Hepatitis C virus (HCV) infection is very common in Egypt and the middle east. The disease affects multiple body organs and may proceed to hepatocellular carcinoma. The viral disease causes changes in the microbial symbiosis in the human body. Thus, the analysis of the microbiome may provide a means of diagnosis for HCV infection.

Thus, this study will be held to detect if the microbiome of patients having HCV differ from that of normal individuals.

Human oral cavity is a great habitat for more than 600 species of bacteria, known as oral microbiota, living in equilibrium. Oral microbiota plays an important role in maintaining oral health; however when the balance in oral bacterial population is disturbed- known as dysbiosis- oral and systemic diseases may arise.

Some systemic diseases were proven to be associated with oral dysbiosis. Among these diseases are diabetes mellitus, cardiovascular diseases, breast cancer, pancreatic cancer, autoimmune liver diseases, hepatic encephalopathy and hepatitis B infection.

Hepatitis C virus (HCV) is considered an epidemic disease in Egypt; affecting about 10% of Egyptians ranging between 15 and 59 years of age. HCV infection damages the liver progressively causing liver cirrhosis, hepatic encephalopathy and may proceed to hepatocellular carcinoma.

Due to being a serious disease, together with the promising results of the newly discovered directly acting antiviral agents in treatment of chronic HCV, medicine has been concerned with finding efficient methods for its early diagnosis; in order to ensure early effective treatment and prevent serious complications.

Evidence suggests that a link exists between dysbiotic oral microenvironment and liver disease through oral-liver-gut axis. Attempts have been made to investigate the complex oral microbiota. With the advent of whole-genome sequencing technology, the genome of microbes have been possible to be sequenced in what is known as microbiome. Analyzing the genome of complex environment containing multiple individual microbes is called metagenomics.

Oral microbiome depends on sequencing of the 16S rRNA to provide a map of all oral microbiota available in the oral cavity. The technology of oral microbiome sequencing advanced from Sanger sequencing, that had shallow sequencing effort, to high throughput sequencing combined with bioinformatic tools, that allowed for comprehensive study of the complex microbiome.

Dysbiosis has been used for diagnosis of liver diseases through stool analysis. Only one study used oral dysbiosis to diagnose hepatic encephalopathy and another one used it in testing hepatitis B infection. However, oral dysbiosis has not been used to diagnose HCV infection before.

Understanding the oral microbiome at state of health and its change at state of disease can help predict the early stages of disease and treat it before further damage and disease progression occur. It can also help treat each patient according to the specific microbiome detected through personalized medicine. Furthermore, targeted treatment to each patient's specific microbiome can be introduced using specific prebiotics and probiotics to maintain the bacterial symbiosis and so assist the immune system in its continuous antiviral battle.

Inclusion Criteria:

• 1. Patients 18 years or older. 2. Non-smokers

Exclusion Criteria:

• 1. Patients who took any antibiotic or probiotics in the past month. 2. Patients having known active bacterial, fungal or other viral disease. 3. Patients having clinically apparent oral disease. 4. Patients undergoing radiotherapy

The participants will be divided into three groups:

Group I: Patients diagnosed with Hepatitis C virus. Group II: successfully treated chronic HCV patients Group III: Healthy individuals

They will be asked to rinse gently, then buccal mucosal swabbing takes place.