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UK/CORP/15-0012l. Date of preparation: July 2015
United Kingdom
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Plasma Testing

CSL Behring was the first biopharmaceutical company to conduct NAT/PCR testing of source plasma for the following five viruses: human immunodeficiency virus (HIV), Hepatitis A (HAV), Hepatitis B (HBV), Hepatitis C (HCV) and Parvovirus B19 (B19V). Inventory hold ensures that units testing positive during the window period1 are destroyed.

Nucleic Acid Amplification Technology (NAT) testing allows certain viruses to be detected even before a donor displays any symptoms or develops antibodies. NAT works by detecting the genetic material of a virus like HIV. This very sensitive screening can detect viruses far earlier than serological testing.

Polymerase chain reaction (PCR) is a type of NAT used to amplify specific regions of a DNA or RNA strand via enzymatic replication without using a living organism (such as E. coli or yeast).

NAT/PCR Testing

Window Period for Detection of Viral Infection Serology Testing (Days) NAT/PCR
HAV RNA N/A 12
HBV DNA 59 34
HCV RNA 82 23
HIV-1 RNA 22 11
B19V DNA N/A 7

*N/A (not applicable) since serology testing is not reliable for these viruses. NAT/PCR is used instead.

Serology is the process of testing for antibodies to specific viruses. Seroconversion is the development of specific antibodies to microorganisms in the blood serum due to infection or immunisation. Prior to seroconversion, the blood test is seronegative for the antibody; after seroconversion, the blood test is seropositive for the antibody.

Serology Testing

Tests for Antigens or Antibodies
CSL Behring
Regulatory Requirements
HIV-1 & 2 Yes Yes
Hepatitis C (HCV) Yes Yes
Hepatitis B (HBV) Yes Yes
Syphilis (only for certain donations) Yes Yes
Serum protein electrophoresis Yes Yes
Total amount of antibodies Yes No
Tetanus, varicella zoster virus, hepatitis A virus (HAV)* Yes No

*For these antigens, a positive test is desired in order to manufacture high quality immunoglobulins/hyperimmunoglobulins.

Plasma Testing

Samples from each plasma unit are shipped to one of CSL Plasma’s state-of-the-art testing laboratories. CSL Plasma uses highly sensitive tests to check each sample for evidence of specific blood-borne viruses. These tests include serology tests and nucleic acid amplification technology/polymerase chain reaction (NAT/PCR) tests. A failed unit will be destroyed, and the donor will be permanently deferred.

Nucleic Acid Amplification Technology (NAT) detects the genetic material of a transfusion-transmitted virus including HIV before the body has time to form antibodies. This sensitive screening technique detects viruses earlier than serological testing.

Plasma Pool Testing

At each site, units of plasma are combined into a plasma pool. Each plasma pool is tested for the presence of viruses. A pool is released for further processing based on non-reactivity to serological viral markers (HIV antibodies and Hepatitis B antigens) and virus genome (HAV RNA2, HBV DNA3, HCV RNA, HIV-1 RNA and high titer B19V DNA).

Prior to further processing, each plasma pool is tested for the presence of viruses. The plasma is only used if it is non-reactive for the listed serological markers and for the virus genome. We test each plasma pool for the following serological markers: anti-HIV 1, anti-HIV 2 and hepatitis B surface antigens. In other words, we test each plasma pool for HIV antibodies, Hepatitis B antigens and Hepatitis C antibodies. We also test each plasma pool for the following virus genomes using NAT/PCR testing: Hepatitis A virus, Hepatitis B virus, Hepatitis C virus, HIV-1, B19 virus.

Serological Markers Virus Genome (NAT for DNA or RNA)
HIV-1 antibodies Hepatitis A Virus*
HIV-2 antibodies Hepatitis B Virus
Hepatitis B antigens Hepatitis C Virus (mandatory in EU)
Hepatitis C antibodies HIV-1
  B19 Virus*

*Some plasma pools are not NAT-tested for Hepatitis A or B19 virus.

Inventory Hold, Look-back & Traceability

Inventory hold is a voluntary industry initiative that allows for the retrieval of any suspect donations before they are used. Units (donations) of plasma and donors can be traced through lot numbers using the Donor Management System.

While a plasma sample is tested, the unit is held at a Plasma Logistics Centre before it is released for manufacturing. Inventory hold helps minimise the chance of viruses entering the plasma pool by discarding the plasma of a donor who tests positive for a viral marker at a subsequent donation during the holding period. This assures us that the first donation was not made during the window period for a virus infection: the time between infection and the development of laboratory evidence of the infection through serology or NAT. Only plasma from qualified, i.e. repeat donors is suitable for manufacturing. In this way, we make sure that only units that meet all our stringent specifications are sent to manufacturing sites.

If new information becomes available regarding a donor’s health status, previous donations from that individual, stored in inventory hold, can be retrieved and destroyed prior to pooling for fractionation, via this ‘look-back’ process. This process helps ensure that the highest quality plasma is used in producing plasma-derived therapies.

1A window period for detecting viral infection is the interval between initial viral infection and subsequent detection. For serology testing, the window period is dependent upon the time necessary for antibodies to appear. In NAT/PCR testing, the window period is dependent upon the time necessary for viral nucleic acids (RNA) to manifest.
2RNA (ribonucleic acid) consists of a strain of nucleotides used in gene expression. RNA is the genetic material present in most viruses.
3DNA (deoxyribonucleic acid) is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses.

UK/CORP/15-0012b Date of preparation: July 2015