The use of dried blood spots for assessing antibody response to hepatitis A virus after natural infection and vaccination

Abstract

During recent years, vaccination against hepatitis A has been implemented in several countries. It is expected that the increase in mass vaccination against hepatitis A will eventually result in a decreased prevalence of anti-HAV antibodies in the general population. For this reason, a suitable clinical sample for diagnosis of hepatitis A must be sufficiently sensitive to enable detection of lower antibodies titers. In this study, the feasibility of using dried blood spots (DBS) was assessed for the detection of anti-HAV antibodies after a natural infection and vaccination. Seventy-four DBS and paired plasma samples were obtained from a group of college students for a cross-sectional hepatitis A seroepidemiological study. Forty-six students seronegative for anti-HAV were selected randomly and immunized with an inactivated hepatitis A vaccine using an 0-6 month schedule. Seroconversion was monitored in paired plasma and DBS samples 6 months after the first dose followed by a period of 8 and 24 months after the second dose. A strong correlation between OD/CO rates of paired plasma and DBS samples for the detection of anti-HAV was observed. The sensitivity and specificity of the DBS compared with plasma for the detection of anti-HAV antibodies after natural infection was 100%. The sensitivity of DBS in samples collected 24 months after the second dose of hepatitis A vaccine was 95.4%. The results showed that DBS samples can be used for the detection of anti-HAV antibodies both after natural infection or vaccination.

Declining prevalence of hepatitis A virus antibodies among children from low socioeconomic groups reinforces the need for the implementation of hepatitis A vaccination in Brazil

“…All blood samples were obtained by pricking the finger and depositing a blood spot on filter paper (DBS), a process that represents an easy and inexpensive method to collect, transport and store samples. This method has previously been observed to have a sensitivity and specificity of 100% when compared with collection of plasma for the detection of anti-HAV antibodies after infection (Melgaço et al 2011). Seroepidemiological surveys to detect the presence of antibodies are typically performed by collecting venous blood by venipuncture.…”

“…The sample was processed and assayed for total antibodies against HAV (anti-HAV) using a commercial enzyme immunoassay (Bioelisa HAV, Biokit, Spain) according to previously described protocols (Melgaço et al 2011). …”

A single dose of inactivated hepatitis A vaccine promotes HAV-specific memory cellular response similar to that induced by a natural infection

“…Twenty-two healthy individuals (21.0 ± 0.45 years) who were seronegative for anti-HAV were randomly selected and immunized with an inactivated hepatitis A vaccine (Merck Sharp & Dohme, West Point, PA, USA, lot 0526F) using a 0-6 month schedule, as previously described [5]. Of these individuals, 12 (54.5%) were female.…”

“…Immunization programs for children (≥1 year of age) have been introduced in several countries [4][5][6]. A two-dose vaccination schedule is generally used at an interval of 6-18 months between the first (primary) and second (booster) doses.…”

Hepatitis A seroprevalence in public school children in Campos dos Goytacazes, Rio de Janeiro State, Brazil, prior to the introduction of the hepatitis A universal childhood vaccination

“…A dried blood spot (DBS) sample was obtained from each subject enrolled in the study and further processed and assayed for total antibodies against HAV (anti-HAV) using a commercial enzyme immunoassay (Anti-HAV SYM, Symbiosis, Brazil) following the methodology previously described by Melgaço et al 26 .…”