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The risk of sexual transmission of hepatitis C virus (HCV) infection was evaluated among 895 monogamous heterosexual partners of HCV chronically infected individuals in a long-term prospective study, which provided a follow-up period of 8,060 person-years. Seven hundred and seventy-six (86.7%) spouses were followed for 10 yr, corresponding to 7,760 person-years of observation. One hundred and nineteen (13.3%) spouses (69 whose infected partners cleared the virus following treatment and 50 who ended their relationship or were lost at follow-up) contributed an additional 300 person-years. All couples denied practicing anal intercourse or sex during menstruation, as well as condom use. The average weekly rate of sexual intercourse was 1.8. Three HCV infections were observed during follow-up corresponding to an incidence rate of 0.37 per 1,000 person-years. However, the infecting HCV genotype in one spouse (2a) was different from that of the partner (1b), clearly excluding sexual transmission. The remaining two couples had concordant genotypes, but sequence analysis of the NS5b region of the HCV genome, coupled with phylogenetic analysis showed that the corresponding partners carried different viral isolates, again excluding the possibility of intraspousal transmission of HCV. Our data indicate that the risk of sexual transmission of HCV within heterosexual monogamous couples is extremely low or even null. No general recommendations for condom use seem required for individuals in monogamous partnerships with HCV-infected partners.

Long-term follow up studies of hepatitis C virus (HCV) infection

Hepatitis E infection is typically associated with areas in which hepatitis E virus (HEV) is endemic. Except for a few cases in Europe and in the United States, acute hepatitis E is usually associated with travel to endemic areas. We set out to determine the etiologic role of HEV in acute non-A-C hepatitis in Italy. The presence of HEV-RNA and antibody was determined in 218 patients diagnosed with acute viral non-A-C hepatitis. Acute hepatitis E infection was defined by the presence of HEV-RNA in sera and positivity for IgM anti-HEV and seroconversion to IgG anti-HEV. Acute hepatitis E was found in 10.1% of the patients with acute non-A-C, with 95.5% exhibiting a benign course. A more severe course was observed in a patient co-infected with HAV and HEV. Most cases were travelers to endemic areas, although 18.2% reported no travel. One patient was from a household with an infected patient. Sequence analyses of the polymerase chain reaction (PCR) product derived from a patient who never visited endemic areas, identified an isolate that is divergent significantly from all reported isolates of HEV (79.5-85.8% nucleotide identity). Evidence from this study suggests that HEV accounts for approximately 10% of acute non-A-C viral hepatitis in Italy, diagnosed generally in travelers returning from endemic areas. However, the identification of a new HEV variant in an individual who never indicated travel or contact with individuals associated with endemic areas, suggests that this virus may be native to Italy.

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Hepatitis B virus is a worldwide leading cause of acute and chronic liver disease including cirrhosis and hepatocellular carcinoma. Effective vaccines have been available since the early '80s and vaccination has proved highly successful in reducing the disease burden, the development of the carrier state and the HB-related morbidity and mortality in the countries where vaccination has been implemented.   Neutralizing (protective) antibodies (anti-HBs) induced by vaccination are targeted largely towards the amino acid hydrophilic region, referred to as the common a determinant which is present on the outer protein coat or surface antigen (HBsAg), spanning amino acids 124-149. This provides protection against all HBV genotypes (from A to H) and is responsible for the broad immunity afforded by hepatitis B vaccination. Thus, alterations of residues within this region of the surface antigen may determine conformational changes that can allow replication of the mutated HBV in vaccinated people. An important mutation in the surface antigen region was identified in Italy some 25 years ago in infants born to HBsAg carrier mothers who developed breakthrough infections despite having received HBIG and vaccine at birth. This virus had a point mutation from guanosine to adenosine at nucleotide position 587, resulting in aa substitution from glycine (G) to arginine (R) at position 145 in the a determinant. Since the G145R substitution alters the projecting loop (aa 139-147) of the a determinant, the neutralizing antibodies induced by vaccination are no longer able to recognize the mutated epitope. Beside G145R, other S-gene mutations potentially able to evade neutralizing anti-HBs and infect vaccinated people have been described worldwide. In addition, the emergence of Pol mutants associated with resistance to treatment with nucleos(t)ide analogues can select viruses with crucial changes in the overlapping S-gene, potentially able to alter the S protein immunoreactivity. Thus such mutants have the potential to infect both naïve and immunized people, negatively affecting the efficacy of both the antiviral treatment and the vaccination programs. Despite concern, at present the overall impact of vaccine escapes mutants seems to be low and they do not pose a public health threat or a need to modify the established hepatitis B vaccination programs. The development of novel NAs with a high barrier to resistance is warranted.

Activated lymphocytes release nano-sized vesicles (exosomes) containing microRNAs that can be monitored in the bloodstream. We asked whether elicitation of immune responses is followed by release of lymphocyte-specific microRNAs. We found that, upon activation in vitro, human and mouse lymphocytes down-modulate intracellular miR-150 and accumulate it in exosomes. In vivo, miR-150 levels increased significantly in serum of humans immunized with flu vaccines and in mice immunized with ovalbumin, and this increase correlated with elevation of antibody titers. Immunization of immune-deficient mice, lacking MHCII, resulted neither in antibody production nor in elevation of circulating miR-150. This study provides proof of concept that serum microRNAs can be detected, with minimally invasive procedure, as biomarkers of vaccination and more in general of adaptive immune responses. Furthermore, the prompt reduction of intracellular level of miR-150, a key regulator of mRNAs critical for lymphocyte differentiation and functions, linked to its release in the external milieu suggests that the selective extracellular disposal of microRNAs can be a rapid way to regulate gene expression during lymphocyte activation.