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Emerging Infections: Microbial Threats to Health in the United States
polymerase chain reaction
a laboratory method of amplifying low levels of specific microbial DNA or RNA sequences.
polymorphic
appearing in different forms.
prevalence
as used in epidemiology, the total number of cases of a disease in existence at a specific time and within a well-defined area; the percentage of a population affected by a particular disease at a given time.
provirus
the genome of a virus integrated into the chromosome of the host cell. It is transmitted to all daughter cells.
Q
quasispecies
a mixture of distinct but closely related viral genomes that exists in a virus-infected individual.
R
recombination
the formation of new combinations of genes as a result of crossing over (sharing of genes) between structurally similar chromosomes, resulting in progeny with different gene combinations than in the parents.
reservoir
any person, animal, arthropod, plant, soil, or substance (or combination of these) in which an infectious agent normally lives and multiplies, on which it depends primarily for survival, and in which it reproduces itself in such manner that it can be transmitted to a susceptible vector.
retrovirus
any of a large family of RNA virtuses that includes lentiviruses and oncoviruses, so called because they carry reverse transcriptase.
reverse transcriptase
RNA-directed DNA polymerase; an enzyme, such as is found in the human immunodeficiency virus, that catalyzes the reaction that uses RNA as a template for double-stranded DNA synthesis.
RNA
ribonucleic acid.
RNA virus
a virus that contains RNA as its genetic material.
S
selective pressure
pressure exerted on an organism by its environment that causes a change in the organism's ability to cope with that environment.
septicemia, septicemic
systemic disease associated with the presence and persistence of microorganisms in the blood.
seroconversion
the change of a serologic test result from negative to positive as a result of antibodies induced by the introduction of microorganisms into the host.
serological
the use of immune serum in any of a number of tests (agglutination, precipitation, enzyme-linked immunosorbent assay, etc.) used to measure the response (antibody titer) to infectious disease; the use of serological reactions to detect antigen.