Electronic Nose Versus Quadrupole Mass Spectrometry for Identifying Viral Hepatitis C Patients

Ehab I. Mohamed; Sameh M. El-Ghnam; Amani M. Bayoumi; Samir M. Abdel-Mageed; Doaa A. Ghareeb; Brian Ross

Disclosures

J Viral Hepat. 2022;29(2):147-155. 

In This Article

Abstract and Introduction

Abstract

Hepatitis C is a leading cause of liver disease and transplantation and is a significant burden on public health worldwide. This study aimed to apply the Electronic Nose (E-Nose) and quadrupole Mass Spectrometry (MS/MS) technologies for screening blood samples from hepatitis C patients and healthy controls. We analysed volatile organic compounds (VOCs) in the headspace over blood samples to identify those VOCs characteristic for diagnosing hepatitis C patients. The study comprised 150 acute hepatitis C patients with age range: 24–59 years, and mean age ±SD: 41.5 ± 12.8 years and 150 age-matched healthy controls (age range: 24–51 and mean age: 40.11 ± 4.89 years) from the Hospital of the Medical Research Institute, Alexandria University, Alexandria, Egypt. Collected blood samples were analysed qualitatively and quantitatively using the E-Nose and MS/MS techniques, respectively. Principal component analysis of the E-Nose 10-sensor responses accurately classified blood samples from hepatitis C patients and healthy controls. The first two principal components explained over 98.35% of the variance in signals with no false-positive (healthy controls) or false-negative (hepatitis C patients) results. MS/MS showed two fragmentation ions at m/z of 104 and 151 Da with the positive electrospray ionization mode (ESI+) in blood samples for hepatitis C patients, but not for healthy controls or background water samples. We identified the two specific fragmentation ions at m/z 104 and m/z 151 Da as malonic acid (MF: C3H4O4; MW: 104.06 g/mol) and monosaccharide pentose (MF: C5H10O5; MW: 150.13 g/mol) in VOCs of the headspace over blood samples for hepatitis C patients. This provides a rationale for developing diagnostic tests for hepatitis C virus based on altered trace VOCs concentrations using the relatively inexpensive, easy-to-use, portable and non-invasive E-Nose technology.

Introduction

Hepatitis C is a liver disease caused by the blood-borne hepatitis C virus (HCV). HCV is a hepatotropic RNA virus of the genus Hepacivirus in the Flaviviridae family, which can inflict acute and chronic hepatitis.[1] Among various genotypes of HCV, genotype 1 is the most prevalent, accounting for 46% of all HCV infections, followed by genotype 3, which is 22% prevalent. Genotypes 2 and 4 each have a 13% prevalence.[2,3] Of the six major HCV genotypes, genotype 4 represents more than 85% of all hepatitis C cases among Egyptians.[1,3,4] Egypt has the highest prevalence of hepatitis C globally, with approximately 22% of Egyptian blood donors testing positive.[5] It is estimated that roughly 15 million Egyptians currently suffer from hepatitis C, with 170,000 to 200,000 new cases every year.[1,2,5] Moreover, they suffer from exceptionally high morbidity and mortality rates compared to other countries of the Eastern Mediterranean and the European Regions, with more than 40,000 dying from the disease each year.[6] Estimates of chronic hepatitis C infection amount to about 71 million people worldwide, with nearly 399,000 deaths mostly from cirrhosis and hepatocellular carcinoma each year.[3,5]

HCV is transmitted by parenteral or permuscosal exposure to infected blood or body fluids in many ways, such as intravenous drug users who use contaminated needles; healthcare workers accidentally punched with a needle from an infected person; patients undergoing hemodialysis; sexually active persons who engaged in sexual contact with multiple partners without proper protection; and patients who get an infected blood transfusion or organ transplant.[7,8] Hepatitis C is mainly asymptomatic with minor visible symptoms in its acute infection stage, which lasts for about six months. However, patients harbouring the disease for 20–40 years will develop chronic hepatitis C infection with noticeable symptoms (eg, fatigue, muscle aches and loss of appetite), resulting in fibrosis, cirrhosis and, ultimately, hepatocellular carcinoma.[1,5,8] Following the development of cirrhosis, the patient, will also likely experience weight loss, blood clotting problems, fluid retention in the abdomen, and jaundice, leading to significant impairment of their quality of life, ultimately, death.[1,9]

It is standard of care for detecting HCV infection by testing for anti-HCV antibodies with a serological test followed by a nucleic acid test, which measures HCV viral load and determines HCV genotype for patients with positive HCV antibodies before commencing and during treatment.[7] Besides, assessment of the degree of liver damage (ie, fibrosis and cirrhosis) can be carried out by liver biopsy or through a variety of non-invasive tests to guide treatment decisions and manage the disease. Hepatitis C can be treated with liver transplantation and antiviral medications, which necessitate the detection of the Q80K polymorphism upon treatment with simeprevir, the latter being most effective when used before the liver suffering substantial damage.[7,9] Moreover, quickly detecting HCV infection in blood samples could reduce transmission of the virus during blood transfusions.[7] As such, the ability to screen for those infected rapidly and easily with HCV can reduce the morbidity and mortality of the illness via multiple routes.

Volatile organic compounds (VOCs) in clinical matrices have increased interest in their diagnostic potential for many disorders due to their ability to act as non-invasive disease markers.[10] VOCs represent a wide range of stable chemicals at ambient temperature present in the exhaled breath, urine, blood, faeces and sweat, making them ideal candidates as diagnostic markers.[11] This form of metabolomics has been aided by emerging advances in Mass Spectrometry (MS/MS) instruments for quantifying these components using triple quadrupole linear ion trap systems due to their well-known selectivity and sensitivity. Nevertheless, this procedure demands highly skilled technicians and much elaboration time.[12]

Moreover, the recent availability of highly sensitive and portable technologies like Electronic Nose (E-Nose) has provided necessary tools for detecting disease-specific VOCs in clinical matrices quickly and cheaply.[13–15] An E-Nose is an artificial gas-sensing system consisting of an array of non-specific chemical sensors of variable numbers, usually between 10 and 32, capable of detecting and classifying VOCs using pattern recognition algorithms.[14] However, E-Noses can only qualitatively detect complex odour mixtures of VOCs associated with various diseases without identifying individual chemical species.[13–15] That is why we usually rely on MS/MS instruments to quantitatively detect specific compounds associated with a particular disease.[10]

The objective of this study was to determine if HCV infection can be associated with VOCs in the headspace over blood samples from pathologically confirmed hepatitis C patients and healthy control participants using E-Nose in comparison with quadrupole MS/MS.

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