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Volume 6
Journal of Infectious Diseases and Therapy
ISSN: 2332-0877
Infection Congress 2018
March 01-02, 2018
Page 36
conference
series
.com
March 01-02, 2018 Berlin, Germany
5
th
International Congress on
INFECTIOUS DISEASES
Peter Timms, J Infect Dis Ther 2018, Volume 6
DOI: 10.4172/2332-0877-C1-037
Development of a chlamydial vaccine for koalas: Protection against infection as well as disease
W
ild koala populations continue to experience serious declines as a result of several threatening factors including: loss of
habitat; motor vehicle trauma; dog attacks and; chlamydial disease. Chlamydial infections are associated with diseases
ranging fromocular disease leading to blindness, as well as urinary and genital tract disease, leading to female infertility. Modeling
shows that targeting chlamydial disease would have a major impact on stabilizing population decline. Our previous studies have
demonstrated that koalas can be safely immunized with a vaccine containing a mixture of chlamydial major outer membrane
protein (MOMP) antigens combined with a single or three-dose subcutaneous regime. In our most recent, large scale, field trial of
the vaccine, we vaccinated 30 koalas that were outwardly clinically healthy but either chlamydia PCR negative or chlamydia PCR
positive, and followed them for 1-2 years to assess the protective effect of the vaccine (compared to a control group of unvaccinated
koalas). We observed strong, specific and long-lasting immune responses in the vaccinated koalas; high titer antibody responses
(as measured by ELISA and also in vitro neutralization) as well as chlamydia-specific cytokine responses (interferon-gamma
and IL-17 in particular). For animals which were chlamydia PCR positive at the time of vaccination, we observed a significant
reduction in their infection PCR load (at both the ocular and urogenital tract sites). We also observed protection from progression
to clinical disease in the vaccinated animals. We have also conducted a small trial to vaccinate animals which already have clinical
signs of ocular disease. Instead of the normal practice of administering antibiotics (chloramphenicol, daily for 28 days, which
severely disrupts the animal’s gut microbiome) we vaccinated four animals with a single dose, 3-MOMP vaccine. For all vaccinated
animals, their chlamydia PCR load decreased, often to zero, and in two animals at least, we observed a decrease in their clinical
disease score. These results are promising for the future development of an effective chlamydial vaccine for use in captive as well
as wild koalas.
Recent publications
1. Timms P (2017) Novel strategies for developing vaccines bring encouraging progress. Pathogens and Disease 29:75.
2. Desclozeaux M, Robbins A, Jelocnik M, Khan S, Hanger J, Gerdts V, Potter A, Polkinghorne A and Timms P (2017)
Immunization of a wild koala population with a recombinant Chlamydia pecorum Major Outer Membrane Protein
(MOMP) or Polymorphic Membrane Protein (PMP) based vaccine: New insights on immune response, protection and
clearance. PLoS One 12(6):e0178786.
3. Desclozeaux M, Jelocnik M, Timms P, Whitting K, Saifzadeh S, Bommana S, Potter A, Gerdts V and Polkinghorne A
(2017) Safety and immunogenicity of a prototype anti-chlamydia pecorum recombinant protein vaccine in lambs and
pregnant ewes. Vaccine 35: 3461–3465.
4. Marsh J, Ong V, Lott W, Tyndall J, Timms P and Huston W (2017) Chlamydia trachomatis HtrA: the lynch pin of the
chlamydial surface and a promising therapeutic agent. Future Microbiology 12:817–829.
5. Lau A, Kong F, Fairley C, Donovan B, Chen M, Bradshaw C, Boyd M, Amin J, Timms P, Tabrizi S, Regan D, McNulty A
and Hocking J (2017) Treatment efficacy of azithromycin 1g single dose versus doxycycline 100mg twice daily for 7 days
for the treatment of rectal chlamydia among men who have sex with men - a double blind randomised controlled trial
protocol. BMC Infectious Diseases 17:35.
Peter Timms
University of the Sunshine Coast, Australia