IX. IDENTIFICATION OF MYCOPLASMAS
387
Kanarek, 1960) it appears to give very satisfactory results, it is not used
much at the present time for the identification of mycoplasmas. I n the
field of avian mycoplasmology, various modifications of direct agglutination
are, however, used quite extensively for the demonstration of antibodies
in serum specimens in diagnostic and epidemiological studies of diseases
caused by important avian pathogens such as M . gallisepticum and M.
synoviae (Adler, 1954, 1958; Adler and Yamamoto, 1956; Adler and DaMassa, 1964, 1967; Roberts and Olesiuk, 1967; Hromatka and Adler,
1969). The test seems to be highly specific to the extent that it may even
distinguish between groups of strains within species that show some
degree of heterogeneity, for example M. hominis. The original subdivision
of A . laidlawii into three “types”, A, B and C (Laidlaw and Elford, 1936)
was also based on the agglutination test, although at least “types” A and B
were later shown by other methods to be so very closely related that this
distinction is no longer maintained. The sensitivity of direct agglutination
tests appears to depend on a number of variables (Section V . E, 2).
(e) Indirect agglutination. This technique is employed most widely in the
form of the indirect haemagglutination (IHA) test, using tanned fresh or
either formalinised or glutaraldehyde treated red blood cells coated with
mycoplasma antigen as the agglutinable particles (Ross and Switzer, 1963 ;
Tully, 1963; Dowdle and Robinson, 1964; Taylor-Robinson et al., 1964,
1965a, b ; Adler and DaMassa, 1967b; Lind, 1968; Krogsgaard-Jensen,
1971; Freundt et al., 1973; Holmgren, 1973; Lam and Morton, 1974; Cho
et al., 1976). Latex particles have also been used as antigen carriers (Morton,
1966; Kende, 1969).
The potential suitability of the IHA test for species classification was
particularly borne out by the studies of Tully (1963) and by TaylorRobinson et al. (1964, 1965a) who obtained clear-cut serological distinctions between all of the then established human Mycoplasma species.
I n the study by Tully, the specificity was equal to that of the simple
agglutination and fluorescence antibody techniques and in those by
Taylor-Robinson et al. it was equivalent to or above that of the complement
fixation test. The IHA technique used by the latter authors obviously
resulted in a high degree of sensitivity. Although at the same time crossreactions between species frequently occurred, they were always at l OW
titre and negligible compared with the exceedingly high homologous titres.
Results reported by Freundt et al. (1973b) from an assay of a considerable
number of serum reference reagents for a variety of Mycoplasma and
Acholeplasma species were in general in line with those of Taylor-Robinson
et al., although in some cases heterologous cross-reactivity at fairly hiph
titre was observed when fresh tanned red blood cells were used. The
387
Kanarek, 1960) it appears to give very satisfactory results, it is not used
much at the present time for the identification of mycoplasmas. I n the
field of avian mycoplasmology, various modifications of direct agglutination
are, however, used quite extensively for the demonstration of antibodies
in serum specimens in diagnostic and epidemiological studies of diseases
caused by important avian pathogens such as M . gallisepticum and M.
synoviae (Adler, 1954, 1958; Adler and Yamamoto, 1956; Adler and DaMassa, 1964, 1967; Roberts and Olesiuk, 1967; Hromatka and Adler,
1969). The test seems to be highly specific to the extent that it may even
distinguish between groups of strains within species that show some
degree of heterogeneity, for example M. hominis. The original subdivision
of A . laidlawii into three “types”, A, B and C (Laidlaw and Elford, 1936)
was also based on the agglutination test, although at least “types” A and B
were later shown by other methods to be so very closely related that this
distinction is no longer maintained. The sensitivity of direct agglutination
tests appears to depend on a number of variables (Section V . E, 2).
(e) Indirect agglutination. This technique is employed most widely in the
form of the indirect haemagglutination (IHA) test, using tanned fresh or
either formalinised or glutaraldehyde treated red blood cells coated with
mycoplasma antigen as the agglutinable particles (Ross and Switzer, 1963 ;
Tully, 1963; Dowdle and Robinson, 1964; Taylor-Robinson et al., 1964,
1965a, b ; Adler and DaMassa, 1967b; Lind, 1968; Krogsgaard-Jensen,
1971; Freundt et al., 1973; Holmgren, 1973; Lam and Morton, 1974; Cho
et al., 1976). Latex particles have also been used as antigen carriers (Morton,
1966; Kende, 1969).
The potential suitability of the IHA test for species classification was
particularly borne out by the studies of Tully (1963) and by TaylorRobinson et al. (1964, 1965a) who obtained clear-cut serological distinctions between all of the then established human Mycoplasma species.
I n the study by Tully, the specificity was equal to that of the simple
agglutination and fluorescence antibody techniques and in those by
Taylor-Robinson et al. it was equivalent to or above that of the complement
fixation test. The IHA technique used by the latter authors obviously
resulted in a high degree of sensitivity. Although at the same time crossreactions between species frequently occurred, they were always at l OW
titre and negligible compared with the exceedingly high homologous titres.
Results reported by Freundt et al. (1973b) from an assay of a considerable
number of serum reference reagents for a variety of Mycoplasma and
Acholeplasma species were in general in line with those of Taylor-Robinson
et al., although in some cases heterologous cross-reactivity at fairly hiph
titre was observed when fresh tanned red blood cells were used. The