Biomaterial Database

SINGLE-DOSE ASSAY TECHNIQUE FOR VARIOLA VIRUS. 1964

J M RILEY, and M D ORLANDO

A biological assay for variola virus was needed that would (i) require a minimum of time and (ii) have acceptable precision. Preliminary titrations made in 11-day-old embryonated eggs and in suckling mice (6 to 24 hr of age) demonstrated a linear relationship between the concentration of variola virus injected and the mean reciprocal time to death (MTD) of both hosts. This linear response indicated that the injection of a single dose of virus suspension and the measurement of the MTD should result in an acceptable assay method. Seven replicate samples of liquid preparations (20% chorioallantoic membrane in Heart Infusion Broth) and the freeze-dried material obtained with these suspensions were assayed in triplicate for pock infectious units and for MTD. The variance of the pock counts was far greater than was expected from a Poisson distribution, and coefficients of variation ranged from 25 to 61%. Variances obtained with the single-dilution assay were all far below that expected from a Poisson distribution, and coefficients of variations ranged from 5.2 to 13.6%. The use of the MTD assay resulted in a saving of time, a saving in the number of hosts necessary per assay, and increased precision.

UI	MeSH Term	Description	Entries
D010406	Penicillins	A group of antibiotics that contain 6-aminopenicillanic acid with a side chain attached to the 6-amino group. The penicillin nucleus is the chief structural requirement for biological activity. The side-chain structure determines many of the antibacterial and pharmacological characteristics. (Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1065)	Antibiotics, Penicillin,Penicillin,Penicillin Antibiotics
D012106	Research	Critical and exhaustive investigation or experimentation, having for its aim the discovery of new facts and their correct interpretation, the revision of accepted conclusions, theories, or laws in the light of newly discovered facts, or the practical application of such new or revised conclusions, theories, or laws. (Webster, 3d ed)	Research Priorities,Laboratory Research,Research Activities,Research and Development,Activities, Research,Activity, Research,Development and Research,Priorities, Research,Priority, Research,Research Activity,Research Priority,Research, Laboratory
D002642	Chick Embryo	The developmental entity of a fertilized chicken egg (ZYGOTE). The developmental process begins about 24 h before the egg is laid at the BLASTODISC, a small whitish spot on the surface of the EGG YOLK. After 21 days of incubation, the embryo is fully developed before hatching.	Embryo, Chick,Chick Embryos,Embryos, Chick
D004531	Eggs	Animal reproductive bodies, or the contents thereof, used as food. The concept is differentiated from OVUM, the anatomic or physiologic entity.
D005612	Freeze Drying	Method of tissue preparation in which the tissue specimen is frozen and then dehydrated at low temperature in a high vacuum. This method is also used for dehydrating pharmaceutical and food products.	Lyophilization,Drying, Freeze,Dryings, Freeze,Freeze Dryings,Lyophilizations
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001681	Biological Assay	A method of measuring the effects of a biologically active substance using an intermediate in vivo or in vitro tissue or cell model under controlled conditions. It includes virulence studies in animal fetuses in utero, mouse convulsion bioassay of insulin, quantitation of tumor-initiator systems in mouse skin, calculation of potentiating effects of a hormonal factor in an isolated strip of contracting stomach muscle, etc.	Bioassay,Assay, Biological,Assays, Biological,Biologic Assay,Biologic Assays,Assay, Biologic,Assays, Biologic,Bioassays,Biological Assays
D012901	Variola virus	A species of ORTHOPOXVIRUS causing infections in humans. No infections have been reported since 1977 and the virus is now believed to be virtually extinct.	Poxvirus variolae,Smallpox Virus,Smallpox Viruses,Variola viruses
D013307	Streptomycin	An antibiotic produced by the soil actinomycete Streptomyces griseus. It acts by inhibiting the initiation and elongation processes during protein synthesis.	Estreptomicina CEPA,Estreptomicina Clariana,Estreptomicina Normon,Strepto-Fatol,Strepto-Hefa,Streptomycin Grünenthal,Streptomycin Sulfate,Streptomycin Sulfate (2:3) Salt,Streptomycin Sulphate,Streptomycine Panpharma,Strepto Fatol,Strepto Hefa
D016012	Poisson Distribution	A distribution function used to describe the occurrence of rare events or to describe the sampling distribution of isolated counts in a continuum of time or space.	Distribution, Poisson