JPAC Joint United Kingdom (UK) Blood Transfusion and Tissue Transplantation Services Professional Advisory Committee

9.3: Specific assays

Update notice:  Section 9.3 - Information has been updated following the the issue of Change Notification 12 - 2016.

9.3.1: HBsAg

  • The UK specification for the minimum level of sensitivity for the performance of HBsAg screening is 0.2 IU/mL. A UK HBsAg working standard (07/288 or equivalent) containing 0.2 IU/mL HBsAg is available from the National Institute for Biological Standards and Control (NIBSC). Laboratories using an assay of high analytical or dilutional sensitivity where the working standard reacts too strongly are advised to utilise the NIBSC HBsAg monitoring standard (07/286 or equivalent) set at 0.05 IU/mL in place of the working standard.
     
  • In addition to the assay manufacturer’s controls, the UK working standard must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of HBsAg test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.2: anti-HIV 1+2 or HIV 1+2 Ag/Ab combination

  • The HIV 1+2 Ag/Ab combination assay is recommended for use within the UK Blood Services as the serological screening assay of choice.
     
  • The UK requirement for the minimum level of sensitivity for the performance of HIV 1+2 serological screening is that a positive result should be obtained with the UK anti-HIV 1 working standard, available from NIBSC (99/750 or equivalent). Laboratories using an assay of higher analytical or dilutional sensitivity where the working standard reacts too strongly are advised to utilise the NIBSC HIV working standard 1/5 dilution (99/710 or equivalent) in place of the working standard. There is no specific requirement to demonstrate individual anti-HIV 2 or HIV p24 Ag reactivity.
     
  • In addition to the assay manufacturer’s controls, the UK working standard must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of HIV test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening, including demonstrating specific anti-HIV 2 reactivity and, as appropriate specific HIV p24 Ag reactivity.

9.3.3: anti-HCV

  • The UK requirement for the minimum level of sensitivity for the performance of anti-HCV screening is that a positive result should be obtained with the UK anti-HCV working standard (06/188 or equivalent), available from NIBSC. Laboratories using an assay of higher analytical or dilutional sensitivity where the working standard reacts too strongly are advised to utilise the NIBSC HCV working standard 1/8 dilution (06/190 or equivalent) in place of the working standard.

     
  • In addition to the assay manufacturer’s controls, the UK working standard must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of anti-HCV test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.4: anti-HTLV I/II

  • The UK requirement for the minimum level of sensitivity for the performance of anti-HTLV I/II screening is that a positive result should be obtained with the UK anti-HTLV working standard, available from NIBSC (03/104 or equivalent).
     
  • In addition to the assay manufacturer’s controls, the UK working standard must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of anti-HTLV I/II test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.5: Syphilis antibody

  • The UK requirement for the minimum level of sensitivity for the performance of syphilis (specific treponemal antibody) screening is that, in the absence of a specifically defined UK working standard produced by NIBSC, a positive result should be obtained with the appropriate Health Protection Agency (HPA) syphilis quality control preparation.
     
  • In addition to the assay manufacturer’s controls, the HPA syphilis quality control preparation must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of anti-treponemal test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.6: Malarial antibody

The exclusion period for donors from malarial areas is given in the Joint UKBTS/HPA Professional Advisory Committee (JPAC) Donor Selection Guidelines.3 These guidelines specify situations where donations may only be released if a test for malarial antibodies is negative.

  • The UK requirement for the minimum level of sensitivity for the performance of malarial antibody (anti-P. falciparum/vivax) screening is that, in the absence of a specifically defined UK working standard produced by NIBSC, a positive result should be obtained with the HPA malaria antibody quality control preparation.
     
  • In addition to the assay manufacturer’s controls, the HPA malaria antibody quality control preparation must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of malarial antibody test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.7: anti-T. cruzi

The deferral criteria for donors from T. cruzi endemic areas are given in the JPAC Donor Selection Guidelines.3 Donors at risk of T. cruzi must be tested for anti-T. cruzi and negative results obtained prior to the release of any donation for clinical use.

  • The UK requirement for the minimum level of sensitivity for the performance of anti-T. cruzi screening is that, in the absence of a specifically defined UK working standard produced by NIBSC, a positive result should be obtained with a formally validated in-house anti-T. cruzi quality control preparation.
     
  • In addition to the assay manufacturer’s controls, the anti-T. cruzi quality control preparation must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of anti-T. cruzi test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.8: anti-HBc

The exclusion period for blood donors who have had body piercing, acupuncture etc. are given in the JPAC Donor Selection Guidelines.3 Certain of these categories may require donations to be tested for anti-HBc and negative results obtained prior to release of any blood component for clinical use. Tissue and stem cells donations have anti-HBc screening as a mandatory requirement.

  • The UK requirement for the minimum level of sensitivity for the performance of anti-HBc screening is that, in the absence of a specifically defined UK working standard produced by NIBSC, a positive result should be obtained with the HPA anti-HBc quality control preparation.
     
  • In addition to the assay manufacturer’s controls, the HPA anti-HBc quality control preparation must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of anti-HBc test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.
     
  • Donations found to be reactive for anti-HBc should be tested for anti-HBs (see section 9.3.10).

9.3.9: anti-HCMV

  • The UK requirement for the minimum level of sensitivity for the performance of anti-HCMV screening is that, in the absence of a specifically defined UK working standard produced by NIBSC, a positive result should be obtained with the HPA anti-HCMV quality control preparation.
     
  • In addition to the assay manufacturer’s controls, the HPA anti-HCMV quality control preparation must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of anti-HCMV test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.10: anti-HBs

Donations found to be reactive for anti-HBc with levels of anti-HBs <100 mIU/mL are deemed unsuitable for release, whereas those with levels >100 mIU/mL can be considered suitable for release.

  • The UK requirement for the minimum level of sensitivity for the performance of anti-HBs testing is that, in the absence of a specifically defined UK working standard produced by NIBSC, a positive result should be obtained with the HPA anti-HBs quality control preparation.
     
  • In addition to the assay manufacturer’s controls, the HPA anti-HBs quality control preparation must be included at least once in each series of tests to demonstrate acceptable sensitivity of the test method.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down.

9.3.11: Hepatitis C virus RNA (HCV NAT)

  • The UK requirement for the minimum level of sensitivity for the performance of HCV NAT is 5000 IU/mL in an individual donation. An HCV international standard is available from the NIBSC.
     
  • The assay must include a specific internal control for each sample tested.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and any additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of HCV RNA test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening

9.3.12: Hepatitis B virus DNA (HBV NAT)

  • There is currently no specific UK requirement for the minimum level of sensitivity for the performance of HBV NAT. An HBV international standard is available from the NIBSC.
     
  • The assay must include a specific internal control for each sample tested.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and any additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of HBV DNA test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.13: Human immunodeficiency virus RNA (HIV NAT)

  • There is currently no specific UK requirement for the minimum level of sensitivity for the performance of HIV NAT. An HIV international standard is available from the NIBSC.
     
  • The assay must include a specific internal control for each sample tested.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and any additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of HIV RNA test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.14: Hepatitis E virus RNA (HEV NAT)

  • There is currently no specific UK requirement for the minimum level of sensitivity for the performance of HEV NAT
     
  • The assay must include a specific internal control for each sample tested
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and any additional quality control samples have satisfied the criteria laid down
     
  • Each manufacturer’s batch/lot of HEV RNA test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening

9.3.15: West Nile virus RNA (WNV NAT)

The exclusion criteria for donors from a WNV risk area is given in the JPAC Donor Selection Guidelines.3 These guidelines specify some situations where donations may only be released if a test for WNV RNA is negative. WNV RNA screening can be performed on donations provided by donors within the exclusion period and the donations released if WNV RNA negative.

  • There is currently no specific UK requirement for the minimum level of sensitivity for the performance of WNV NAT.
     
  • The assay must include a specific internal control for each sample tested.
     
  • No series of tests should be considered acceptable unless the result of the assay manufacturer’s and any additional quality control samples have satisfied the criteria laid down.
     
  • Each manufacturer’s batch/lot of WNV RNA test kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.

9.3.16: Other infectious agents

The JPAC Donor Selection Guidelines3 may identify other infectious agents and specify some situations when screening may be applied in addition to donor deferral. In such situations any screening performed must:

  • use assays specifically evaluated and validated for the screening of the donation type
     
  • identify and utilise an independent quality control in each series of tests in addition to the manufacturer’s assay controls
     
  • ensure that the results of the assay manufacturer’s and the additional quality control samples have satisfied the criteria laid down prior to release of the results
     
  • require that each manufacturer’s batch/lot of kits must be shown to conform with nationally established minimum criteria for specificity and sensitivity prior to being accepted for use for screening.