The obligately intracellular chlamydiae are bacterial pathogens that occupy intracellular vacuoles, termed inclusions, as they develop and multiply. Typical Chlamydia trachomatis isolates occupy inclusions that fuse with other C. trachomatis inclusions within cells infected with multiple elementary bodies (wild-type phenotype). The authors of this study have recently described C. trachomatis isolates that form multiply-lobed, non-fusogenic inclusions within single cells infected with multiple elementary bodies (variant phenotype). Inclusions formed by these isolates uniformly lacked the protein IncA on the inclusion membrane (IM). In the present work, the study of the C. trachomatis inclusion phenotype has been expanded to include 27 variant and 13 wild-type isolates. Twenty-four of the 27 variant isolates were IncA-negative, as detected by fluorescence microscopy and immunoblotting, but three variants localized IncA to the IM. The IncA-positive variants formed inclusions that fused, at a reduced rate, with those occupied by wild-type isolates and with inclusions formed by other IncA-positive variants. Nucleotide-sequence analysis of the incA sequences from the variant isolates identified a variety of distinct sequence polymorphisms relative to incA from wild-type strains. The authors also demonstrate that a second Inc protein, CT223p, is not found in the IM in selected C. trachomatis isolates. No change in the structure or the fusogenicity of the inclusions was associated with the presence or absence of CT223p.
BannantineJ. P.,
RockeyD. D.,
HackstadtT.
1998a; Tandem genes of Chlamydia psittaci that encode proteins localized to the inclusion membrane. Mol Microbiol 28:1017–1026[CrossRef]
BannantineJ. P.,
StammW. E.,
SuchlandR. J.,
RockeyD. D.
1998b; Chlamydia trachomatis IncA is localized to the inclusion membrane and is recognized by antisera from infected humans and primates. Infect Immun 66:6017–6021
BannantineJ. P.,
GriffithsR. S.,
ViratyosinW.,
BrownW. J.,
RockeyD. D.
2000; A secondary structure motif predictive of protein localization to the chlamydial inclusion membrane. Cell Microbiol 2:35–47[CrossRef]
DeanD.,
PattonM.,
StephensR. S.
1991; Direct sequence evaluation of the major outer membrane protein gene variant regions of Chlamydia trachomatis subtypes D′, I′, and L2′. Infect Immun 59:1579–1582
FlingS. P.,
SutherlandR. A.,
SteeleL. N.,
HessB.,
D’OrazioS. E.,
MaisonneuveJ.,
LampeM. F.,
ProbstP.,
StarnbachM. N.
2001; CD8+ T cells recognize an inclusion membrane-associated protein from the vacuolar pathogen Chlamydia trachomatis
. Proc Natl Acad Sci USA 98:1160–1165[CrossRef]
GeislerW. M.,
SuchlandR. J.,
RockeyD. D.,
StammW. E.
2001; Epidemiology and clinical manifestations of unique Chlamydia trachomatis isolates that occupy nonfusogenic inclusions. J Infect Dis 184:879–884[CrossRef]
HackstadtT.,
ScidmoreM. A.,
RockeyD. D.
1995; Lipid metabolism in Chlamydia trachomatis -infected cells: directed trafficking of Golgi-derived sphingolipids to the chlamydial inclusion. Proc Natl Acad Sci USA 92:4877–4881[CrossRef]
HackstadtT.,
RockeyD. D.,
HeinzenR. A.,
ScidmoreM. A.
1996; Chlamydia trachomatis interrupts an exocytic pathway to acquire endogenously synthesized sphingomyelin in transit from the Golgi apparatus to the plasma membrane. EMBO J 15:964–977
HackstadtT.,
Scidmore-CarlsonM. A.,
ShawE. I.,
FischerE. R.
1999; The Chlamydia trachomatis IncA protein is required for homotypic vesicle fusion. Cell Microbiol 1:119–130[CrossRef]
HayesL. J.,
BaileyR. L.,
MabeyD. C. W.,
ClarkeI. N.,
PickettM. A.,
WattP. J.,
WardM. E.
1992; Genotyping of Chlamydia trachomatis from a trachoma-endemic village in the Gambia by a nested polymerase chain reaction: identification of strain variants. J Infect Dis 166:1173–1177[CrossRef]
LampeM. F.,
WongK. G.,
KuehlL. M.,
StammW. E.
1997; Chlamydia trachomatis major outer membrane protein variants escape neutralization by both monoclonal antibodies and human immune sera. Infect Immun 65:317–319
PannekoekY.,
van der EndeA.,
EijkP. P.,
van MarleJ.,
de WitteM. A.,
OssewaardeJ. M.,
van den BruleA. J.,
MorreS. A.,
DankertJ.
2001; Normal IncA expression and fusogenicity of inclusions in Chlamydia trachomatis isolates with the incA I47T mutation. Infect Immun 69:4654–4656[CrossRef]
RidderhofJ. C.,
BarnesR. C.
1989; Fusion of inclusions following superinfection of HeLa cells by two serovars of Chlamydia trachomatis
. Infect Immun 57:3189–3193
RockeyD. D.,
RosquistJ. L.
1994; Protein antigens of Chlamydia psittaci present in infected cells but not detected in the infectious elementary body. Infect Immun 62:106–112
RockeyD. D.,
HeinzenR. A.,
HackstadtT.
1995; Cloning and characterization of a Chlamydia psittaci gene coding for a protein localized in the inclusion membrane of infected cells. Mol Microbiol 15:617–626
ScidmoreM. A.,
HackstadtT.
2001; Mammalian 14-3-3β associates with the Chlamydia trachomatis inclusion membrane via its interaction with IncG. Mol Microbiol 39:1638–1650[CrossRef]
Scidmore-CarlsonM. A.,
ShawE. I.,
DooleyC. A.,
FischerE. R.,
HackstadtT.
1999; Identification and characterization of a Chlamydia trachomatis early operon encoding four novel inclusion membrane proteins. Mol Microbiol 33:753–765[CrossRef]
StephensR. S.,
KalmanS.,
LammelC.9 other authors1998; Genome sequence of an obligate intracellular pathogen of humans: Chlamydia trachomatis
. Science 282:754–759[CrossRef]
SuchlandR. J.,
RockeyD. D.,
BannantineJ. P.,
StammW. E.
2000; Isolates of Chlamydia trachomatis that occupy nonfusogenic inclusions lack IncA, a protein localized to the inclusion membrane. Infect Immun 68:360–367[CrossRef]
YuanY.,
LyngK.,
ZhangY. X.,
RockeyD. D.,
MorrisonR. P.
1992; Monoclonal antibodies define genus-specific, species-specific, and cross-reactive epitopes of the chlamydial 60-kilodalton heat shock protein (hsp60): specific immunodetection and purification of chlamydial hsp60. Infect Immun 60:2288–2296
Diversity within inc genes of clinical Chlamydia trachomatis variant isolates that occupy non-fusogenic inclusionsaaThe GenBank accession numbers for the sequences reported in this paper can be found in Fig. 1F1.