Sensitivity of individual and mini-pool nucleic acid testing assessed by dilution of hepatitis B nucleic acid testing yield samples

Abstract

Introduction:For nucleic acid testing (NAT) of blood donations, either the blood samples can be pooled together in a batch of six or eight prior to testing (mini-pool-NAT [MP-NAT]), or the tests can be run on every individual sample (individual donor-NAT [ID-NAT]). It has been debated in various studies whether pooling of samples results in decreased sensitivity of detection as the volume of individual samples gets lesser in a pool. The objective of this study was to investigate the effect of dilution on the sensitivity of tests.Materials and Methods:The study was performesd on nine plasma samples which were hepatitis B reactive exclusively by Procleix Ultrio Plus and not by Procleix Ultrio or serology. These nine exclusive UltrioPlus ID-NAT yield samples were diluted in 1:2, 1:4. 1:6 and 1:8 dilutions using previously tested negative plasma and each dilution of every sample along with archived undiluted sample were retested in three replicates with Procleix Ultrio Plus Assay.Results:Among NAT yield samples, 88.88% of the samples were detected when retested in ID-NAT in undiluted form. Samples with higher viral load (sample 5 and 6) were detected by all dilutions. When samples with viral load below 20 IU/mL were tested in dilutions of 1:6 or 1:8, only 9 out of 27 replicates (33.33%) were detected. This means that more than 67% of low viral load samples were missed by MP-NAT of 1:6 or 1:8 dilution out of total NAT yield samples.Conclusion:Individual Donor NAT is ideal methodology for NAT as dilution due to pooling may miss samples with low viral load as evident in this study.

Prevalence, incidence, risk factors and residual risk associated with viral infections among eligible Brazilian blood donors

“…However, the specificities of such tests are lower than those of NATs and false positive results may be generated owing to crossreactivity between different antigens. [32][33][34] This situation could lead to the discarding of many blood bags, 35,36 the loss of eligible donors and deficiency in the supply of blood. 34 The low number of seronegative samples that were NAT+ detected in the present study (n = 16) is similar to other publications and can be attributed to the low specificity of the serological tests used.…”

“…34 The low number of seronegative samples that were NAT+ detected in the present study (n = 16) is similar to other publications and can be attributed to the low specificity of the serological tests used. [35][36][37][38][39] NAT is relevant for the early detection of viral antigens in the stages immediately following infection, while serological tests are important for detecting antigens and antibodies that may take a few days to appear in the blood. Therefore, the combination of both techniques enhances transfusion safety and quality, as they complement each other.…”

“…However, the specificities of such tests are lower than those of NATs and false positive results may be generated owing to cross‐reactivity between different antigens 32–34 . This situation could lead to the discarding of many blood bags, 35,36 the loss of eligible donors and deficiency in the supply of blood 34 …”

Dengue RNA detection and seroprevalence in blood donors during an outbreak in the São Paulo State, Brazil, 2016

“…In support of this is the observation that DENV load may be relatively low in blood donors. 9 Although pool testing has been related to lower sensitivity in the detection of common blood borne infections like HBV 16 as an important factor remains the pool size. In pools with a low number of assembled samples, the probability of viral F I G U R E 1 Characterization of the main events of the primary DENV infection in blood donors.…”