Hepatit C virus
Europe has an overall HCV prevalence of about 1%. The prevalence of HCV in the big cities of former Soviet Union well exceeds 1% and is probably increasing (Onishchenko, 2001; Bobkova et al., 2002). A cross-sectional Russian study of over 2500 individuals in Siberia revealed the anti-HCV IgG prevalence of 5.6% (Shustov et al., 2005).
Hepatitis C virus is spread with infected blood and blood products. The most common routes are sexual, mother-to-child in delivery, by tattooing, piercing or other interfering cosmetic manipulations. One of the important modes of spread is intravenous drug abuse. The global epidemic of drug addictions has also reached the area of the former Soviet Union, creating an increasing burden to health care systems. Among intravenous drug abusers in the big Russian cities, the HCV prevalence has reached 70% (Rhodes T et al., 2006). Another route dragging much attention is nosocomial. Much of the infection was spread earlier through blood transfusion and use of uncontrolled blood products. For Baltic countries, in the early 1990-ies up to 70% of repeat plasma donors in Lithuania had become HCV infected (Ambroziatis A et al, PhD thesis). Later, the prevalent nosocomial routes were practicing unsafe procedures or not strictly following safety rules and precautions. This can go through poor control of poorly decontaminated injection gear as well as the use of exposure-prone procedures and inappropriate infection control measures on the ward (see, for example, publications of the Malmö and Riga partners of the Network: Almroth G et al, 2002; Dumpis U et al., 2003). Obviously frequent but underscored and difficult to prove and follow is HCV infection from medical personal unaware of their hepatitis C infection (see publication from the Malmö partner of the Network; Cardell K et al, 2008).
Many HCV patients face life-threatening symptoms
Following acute HCV infection, 50-80% of HCV patients become chronic carriers; and 20 to 30% chronic hepatitis C carrier will eventually face life-threatening symptoms: chronic active hepatitis, liver cirrhosis, hepatocellular carcinoma, and extrahepatic disorders. The desirable event, long time spontaneous clearance of HCV occurs only in 20-50%. Interestingly, many acutely infected HCV patients show a strong tendency to temporarily control virus infection for a few months around the time of seroconversion to hepatitis C antibodies (anti-HCV) but virus levels later rebound. In addition, there is a serious case finding problem for acute hepatitis C, since symptoms during the acute phase in almost all cases are mild and rarely brought to medical attention and remains unrecognized unless prospectively identified (see below). In acute hepatitis C 90% never develop jaundice, for many physicians a hallmark of acute hepatitis. Also, since the majority acquires HCV through illicit activities such as injecting drugs, only a minority of acute HCV infections is recorded by the health care system. Consequently, we still lack full understanding of the early and probably crucial events of acute HCV infection. More studies involving larger patient cohorts have to be conveyed to gain knowledge of the immune host-related correlates of HCV clearance.
The reasons HCV clearance or chronization include also virus variability that ensures an effective escape from the immune response, and the capacity to adapt to the new host/new replication conditions. Altogether, they stand for what is known as viral replication fitness (Domingo E et al, 2005). Viral adaptation generates polymorphisms that play a distinct role in the clinical course and outcome hepatitis C infection, including response to antiviral treatment.
Intensive HCV vaccine research
No HCV vaccine is yet in-sight due both to virus variability and its capacity to suppress host immune defense. The growing need to diminish the magnitude of HCV associated liver disease drives intensive HCV vaccine research. Series of HCV vaccine candidates have been moved into clinical trials (Wintermeyer P & Wands JR, 2007). One such is the peptide vaccine IC41 consisting of a panel of MHC class I and class II restricted epitopes adjuvanted by poly-L-arginine administered to healthy volunteers (Firbas C et al, 2007) and to chronic HCV patients including non-responders to the standard therapy (Klade CS et al, 2008; Schlaphoff V et al, 2007). Another therapeutic vaccine employed peptides chosen individually by the ability to induce the strongest in vitro cellular response (Yutani S et al, 2007). In yet another vaccine trial, chronic hepatitis C patients received the recombinant HCV envelope protein E1 (Nevens F et al, 2003).
The first clinical trial is currently ongoing of HCV DNA vaccine consisting of a codon-optimized NS3/4A gene administered to chronic hepatitis C patients (CHRONVAC-C®;
Phase I/IIa Dose Ranging CHRONVAC-C® Study in Chronic HCV Patients
Limited success of the current trials indicates the need for continued search of the vaccine candidates and vaccination approaches that would result into more effective preventive and therapeutic vaccination options.
Although May is Hepatitis Awareness Month, viral hepatitis needs more attention throughout the year. One of the main findings from last year’s 
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