,Koala numbers in South-East Queensland (SEQ) have declined dramatically over the last 20 years. Over this time, an increase in infectious diseases, including Chlamydia, has been observed. Chlamydia pecorum infection of the ocular and genital tracts is estimated to effect approximately 70% of koalas in SEQ. In females, genital infection of koalas has shown to induce severe reproductive tract pathology resulting in infertility that contributes to the observed decline in numbers. To date, minimal studies have investigated the effects of C. pecorum infection on male fertility including sperm quality and reproductive tract bacterial loads that leads to seminal transmission to females. This study was undertaken to investigate whether naturally occurring Chlamydia-infection identified in koala semen are viable to inoculate a cell line and act as a source of bacterial transmission.
In collaboration with Moggill Koala Hospital, semen was collected via electroejaculation from 120 wild koalas admitted to the hospital. Semen collected were assessed for motility and rate, % live/dead, concentration, morphology, % DNA fragmentation and Chlamydial speciation and quantitation determined through qPCR of seminal fluid. Chlamydia positive koala semen with PCR quantitated infectious load, was inoculated into a clean McCoy cell line and incubated. Fluorescently conjugated chlamydia MOMP antibody was used for the detection of chlamydial inclusion bodies within cell cytoplasm.
Results show inoculation of a clean cell line using naturally-infected koala semen. Observation of small chlamydial inclusion bodies and remnants of sperm flagella within the culture medium indicates presence of infection.
With the absence of experimental animals available to perform koala chlamydia inoculation studies, we have developed a secondary method that can assist in determining the infectious load of chlamydia within a koala semen sample. Results confirm that infectious chlamydial elementary bodies can be shed into koala semen and serve as a source of bacterial transmission to the female.