ABSTRACT
Occult hepatitis B (HBV) infection (OBI), characterized by low viral loads, accounts for much of the risk of HBV transfusion-transmitted infection. With anticore antibodies (anti-HBc) screening introduced in England, the imperative to identify OBI donors has increased. We aimed to develop an ultra-sensitive PCR system and investigate risk factors for HBV DNA presence in blood donations. Seven extraction methods and three PCR assays were compared. The optimal system was sought to determine HBV DNA presence in anti-HBc-positive donations. Predictors of DNA positivity were subsequently investigated. Extraction from 5 mL of plasma increased sample representation and resulted in HBV DNA detection in low viral load samples (~0.5 IU/mL). Screening of 487 763 donations in 2022 identified two OBI donors and 2042 anti-HBc-positive donors, 412 of the latter with anti-HBs < 100 mIU/mL. Testing of 134 anti-HBc-positive donations utilizing the 5 mL extraction method identified two further HBV DNA-positive donations. Higher anti-HBc titer and anti-HBs negativity were significant predictors of DNA detectability in anti-HBc-positive donations. An ultrasensitive PCR assay identified potentially infectious donations increasing HBV DNA detection in anti-HBc-positive donors from 0.5% to 1.9%. Anti-HBc titers may further complement the risk stratification for DNA positivity in anti-HBc screening and minimize unnecessary donor deferral.
Subject(s)
Hepatitis B, Chronic , Hepatitis B , Humans , Hepatitis B virus/genetics , DNA, Viral , Blood Donors , Hepatitis B Core Antigens , Hepatitis B Antibodies , Hepatitis B Surface Antigens , Polymerase Chain Reaction/methods , Risk AssessmentABSTRACT
Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been shown to be detectable in blood from infected individuals. Though RNAemia frequencies are typically low, the presence of potentially infectious virus potentially poses a transmission risk during blood transfusion. Methods: Archived plasma samples were collected from blood donors who later reported possible SARS-CoV-2 infection with the wild-type strain, Delta variant, or Omicron variant. This was based on either symptom onset or a positive test within 2 weeks from their donation. Donations were tested for SARS-CoV-2 RNA, and information on symptoms and testing results were gathered during postdonation interview. Results: Of 518 archived plasma samples tested, 19 (3.7%) were found to have detectable levels of SARS-CoV-2 RNA. SARS-CoV-2 RNA was detected in donors who donated during the Delta (10/141 [7.1%]) and Omicron (9/162 [5.6%]) waves. SARS-CoV-2 RNA was not detected in donors who donated during the wild-type wave (0/215). Seventeen of 19 RNAemic donors reported symptom onset or a positive test within 2 days of donating. SARS-CoV-2 RNA was detected in asymptomatic or presymptomatic blood donors. Conclusions: Despite RNAemia being correlated with SARS-CoV-2 disease severity, RNAemia was detected in asymptomatic or presymptomatic blood donors.
ABSTRACT
A multiplex PCR using targets within the serotype-specific region of the capsular polysaccharide synthesis gene cluster of serotypes K1, K2 and K5 was evaluated using the 77 reference serotype strains of Klebsiella, and a panel of clinical isolates subjected previously to conventional serotyping. The PCR was highly specific for these serotypes, which are those most associated with virulence in humans and horses. PCR confirmed that isolates of the K5 serotype had cross-reacted with antiserum for other serotypes, particularly for K7. K5 isolates received by our laboratory were almost exclusively from thoroughbred horses, and were submitted for screening prior to breeding programmes. Most, including a reference strain isolated in 1955, belonged to a cluster of genetically similar isolates of sequence type (ST) 60. K1 isolates, all from humans, belonged to a previously identified cluster of ST 23.