. However, weak associations between prevalence of infection, clinical signs of disease, and population decline mean that it remains unclear whether infectious disease is a primary driver of koala population decline. There are multiple causes of koala decline including drought, habitat destruction, and disease. Welldesigned experiments, linked to appropriate models, are necessary to determine the true role of infectious disease in the current koala population declines and whether a focus on disease is likely to be a feasible, let alone the most cost-effective, means of preventing further declines.

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A 5-year Chlamydia vaccination programme could reverse disease-related koala population decline: Predictions from a mathematical model using field data

Cited by 16 publications

References 29 publications

Induction of partial immunity in both males and females is sufficient to protect females against sexual transmission of Chlamydia

Induction of partial immunity in both males and females is sufficient to protect females against sexual transmission of Chlamydia

Comparison of subcutaneous versus intranasal immunization of male koalas (Phascolarctos cinereus) for induction of mucosal and systemic immunity against Chlamydia pecorum

Assessing the significance of endemic disease in conservation—koalas, chlamydia, and koala retrovirus as a case study

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