
PDA Technical Glossary
PDA Technical Reports are highly valued membership benefits because they offer expert guidance and opinions on important scientific and regulatory topics and are used as essential references by industry and regulatory authorities around the world. These reports include terms which explain the material and enhance the reader’s understanding.
The database presented here includes the glossary terms from all current technical reports. The database is searchable by keyword, topic, or by technical report. Each definition provided includes a link to the source technical report within the PDA Technical Report Portal.
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- TR 50: Alt. Methods Mycoplasma Testing (7)
- TR 41: Virus Filtration (7)
- TR 47: Virus Spikes/Virus Clearance (6)
- TR 51: Biological Indicators (2)
- TR 55: TBA/TCA Detection Mitigation (2)
- TR 70: Cleaning/Disinfection Programs (2)
- TR 15: Validation: TFF in Biopharmaceuticals (2)
- TR 45: Depth Filtration (2)
- TR 66: Single-Use Systems (1)
- TR 67: Objectionable Microorganisms (1)
- TR 69: Bioburden/Biofilm Management (1)
- TR 71: Emerging Methods for Virus Detection (1)
- TR 3: Validation: Dry Heat (1)
- TR 83: Virus Contamination in Biomanufacturing: Risk Mitigation, Preparedness, and Response (1)
- TR 88: Microbial Data Deviation Investigations in the Pharmaceutical Industry (1)
- TR 28: Process Simulation for Bulk API (1)
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Adverse Event (AE) Report
An AE report is a communication to the U.S. FDA of an undesirable sign or symptom associated with use of a drug as required and detailed by 21 CFR 314.80. These reports are logged into the U.S. FDA’s Adverse Event Reporting System (AERS). Drug manufacturers are required to report adverse event information to FDA. These reports may also may be voluntarily submitted to the FDA directly by healthcare professionals or the general public at Med Watch. The reports are reviewed, safety issues are monitored, and data are periodically analyzed and assessed by the Center for Drug Evaluation and Research (CDER). (TR55)
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Adverse Trend
A series of alert-level or action-level excursions that indicates the system or areas are not in control and have the potential to affect the product quality. (TR 70)
An increase in the frequency of alert- and action-level excursions or repeated recovery of low levels of microorganisms below the alert level during microbial monitoring or of pharmaceutical ingredient or finished product failure that is indicative of a loss of process control. (TR88)
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Aggregation
Clumping of proteins, viruses, or bacteria that may arise from several mechanisms and may be classified in numerous ways, including soluble/insoluble, covalent/noncovalent, reversible/irreversible, and native/denatured. (TR47)
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Animal-Derived Raw Materials (Primary)
Contains in the final raw material or uses in the manufacturing process of the final raw material, any raw material derived directly from bovine or other animal tissues, for example, bovine serum, porcine-derived trypsin, and animal-tissue-derived hydrolysates. (TR83)
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Biomethylation
The enzyme chlorophenol o-methyltransferase responsible for fungal methylation has been isolated in cell-free extracts. Biomethylation, in this context, may be seen as a detoxification mechanism, although it plays a role in the production of mycotoxins by secondary metabolism. Slightly xerophilic fungi frequently associated halophenol biomethylation include Trichoderma longibrachiatum, Trichoderma virgatum, Aspergillus sydowii, and Penicillium islandicum. (TR55)
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Closed System
An isolated system that has no interaction with its external environment, preventing contamination and release of the material contained.(TR28) (TR 66)
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Dynamic Light Scattering (DLS)
A technique used to measure the size and size distribution of particles. Particles suspended in a solution will cause scattering of light and the extent of the scattering is related to the size and shape of the particles. (TR47)
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Endpoint PCR
A classical PCR method based on repeated cycling of the reaction mixture between two or three temperatures (denaturing, annealing, and extension) with detection of the amplified product after reaction completion (e.g., by agarose gel electrophoresis). (TR50)
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Focus Forming Unit (FFU)
A measure of virus infectively based on formation of a region or “focus”, of infected cells within a monolayer culture that is caused by viruses that do not kill their host, but rather transform them. The number of foci is directly correlated to the number of infectious virus particles. (TR47)
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Frank (Canonical) Pathogens
Microorganisms responsible for infection in healthy individuals (i.e., individuals with normal operative and functional host defense mechanisms) that may be acquired from exposure to other infected people or animals, environmental reservoirs (exogenous) or the individual’s normal (endogenous) microbial flora. (TR67)
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Genome Copy (GC)
An amount of nucleic acid equivalent to the genetic complement present in the genome of a single microorganism. (TR50)
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Genotypic
Relating to those characters that reside in the genetic complement of a specific strain of a specific organism. (TR51)
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Latent Virus
Latency is the ability of a virus to be dormant (latent) within a cell (for example, genetic episomes; provirus). Under certain conditions the virus may become active and produce particles. (TR71)
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Lenticular Filters
A filter made up of a series of biconvex cells that are stacked on top of one another with rings between them to prevent bypass between the cells. End-caps are then placed at the top and bottom of the assembly and are held in place with a central core. [Synonyms: Lenticular Cartridge, Modules, Filter Elements, Filter Devices] (TR45)
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Master Cell Bank (mCb)/Master Virus Bank (mVb)
A stock of cells or virus used to produce the Working Cell Bank or the Working Virus Bank. Cell/virus banking is used to enhance biological consistency. (TR47)
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Matrix Spike Control
An internal control in which an amplifiable amount of nucleic acid is added to a test article to determine inhibition of the PCR. This addition is usually performed pre-extraction and should provide a weak signal 100% of the time. Also known as “interference control”. (TR50)
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Media
The part of the filter through which fluid passes that retains particles during filtration. (TR45)
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Melting Temperature (Tm)
The calculated or observed temperature for a primer/nucleic acid mixture at which 50% of primer-binding sites are in single strand form. (TR50)
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Monodispersed particles
Particles of uniform size in a dispersed phase. In the case of viruses, this term refers to free virus particles not agglomerated to other viruses or proteins in solution. (TR41)
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Most Probable Number (MPN) Method
A statistical method of estimating the number of viable organisms suspended in a liquid. (TR51)
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Nominal Molecular-Weight Cutoff (NMWCO)
A manufacturer’s measure of an ultrafiltration membrane based on a defined solute-retention coefficient. (TR15)
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Nominal Pore Size Rating
A filter rating with an arbitrary value, indicating a particulate size range at which the filter manufacturer claims the filter removes some percentage. Nominal ratings vary from manufacturer to manufacturer and may not be suitable to compare filters among manufacturers. Processing conditions, such as operating pressure and concentration of contaminant may have a significant effect on the retention efficiency of the nominally rated filters. (TR41)
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Plaque Forming Unit (PFU)
A measure of virus infectively based on formation of a region, or “plaque” of lysed cells within a monolayer culture caused by viruses that kill and disrupt their host cell. The number of plaques is directly correlated to the number of infectious virus particles. (TR47)
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Plasmid
An extra-chromosomal DNA molecule in bacteria which is capable of replicating independently of the host chromosomal DNA. Plasmids are often used as positive controls for NAT assays. (TR50)
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Polymerase Chain Reaction (PCR)
A technique widely used in molecular biology in which a DNA polymerase is used to amplify a piece of DNA by in vitro enzymatic replication. As PCR progresses, the DNA thus generated is itself used as a template for replication. This sets in motion a chain reaction in which the DNA template is exponentially amplified. This technique may be used to quantify virus. (TR41) (TR47)
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Process Characterization of Viral Clearance
Viral clearance studies in which nonspecific model viruses are used to assess the general virus clearance capacity of the manufacturing process to remove and/or inactivate viruses. (TR41)
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Process Evaluation Studies of Viral Clearance
Viral clearance studies in which relevant and/or specific “model” viruses are used to determine the ability of the manufacturing process to remove and/or inactivate these viruses. (TR41)
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Pyrogen
Any substance capable of eliciting a febrile (or fever) response upon injection or infection (as in endotoxin released in vivo by Gram-negative bacteria. (TR3) Fever-producing substance (TR69) A material that elicits a pyrogenic response (fever). (TR70)
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Q-PCR Probe
A synthetic, chemically-labeled single-stranded nucleic acid complementary to a selected sequence within a DNA sequence to be amplified using forward and reverse primers in a Q-PCR reaction. A probe is typically labeled with both a fluorophor and quencher. The latter inhibits fluorescence until the quencher and fluorophore are separated by the exonuclease activity of DNA polymerase. (TR50)
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Relevant Virus
A virus used in process evaluation studies that either is the identified virus, or of the same species as the virus known to or likely to contaminate the cell substrate or any other reagents or materials used in the production process. (TR41)
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Reverse Transcriptase PCR (RT-PCR)
A technique for amplifying a defined segment of a RNA molecule. The RNA is first reverse-transcribed into complementary DNA (cDNA), followed by amplification of the cDNA using PCR. (TR50)
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Stirred-Cell Filtration
A surrogate for tangential flow filtration where shear is achieved by rapidly stirring the solution immediately adjacent to the membrane. Typically the stirring is accomplished by mechanical means, such as through the use of a stir bar or impeller. (TR15)
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Surrogate Fluid
A model process fluid used in a small-scale validation study. The fluid is intended to either match or resemble an actual process fluid as closely as is feasible. (TR41)