V-Z

vaccines Preparations that elicit an immune response (production of antibodies) to protect a person or animal from a disease-causing agent.

vacuolation In cell and tissue culture, excess fluid, debris (aggregates), or gas (from sparging) can form inside a cell vacuole, a cavity within the cell that can be relatively clear and fluid filled, gas filled (as in a number of blue-green algae), or food filled (as in protozoa).

validation 1. Documented evidence that shows that an assay or process, when operated within specified ranges of critical parameters, has a high probability of meeting specifications. 2. The process of determining the degree of validity; the procedures involved in checking data for correctness, compliance with standards, and conformance with the requirement specifications. A series of experiments performed using a pre-approved protocol that will generate adequate documented evidence to support a claim of a validated state.

vCJD Variant Creutzfeld-Jakob disease; a fatal neurological disease in humans, believed to be caused by infection with a prion that also causes bovine spongiform encephalopathy (BSE) or "mad cow disease" in cattle. CJD, or classical CJD, is not caused by the BSE agent, and its etiology is unknown.

vector The plasmid, virus, or other vehicle used to carry an r-DNA sequence into the cell of another species.

venture capital Also risk capital; money invested in a small, young, or start-up company that is perceived to have excellent growth prospects but without other access to capital markets. Venture capitalists generally supply capital in return for substantial equity and/or a seat on the board of directors. Sometimes, they provide management and other financial support to their investee companies.

Vero An established cell line derived from the kidney of the African green monkey.

vessel jacket A temperature control method consisting of a double wall outside the main vessel wall. Liquid or steam flows through the jacket to heat (or cool) the fluid in the vessel. Because biopharmaceutical products are so sensitive and vessel jackets can cause uneven heating (hot or cold spots), shell-and-tube or plate-and-frame heat exchangers are more common in biopharmaceutical production systems.

viability The extent to which cells and tissues are living. Cells can be metabolically viable even if they are not reproductively viable.

viral clearance step Process step which separates a given class of virus, if any are present, from the desired product. A clearance factor may be estimated by performing scaled-down experiments using a model virus, to determine process capability.

viral inactivation step Process step, which inactivates the activity of a given class of virus to provide assurance of safety. An inactivation factor may be estimated by performing scaled-down experiments using a model virus, to determine process capability.

virus The simplest form of life: RNA or DNA wrapped in a shell of protein, sometimes with a means of injecting that genetic material into a host organism (infection). Viruses cannot reproduce on their own, but require the aid of a host (bacteria, plant, or animal). The host cell's synthesis is often inhibited by the infecting virus, which may or may not result in disease (more than 200 viruses are known to produce human disease). An individual virus particle is called a virion, and virions vary in structure, complexity, and size (ranging from 20 to 25 nm or less to 2,000 nm or more). Six classes of virus are defined by whether they are single or double stranded, DNA or RNA, or positive or negative.

virus-like particles Also RVLP (retrovirus-like particles); particles that resemble retroviruses, yet lack infectivity, and usually are found in established lines of mammalian cells. Cell bank characterization seeks to determine whether viral activity is present, as a means of assessing risk. Not present in nonmammalian cells or cell lines.

viscosity Thickness of a liquid; determines its internal resistance to shear forces.

warning letter The most serious FDA post-audit (after inspection) letter, notifying a manufacturer of adverse inspection findings and giving it 15 days to reply with a concrete plan for remediation. May or may not be associated with other actions, such as injunction, consent decree, or product seizure.

washing (of a column) Flushing a column with a large volume of a solvent or buffering agent before selective elution of the desired analyte.

well-characterized A chemical entity whose identity, purity, impurities, potency, and quantity can be determined and controlled; most well-characterized biologics are recombinant DNA-derived proteins or monoclonal antibodies.