الفهرس 
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Abstract
The main objectives of the current study were to investigate the prevalence of the human polyomaviruses (HPyVs), JCV and BKV, in Egyptian wastewater and water; to evaluate the efficiency of the treatment plants in removal of these viruses from treated water and to study the role of JCV and BKV in colorectal cancer (CRC) in Egyptian CRC patients. Accordingly, the results of this study can be summarized in the following points:
1. The potentially oncogenic HPyVs, JCV and BKV, are highly disseminated in water environments worldwide. Both viruses show high prevalence in water and wastewater in different geographical areas.
2. There is no conclusive data on the efficiency of treatment plants in elimination of the viruses from water and wastewater, but it is clear from several studies that the treatment processes applied in most treatment plants cannot completely remove the viruses from wastewater before discharging it into rivers, leading to contamination of the water environments by the fecal viruses and facilitating the fecal-oral transmission of many infectious viruses.3. Since no data about HPyVs prevalence in Egyptian water environments was available at the beginning of this study and currently, few data about their prevalence is available, a total of 96 water and wastewater samples were included in this study for investigation of the prevalence of JCV and BKV in Egyptian water environments. The samples were collected as follow:
a. A total of 26 wastewater samples were collected from Zenin wastewater treatment plant (WWTP) as following: 13 raw sewages and 13 treated effluents.
b. A total of 46 wastewater samples were collected from Al gabal al asfar WWTP as following: 23 raw sewages and 23 treated effluents.
c. A total of 24 water samples were collected from El-Giza water treatment plant as following: 12 inlet Nile water samples and 12 outlet drinking water samples.
4. JCV shows high prevalence in raw sewages from both WWTPs as it has been detected in 69.2% (9/13) and in 65.2% (15/23) of raw sewage samples from Zenin WWTP and Al gabal al asfar WWTP respectively, while it was prevalent in 50% (6/12) of inlet Nile water samples.5. BKV shows higher prevalence than JCV in raw sewages from Zenin WWTP as it has been detected in 84.6% (11/13) of samples, while it shows lower prevalence than JCV in raw sewages from Al gabal al asfar WWTP as it has been detected in 56.5% (13/23) of samples. BKV, as JCV, was prevalent in 50% (6/12) of inlet Nile water samples.
6. The three treatment plants are varying in their efficiency of removal of both viruses. However, Zenin WWTP shows the highest removal efficiency as JCV and BKV have been removed from 77.7% (7/9) and 91% (10/11) of positive samples respectively. Al gabal al asfar WWTP shows low efficiency of JCV and BKV removal as JCV was eliminated from 26.6% (4/15) of positive samples, while BKV was eliminated from 15.4% (2/13) of positive samples. El-Giza water treatment plant showed moderate efficiency of JCV and BKV removal as JCV and BKV have been eliminated from 50% (3/6) of positive samples.
7. As HPyVs are considered potentially oncogenic viruses, there is a rising interest in the study of their role in the etiology of many cancers. JCV and BKV are considered a group 2B carcinogens (possibly carcinogenic to human) and mainly linked to colorectal cancer (CRC).8. In Egypt, CRC is with high prevalence in young people, has no hereditary basis, is not linked to bilharzias and usually present in advanced stage. However, there is no data about the possible role of the oncogenic viruses, especially JCV and BKV in its etiology and development.
9. A total of 50 biopsies from Egyptian patients were collected from general surgery department, faculty of Medicine, Ain Shams University. The study has been approved by the research ethics committee. 48 biopsies were collected from CRC patients, 24 from tumor tissues and 24 from tumor-adjacent normal mucosa from the same patients. 2 biopsies of normal mucosa were collected from non-CRC patients, underwent colonoscopy for other gastrointestinal disorders.
10. Age of CRC patients ranged from 30-82 years old, patients >50 years old represented 81.8% (18/22) of cases while
patients <50 years old represented 18.2% (4/22) of cases. Male patients represented 58.3% (14/24) of cases while female patients represented 41.6% (10/24) of cases. Two non-CRC patients included in this study, were males with 20 and 41 years old.
11. All tumor tissues, tumor-adjacent normal mucosa from CRC patients and normal mucosa from non-CRC patients were free from DNA of both viruses, JCV and BKV, indicating no prevalence of both viruses in Egyptian CRC patients, and thus no preliminary evidence on their role in the tumor etiology and development for further study.