Implementation of donor screening for infectious agents transmitted by blood by nucleic acid...

265

Vox Sanguinis

(2005)

89

, 265

LETTER

©

2005 Blackwell Publishing

Blackwell Publishing, Ltd.Oxford, UKVOXVox Sanguinis0042-90072003 Blackwell Publishing Ltd894265LETTERLetter to the EditorLetter to the EditorLETTER

Implementation of donor screening for infectious agents transmitted by blood by nucleic acid technology in Japan

H.

Yugi, S.

Hino, M.

Satake & K.

Tadodoro

NAT Department of Central Blood Institute, Japanese Red Cross, Tokyo, Japan

Further to the international forum ‘Implementation of DonorScreening for Infectious Agents Transmitted by Blood byNucleic Acid Technology: Update to 2003’ (

Vox Sang

200588: 289–393), we present here the results from Japan.

The Japanese Red Cross Blood Center is the only institute inJapan that deals with blood procurement, processing, testingand delivery in the whole country. In October 1999, it imple-mented nucleic acid amplification testing (NAT) nationwidefor hepatitis B virus (HBV) as well as for hepatitis C virus(HCV) and HIV utilizing the Roche multiplex primer reagent.The entire process from pooling to real-time polymerasechain reaction (PCR) is fully automated. Because the numberof seropositive samples for HBV is so high in Japan, onlyseronegative samples are pooled, demanding the rapid com-pletion of serological testing at local blood centres. We haveso far encountered no cases of cross-contamination betweensamples. Blood aliquots from all donations are sent to threeNAT centres at midnight on the day of blood collection, andthe NAT results are reported to all blood centres the followingmorning or afternoon. No components are released withoutconfirming the NAT results in spite of the situation that plateletconcentrates have an expiration time of 72 h after collection.

After 7 months using the 500-minipool system, we movedto the 50-pool system in February 2000. In August 2004, wefurther decreased the pool size to 20 without altering theexisting logistics and schedule. The increase in the yield ofseronegative but NAT-positive donations was not evident forHIV and HCV as the pool size decreased, but is apparent for

HBV, as confirmed by several donations that were 50-pool-NAT-negative but 20-pool-NAT-positive for HBV. This wouldbe one of the theoretical bases for the implementation of NATwith a smaller pool size for HBV in a country like Japanwhere HBV infection is highly endemic. Around 90% ofNAT-only positive blood samples are considered to be derivedfrom window-period donations although a relatively highyield of NAT-only positive donations can be partly explainedby the lower sensitivity of the HBsAg detection method weuse (agglutination) than that of enzyme immunoassay (EIA)or chemiluminescent immunoassay (CLIA).

As for serological HBV screening, we are currently using acombination of the HBsAg, HBcAb and HBsAb assays. Whilea donor with a low HBcAb titre is accepted, a donation witha high HBcAb titre is qualified only if its HBsAb titre is suf-ficiently high to induce a protective effect (> or = 200 m IU/ml). Although the NAT system is a powerful tool for detectingwindow-period donations and often detects chronic carrierswith a low HBV viral load and fluctuating viraemia, we haveexperienced a considerable number of minipool–NAT break-through cases where HBV infection occurred as a result of thetransfusion of minipool–NAT-negative components or evenindividual donation NAT-negative components.

Received: 19 July 2005,accepted 27 July 2005

H. Yugi (yugi@bs.jrc.or.jp)S. Hino (s-hino@bs.jrc.or.jp)M. Satake (ma-satake@tokyo.bc.jrc.or.jp)K. Tadokoro (k-tadokoro@bs.jrc.or.jp)NAT Department of Central Blood InstituteJapanese Red CrossNakarokugo 3-30-1Oota-kuTokyo 144–0055

Japan