Characterization of a Strain of Mycoplasma hominis Lacking 120 kDa Membrane Protein Isolated from Vero Cell Culture

Abstract

A strain of Mycoplasma hominis lacking a major membrane protein of 120 kDa was isolated from a Vero cell culture. This strain showed very slow growth rate and formed nipple-less colonies on agar medium.Strains of Mycoplasma hominis have been frequently isolated from various sites in humans, especially from the urogenital tracts (6,15,16), and from cell cultures (2, 11). In general, they require 2 to 3 culture days to reach maximum numbers of the viable organisms in liquid medium, and form fried-egg-like colonies on agar medium. A mycoplasma strain, H-4, was isolated as a contaminant of a Vero cell culture, and was identified as a strain of M. hominis by metabolism inhibition and growth inhibition tests. It grew very slowly compared with those of PG21 (the type strain) and two other clinical isolates of M. hominis and formed nipple-less colonies on agar medium. Then we compared the protein profiles of the cell membrane of the strain H-4 with other M. hominis strains including the type strain for the species.As the strain H-4 metabolized arginine, using eight antisera for arginineutilizing Mycoplasma species which are frequently isolated from cell cultures (2, 11), the metabolism inhibition and growth inhibition tests were performed (Table 1). Among eight antisera, only anti-M. hominis PG21 serum inhibited the metabolism and growth of the strain H-4; therefore, the strain H-4 was identified as M. hominis. The strain H-4 showed a similar extent of the growth under both aerobic and anaerobic conditions, but no improvement of the growth rate by the supplement of yeast extract into media. It showed no hemadsorption, and was sensitive to digitonin like other strains of M. hominis.These findings served to confirm the identification of the strain H-4. However, the strain H-4 required 6 to 7 culture days to reach maximum growth in liquid medium (Fig. 1), and formed nipple-less colonies on agar medium (Fig. 2). These characters of the H-4 did not change even after 15 passages.Four strains of M. hominis were used in cell protein analyses : the strain H-4, the type strain PG21, and two clinical isolates which were referred to as Miya-1 423

The Vlp system of Mycoplasma hyorhinis: combinatorial expression of distinct size variant lipoproteins generating high-frequency surface antigenic variation

“…Second, it is difficult to reconcile a subunit model with (i) the oscillating switches involving single-size versions of distinct Vlps, (ii) the presence of only single-size versions of different Vlps during concomitant expression, or (iii) the ladder anomalies that persist in a particular lineage of size variants. We suggest that a set of translation products analogous to the M. hyorhinis Vlp system could provide an equally plausible alternative to the subunit model of the V-1 system and further suggest that heterogeneous surface antigen systems described in Ureaplasma urealyticum (36a, 41), in Mycoplasma hominis (8,30), and in Mycoplasma arthritidis (40) may also reflect multiple products structurally analogous to the Vlp system of M. hyorhinis. Metabolic labeling, definition of distinct switched lineages, or pulsechase protocols to confirm (or rule out) assembly of subunits will be needed to further characterize these other systems.…”

Evidence that mycoplasmas, gram-negative bacteria, and certain gram-positive bacteria share a similar protein antigen

“…In the course of studies on the characterization of membrane proteins of Mycoplasma hominis (8), a specific antibody directed against a 45-kDa membrane protein, which is one of the major membrane-associated proteins of M. hominis, showed strong cross-reactions with membrane-associated proteins of about 42 to 48 kDa of some Mycoplasma species. The cross-reactivity of a specific antibody against a 43-kDa membrane protein of M. fermentans with some mycoplasmal and bacterial strains was investigated.…”

Mycoplasma genitalium and Mycoplasma pneumoniae Share a 67 Kilodalton Protein as a Main Cross‐Reactive Antigen

“…Protein band of 67 kDa is shown by the arrow. Using rabbit sera diluted to 1: 500 and ascitic fluid (MAb) diluted to 1: 1,000, Western blotting was done as previously described (14). Table 1.…”

“…1, 67 kDa protein of both strains showed strong immunogenicity in rabbits , but few or no antibodies to this protein were observed in sera from patients with M . pneumoniae infection (data Using rabbit sera diluted to 1: 500 and ascitic fluid (MAb) diluted to 1: 1,000, Western blotting was done as previously described (14). Table 1.…”

“…The cells were washed and plated in 24-well plates. First screening of positive hybridomas was performed by ELISA using plates coated with M. pneumoniae cell lysates, and hybridomas secreting antibodies specific to 67 kDa protein were identified by Western blots by modifications of the method of Towbin et al (17), as previously described (14). Cloned cell lines that were stable and were good producers of MAbs were injected intraperitoneally into BALB/c mice pretreated with pristane to produce ascitic fluid.…”