Vitrotest® Anti-HCV

• Solid phase: breakable microplate ELISA is coated with recombinant antigens (core, NS3, NS4 and NS5).
• Conjugate: monoclonal antibodies to human IgG and IgM conjugated to horseradish peroxidase.
• Chromogen: ready to use TMB solution.
• Volume of sample for analysis: 40 μl.
• Assay time: 2 hours.

According to the World Health Organization, approximately 150 million people are chronically infected with hepatitis C, and each year more than 350 thousand people die of hepatitis C-related liver disease. The disease may be either acute or chronic, and it often occurs without symptoms. However, chronic infection leads to liver cirrhosis and hepatocellular carcinoma development.

The causative agent of the disease is Hepatitis C Virus (HCV), a small enveloped single-stranded RNA virus (50 nm in diameter), belong to the Flaviviridae family. HCV genome has sequences encoding structural and nonstructural proteins. The structural antigens are nucleocapsid protein (core) and two envelope proteins (E1 and E2). Nonstructural proteins are complex proteins with enzymatic activity (NS2, NS3, NS4a, NS4b, NS5a and NS5b). In response to virus infection specific antibodies to all viral proteins are produced in human bodies.

Incubation period of hepatitis C is 14-180 (average 45) days. After this period, symptoms could arise. They include fever, fatigue, loss of appetite, nausea, vomiting, abdominal pain, joint pain, jaundice. Yet, most (70-80%) people infected with HCV are asymptomatic. Roughly 20% of infected patients clear the virus spontaneously; the rest develop chronic infection. HCV is a leading cause of chronic hepatitis, which progresses into cirrhosis in 5-20% of cases over a period of 20-30 years.

HCV is spread mainly through blood-to-blood contact. Therefore, in developed countries virus infects primarily persons who have injected illicit drugs and recipients of blood transfusions before introduction of regular blood screening for HCV. In developing countries many HCV infections occur in the health-care institutions as a result of unhygienic injections and various surgical manipulations such as tattooing or circumcision. Of other routes of transmission, the most important are sexual and vertical, from mother to fetus. Sexual transmission is regarded as a minor risk factor. Virus transmission from HCV-infected mother to unborn child is possible, with rates of transmission of around several percent.

HCV is divided into six major genotypes that can be further divided into several subtypes from A to L. The amino acid sequences of the major HCV genotypes differ approximately 30% from each other. The genotypes 1, 2 and 3 are found throughout the world whereas the distribution of the other genotypes is much more restricted. The immunity after cleared infection does not result in reliable protection against reinfections.

The overall worldwide prevalence of HCV is approximately 3%. The highest HCV prevalence figures (up to 10–20%) are found in Egypt. The prevalence of HCV infection varies remarkably and, for instance, in different European countries it ranges from 0,1% to 4%.

Adaptive immune responses are typically delayed during acute HCV infection. HCV RNA can be detected 1–3 weeks following infection, but neither HCV-specific T-cells nor HCV-specific antibodies are observed until 1–2 months after infection. The titre of IgG antibodies during the acute phase is relatively low in comparison with other virus infections in the majority of patients, gradually increasing during transformation to chronicity. In patients with resolved infection the titers of IgG after cure are low and often not detectable.

The IgM response in acute HCV infection also does not follow the classical pattern when IgM antibodies precede IgG response. Firstly, it was shown that HCV-specific IgM is more readily detected in chronically than in acutely infected patients (80% and 50% respectively); besides, the IgM titers under chronic infections are higher. Secondly, HCV-specific IgM and IgG are both almost simultaneously detected in acute infection. In individuals recovered from the infection no anti-HCV IgM antibodies are detectable.

A number of diagnostically relevant antigenic epitopes have been found within the C region, E2, NS3, NS4A/B and NS5 proteins, while E1, NS2 and NS5B are less immunogenic. In one study on chronic HCV patients, the following data on prevalence of antibodies were obtained: E2 – 98%, core-97%, NS3-88%, NS5A-68%, and NS4-48%. These data were similar to those observed by other investigators. Antibody titers were highest for core protein while titers for other proteins were considerably lower.

Antibody response against different HCV proteins is temporarily regulated. After infection, relatively early in the acute phase anticore antibodies are produced whereas significant levels of anti-E2 and anti-NS antibodies are detected only during the chronic phase. In recovering patients, anti-core antibodies persist longer than anti-NS antibodies, which often disappear.