title: Sensitivity of individual and mini-pool nucleic acid testing assessed by dilution of hepatitis B nucleic acid testing yield samples.
abstract: BACKGROUND
  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.
  
  
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Transfusion Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Kabita
authors.initials: K
authors.lastname: Chatterjee
authors.affiliation: Department of Transfusion Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Nitin
authors.initials: N
authors.lastname: Agarwal
authors.affiliation: Department of Transfusion Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Poonam
authors.initials: P
authors.lastname: Coshic
authors.affiliation: Department of Transfusion Medicine, All India Institute of Medical Sciences, New Delhi, India.
authors.forename: Mayuri
authors.initials: M
authors.lastname: Borgohain
authors.affiliation: Hemogenomics Pvt. Ltd, Bangalore, India.
authors.forename: Sourit
authors.initials: S
authors.lastname: Chakroborty
keywords: Hepatitis B surface antigen; hepatitis B virus; nucleic acid testing; pooling of samples