To protect itself, the Leishmania parasites have developed different mechanisms to protect itself against host defenses, such as:
Previous studies have shown the possibility that acquisition of drug resistance could affect the fitness of the parasites, influencing properties involved in parasite proliferation. Researchers then decided to evaluate whether L. donovani lines, which are experimentally resistant to single anti-leshmanial drugs or to a combination of drugs, could have an advantage over susceptible cells in tolerating stress conditions. Researchers placed resistant and susceptible cell lines under different stress conditions, and recorded the growth of the cell lines, using Luciferase as an indicator of parasite proliferation. The stress conditions the cell lines were placed under were:
resultsIn the absence of nutritional stress, neither the resistant nor the susceptible cell lines showed any significant advantage over the other. However, during the late stationary phase assay, it was observed that resistant cell lines had higher growth rates than the susceptible cells, probably due to a higher resistance to stress conditions that were present during the stationary stage. Similarly, under starvation conditions, resistant cell lines, more specifically those resistant to a combination of drugs, demonstrated an advantage over susceptible cell lines in the absence of nutrients. The higher survival rates of resistant cell lines were probably due to their ability to adapt their metabolism to handle the stress of starvation. Under heat shock and pH stress, resistant cell lines once again demonstrated higher tolerance against such conditions compared to susceptible cell lines. This suggests that resistant strains could demonstrate a higher survival rate inside hosts during their life cycle. conclusionLeishmania cell lines that were experimentally resistant to single or combination of anti-leishmanial drugs have exhibited an advantage over susceptible cell lines in terms of fitness, presumably due to a higher tolerance to stress conditions. Therefore, if such drug-resistant parasites were to be spread around in the environment, it could pose problems towards strategies to control the disease, such as chemotherapy.
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August 2015
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