Exploring the Potential Pathogenicity of Environmental Chlamydiae
Chlamydiae are pathogenic bacteria that cause many known human infections such as, trachoma, conjunctivitis, infant pneumonia, nongonococcal urethritis and female genitourinary disease. The discovery of new species of Chlamydiae in free-living amoebae has expanded diversity and has now opened the door for potential pathogenicity of those environmental Chlamydiae (1).
Chlamydiae are responsible for many human infections such as preventable blindness and sexually transmitted disease (2). These present –day pathogens only make up half the known Chlamydiae. The other half are environmental Chlamydiae ...view middle of the document...
Pathogenic Chlamydiae have lost more genes because they have a more stable niche where as environmental Chlamydiae (UWE25) are subjected to many different environments in their amoebae hosts (2). Although there is only a small amount of genes conserved between pathogenic Chlamydiae and UWE25, they both exploit their host’s ATP by using an ATP/ADP translocase to import ATP from the cytosol (2). They also share genes for a Type III secretion system which is a syringe like apparatus used to inject host cells with virulence proteins (5), which may indicate that environmental Chlamydiae have pathogenic potential as well.
(figure 2 phlyogeny of Type III secretion systems (2))
Another commonality between UWE25 and present-day pathogenic Chlamydiae is the presence of a protease-like activity factor (CPAF). It is secreted by the Type III secretion system into the host cytoplasm and is able to degrade human transcription factors needed for major histocompatibility complex. CPAF has been recognized as a virulence factor for today’s pathogenic Chlamydiae therefore it may be another indication that P. acanthamoebae is pathogenic also.
From an evolutionary stand point, the absence of substantial gene acquisition after the point of divergence between pathogenic and environmental Chlamydiae allows the inference that UWE25 is genetically similar to the last common ancestor (2).
Materials and Methods:
Testing for correlation between P. acanthamoebae and Human Respiratory Infections.
Clinical samples will be taken from humans with respiratory infections, as well as uninfected humans. PCR analysis of the 16S rRNA gene sequence will be performed to confirm Parachlamydia acanthamoebae infection. Once positive results of infections are determined MLST analysis will be done to confirm the strain of P. acanthamoebae present.
P. acanthamoebae will then be propagated on Vero cells using cell culture after being initially recovered by amoebal coculture (6). Once propagated, fluorescent in situ hybridization (FISH), will be performed using a “Chlamydiales” probe developed by Poppert et al (10).
To accompany the molecular and culture techniques a serology test will also be done. Immunofluorescence has been done in the past successfully with Parachlamydiaceae (7, 8) so it will be done here as well. To confirm any positive results of Immunofluorescence a Western blot will be carried out.
Upon completion of the molecular, culture and serological testing, the results will be compiled and statistically analyzed to determine if there is a mathematical correlation between human respiratory infections and the presence of P. acanthamoebae.
Discussion: Expectation of results, limitations, and applications
Expectations of results
The expectation of this experiment is to produce results that support a...