Detection of immunoglobulin M antibody to hepatitis A virus in patients without acute hepatitis A: the usefulness of specific immunoglobulin G avidity

Development and Evaluation of a Molecular Hepatitis A Virus Assay for Serum and Stool Specimens

Hepatitis A virus (HAV) is an emerging public health concern and there is an urgent need for ways to rapidly identify cases so that outbreaks can be managed effectively. Conventional testing for HAV relies on anti-HAV IgM seropositivity. However, studies estimate that 10–30% of patients may not be diagnosed by serology. Molecular assays that can directly detect viral nucleic acids have the potential to improve diagnosis, which is key to prevent the spread of infections. In this study, we developed a real-time PCR (RT-PCR) assay to detect HAV RNA for the identification of acute HAV infection. Primers were designed to target the conserved 5′-untranslated region (5′-UTR) of HAV, and the assay was optimized on both the Qiagen Rotor-Gene and the BD MAX. We successfully detected HAV from patient serum and stool samples with moderate differences in sensitivity and specificity depending on the platform used. Our results highlight the clinical utility of using a molecular assay to detect HAV from various specimen types that can be implemented in hospitals to assist with diagnostics, treatment and prevention.

The serological markers of acute infection with hepatitis A, B, C, D, E and G viruses revisited

Viral hepatitis is a liver infection caused by one of the six hepatitis viruses: hepatitis A, B, C, D, E, and G virus (HAV to HEV and HGV). These agents differ in their biological, immunological, pathological and epidemiological characteristics. They cause infections that, when symptomatic, lead to clinical manifestations and laboratory findings that are not specific to a particular virus, often making differential diagnosis difficult, especially when no knowledge is available regarding the patient's medical history or the epidemiological background. A number of acute-phase serological markers, such as anti-HAV, anti-HBc, anti-HDV and anti-HEV IgM antibodies, are able to provide a clear indication of an infection caused by HAV, HBV, HDV or HEV. Anti-HCV antibodies and HGV/RNA are used for the diagnosis of HCV and HGV infections. The importance of each of these markers will be reviewed, and different factors that can interfere with the diagnosis of acute infections caused by these viruses will be described.

Multicentric evaluation of new commercial enzyme immunoassays for the detection of immunoglobulin M and total antibodies against hepatitis A virus

A multicentric clinical study was conducted on representative sera from 1,738 European and U.S. subjects for the evaluation of new anti-hepatitis A virus enzyme immunoassays from Bio-Rad Laboratories. Comparison with reference DiaSorin S.p.A. tests confirmed the good performance of Bio-Rad assays (99.85% and 99.47% overall agreement in detecting total antibodies and IgM, respectively).

The infective causes of hepatitis and jaundice amongst hospitalised patients in Vientiane, Laos

There is little information on the diverse infectious causes of jaundice and hepatitis in the Asiatic tropics. Serology (hepatitis A, B, C and E, leptospirosis, dengue, rickettsia), antigen tests (dengue), PCR assays (hepatitis A, C and E) and blood cultures (septicaemia) were performed on samples from 392 patients admitted with jaundice or raised transaminases (≥ × 3) to Mahosot Hospital, Vientiane, Laos over 3 years. Conservative definitions suggested diagnoses of dengue (8.4%), rickettsioses (7.3%), leptospirosis (6.8%), hepatitis B (4.9%), hepatitis C (4.9%), community-acquired septicaemia (3.3%) and hepatitis E (1.6%). Although anti-hepatitis A virus (HAV) IgM antibody results suggested that 35.8% of patients had acute HAV infections, anti-HAV IgG antibody avidity and HAV PCR suggested that 82% had polyclonal activation and not acute HAV infections. Scrub typhus, murine typhus or leptospirosis were present in 12.8% of patients and were associated with meningism and relatively low AST and ALT elevation. These patients would be expected to respond to empirical doxycycline therapy which, in the absence of virological diagnosis and treatment, may be an appropriate cost-effective intervention in Lao patients with jaundice/hepatitis.

Hepatitis A virus: serology and molecular diagnostics

The diagnosis of hepatitis A virus (HAV) infection is based on the detection of anti-HAV IgM. Shortcomings of this serological approach include the persistence of IgM after normalization of liver enzymes or its detection during polyclonal activation of the immune system due to unrelated viral infection or autoimmune diseases. Molecular diagnosis of HAV along with anti-HAV IgG avidity measurement are helpful in case of positive IgM where laboratory evidence of acute hepatitis is absent and there is no epidemiologic link to other cases. Molecular epidemiology allows us to determine whether viruses from different locations are related to each other and provides further understanding of viral epidemiology by identifying sources and transmission modes. It has been demonstrated that the rapid turnover of HAV strains in low-endemicity countries is caused by their introduction by travelers. Growing sequence databases allow for the identification of geographic origin of viral strains. Collaboration between surveillance laboratories, including database sharing, should be promoted for deeper investigation of outbreaks and improved prevention approaches.