Medical Definition of R antigen

1. Those that produce active haemolysins (O and S) which cause a zone of clear haemolysis on the blood agar medium in the area of the colony; beta-haemolytic streptococci are divided into groups (A to O) on the basis of cell wall C carbohydrate (see Lancefield classification); Group A (in the strains pathogenic for man) comprises more than 50 types (designated by Arabic numerals) determined by cell wall M protein, which seems to be associated closely with virulence and is produced chiefly by strains with matt or mucoid colonies, in contrast to nonvirulent, glossy colony-producing strains; other surface protein antigens such as R and T (T substance), and the nucleoprotein fraction (P substance) seem to be of less importance. The more than 20 extracellular substances elaborated by strains of beta-haemolytic streptococci include erythrogenic toxin (elaborated only by lysogenic strains), deoxyribonuclease (streptodornase), haemolysins (streptolysins O and S), hyaluronidase, and streptokinase. Synonym: haemolytic streptococci. (05 Mar 2000)

Lexicographical Neighbors of R Antigen

RVF
RVP
RVed
RVing
RVs
RWA
RWD
RWDs
RXVRG endoprotease
R & B
R & D
R Us
R acid
R and B
R and R
R antigen (current term)
R body
R enzyme
R loop
R plasmid
R plasmids
R recombinase
R wave
Raaya
Rab28 GTPase
Rab29 GTPase
Rab geranylgeranyltransferase
Rabaul Creole German

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