Detection of giant viruses associated with free living amoeba from water sources in Iraq

Free-living amoebae (FLA) are gaining attention due to their associated with serious infections and their role as biological carriers for various bacteria and viruses. This study was conducted in Al-Nasiriyah City, southern of Iraq, to detect the prevalence of FLA and related giant viruses (Mimivirus and Marseillevirus) in different water sources using morphological and molecular approaches. A total of 87 water samples including tap water, mid river, Cliff riverbank (cliff of river), waterwheel, waste water and refrigerator and air conditioner water samples) were collected and cultured on non-nutrient agar seeded with Escherichia coli to isolate FLA. Polymerase chain reaction (PCR) and sequencing were performed to confirm the FLA identification FLA and detect associated mimivirus and marseillevirus. The results showed that 11.5% of samples were positive for FLA, while 3.4% were positive for each Mimivirus and Marseillevirus. Majority of FLA isolates (7 out of 10) isolated from cliff of river, which also contained all Mimivirus-positive samples in contrast, Marseillevirus was detected in mid-river and tap water, with statistically significant differences (p ≤ 0.05). A strong correlation was observed between Mimivirus and FLA occurrences (p = 0.002), whereas no significant association was found between Marseillevirus and amoebic isolation., This study revealed that diverse water sources in Iraq serve as potential reservoirs for potentially pathogenic FLA. Thus, this is the first report of Mimivirus and Marseillevirus in Iraqi’s aquatic environment, underscoring the need for further research on their prevalence and ecological roles. Regular monitoring of water sources is recommended to assess public health risks.