Risk Minimization Measures for Blood Screening HIV-1 Nucleic Acid Amplification Technique Assays in Germany

Abstract

Background: Several publications describe HIV-1 RNA false-negative results or viral load underquantitation associated with Communauté Européenne(CE)-marked qualitative or quantitative nucleic acid amplification technique (NAT) assays. 6 cases occurred during blood screening in Germany, with 2 of them causing HIV-1 transmissions to recipients of blood components. The implicated NAT assays were mono-target assays amplifying in different viral genome regions (gag or long terminal repeat). Methods: Specimens characterized by HIV-1 NAT underquantitation or false-negative NAT results were comparatively investigated in CE-marked HIV-1 NAT systems of different design to identify potential reasons. The target regions of the viral nucleic acids were sequenced and these sequences compared to primers and probes of the assays. Potential risk minimization measures were considered for quantitative and blood-screening HIV-1 NAT systems. Results: Nucleotide sequencing of the viral target region in cases of HIV-1 RNA underquantitation or false-negative test results revealed new HIV-1 variants that were mismatched with primers and probes used in some mono-target assays. So far, dualtarget NAT assays have not been associated with mismatch-based false-negative test results. From 2015, the Paul Ehrlich Institute will request HIV-1 NAT assays of dual-target design or an analogous solution for further reducing the risk in blood screening. Conclusion: HIV differs from other blood-borne viruses with regard to its fast evolution of new viral variants. The evolution of new sequences is hardly predictable; therefore, NAT assays with only 1 target region appear to be more vulnerable to sequence variations than dual-target assays. The associated risk may be higher for HIV-1 NAT assays used for blood screening compared to quantitative assays used for monitoring HIV-1-infected patients. In HIV-1 screening NAT assays of dual-target design may adequately address the risk imposed by new HIV-1 variants.

Human Immunodeficiency Virus (HIV)

“…gag or LTR or integrase (IN), just HIV-1 of group M or also viruses from HIV-1 groups M, N, O and P can be detected [23,127,128,129,130]. Taking into account the genetic variability of the HIV genome, it is advantageous and therefore has become compulsory for Germany in 2015 to use so-called dual-target amplification techniques, i.e., assays that amplify two (or more) different regions of the HIV genome [131,132,133]. …”

Humanes Immunschwächevirus (HIV)

“…Referenzmaterial zum Nachweis verschiedener HIV-1-Genotypen ist erhältlich [126]. Der Einsatz der NAT ist trotz des hohen Arbeits-und Kostenaufwandes indiziert, denn die Mehrzahl der durch zelluläre Blutkomponenten möglichen HIVÜbertragungen der letzten Jahre (nach Ausschluss der Spenden von HIV-Antikörper-positiven Spendern) ist über die NAT verhindert worden [131][132][133][145][146][147][148].…”

“…Nachdem in mehreren Fällen NATTeste mit nur einer Primerbindungsregion-Erkennung HIV mit Mutationen in dieser Region nicht erkannt haben, wurde zur Erhöhung der Sicherheit die Erkennung von mindestens zwei Zielregionen (dual target-NAT) für das Spenderscreening verbindlich angeordnet [132,133].…”

“…Basierend auf den Daten zur Spendertestung und zur Hämovigilanz im Zeitraum 2007-2010 wird ein Übertra-gungsrisiko von 1 zu 9,64 Millionen Spenden angegeben [132]. Nimmt man neuere Restrisikomodelle, die konkrete Spenderintervalle in die Schätzung einbeziehen, liegt das geschätzte Restrisiko einer unerkannt infektiösen Vollblutspende etwas höher bei 1 zu 2,4 Millionen [159].…”

Knowledge Is Safety: The Time Is Ripe for Hepatitis E Virus Blood Donor Screening

“…In our opinion, the relative risk of transmission of HEV is exceedingly higher than for CMV/PVB19, Vollmer enormous efforts regarding HIV-NAT testing are carried out (e.g. dual-target-NAT [14]) to further minimize the already low residual infection risk. Very sensitive antigen-antibody assays are available, and the diagnostic window is shortened by NAT testing to only 2 days [15].…”