Serum antibody response to Chlamydia trachomatis TroA and HtrA in women with tubal factor infertility.

Persistent genital chlamydial infection may lead to tubal factor infertility (TFI). Chlamydia trachomatis TroA and HtrA are proteins expressed during persistent chlamydial infection in vitro. We studied serum IgG antibody response against these proteins by EIA in women with TFI and in subfertile women without tubal pathology. Altogether, 22 of 258 subfertile women (8.5%) had TFI which was unilateral in 17 cases and bilateral in 5 cases. Overall, 55 (21.3%) of the 258 women had TroA and 39 (15.1%) had HtrA antibodies. Seropositivity to TroA and HtrA was more common among women with TFI than women with other causes for subfertility (45.5 vs. 19.1%, p = 0.004 for TroA; 36.4 vs. 13.1%, p = 0.004 for HtrA). Mean absorbance values and the prevalence of TroA and HtrA antibodies increased with increasing severity of TFI. On the basis of our results, TroA and HtrA serology has the potential to be further developed to a specific biomarker for C. trachomatis-related TFI.

Molecular Evidence of Chlamydia-Like Organisms in the Feces of Myotis daubentonii Bats.

Chlamydia-like organisms (CLOs) are recently identified members of the Chlamydiales order. CLOs share intracellular lifestyles and biphasic developmental cycles, and they have been detected in environmental samples as well as in various hosts such as amoebae and arthropods. In this study, we screened bat feces for the presence of CLOs by molecular analysis. Using pan-Chlamydiales PCR targeting the 16S rRNA gene, Chlamydiales DNA was detected in 54% of the specimens. PCR amplification, sequencing, and phylogenetic analysis of the 16S rRNA and 23S rRNA genes were used to classify positive specimens and infer their phylogenetic relationships. Most sequences matched best with Rhabdochlamydia species or uncultured Chlamydia sequences identified in ticks. Another set of sequences matched best with sequences of the Chlamydia genus or uncultured Chlamydiales from snakes. To gain evidence of whether CLOs in bat feces are merely diet borne, we analyzed insects trapped from the same location where the bats foraged. Interestingly, the CLO sequences resembling Rhabdochlamydia spp. were detected in insect material as well, but the other set of CLO sequences was not, suggesting that this set might not originate from prey. Thus, bats represent another potential host for Chlamydiales and could harbor novel, previously unidentified members of this order. IMPORTANCE: Several pathogenic viruses are known to colonize bats, and recent analyses indicate that bats are also reservoir hosts for bacterial genera. Chlamydia-like organisms (CLOs) have been detected in several animal species. CLOs have high 16S rRNA sequence similarity to Chlamydiaceae and exhibit similar intracellular lifestyles and biphasic developmental cycles. Our study describes the frequent occurrence of CLO DNA in bat feces, suggesting an expanding host species spectrum for the Chlamydiales As bats can acquire various infectious agents through their diet, prey insects were also studied. We identified CLO sequences in bats that matched best with sequences in prey insects but also CLO sequences not detected in prey insects. This suggests that a portion of CLO DNA present in bat feces is not prey borne. Furthermore, some sequences from bat droppings not originating from their diet might well represent novel, previously unidentified members of the Chlamydiales order.

Antibody to Chlamydia trachomatis proteins, TroA and HtrA, as a biomarker for Chlamydia trachomatis infection.

We studied whether antibody to two chlamydial proteins (TroA and HtrA) could be used as biomarkers of Chlamydia trachomatis infection. METHODS: Recombinant proteins C. trachomatis TroA and HtrA were used as antigens in enzyme immunoassay (EIA). Both IgG and IgA antibody responses were studied. RESULTS: IgG or IgA antibody to either protein was infrequently detected in sera from healthy blood donors or virgin girls. Patients attending the STI Clinic and patients with perihepatitis had often IgG antibody against TroA (25 and 50 % respectively) and HtrA (21 and 38 % respectively). Especially in sera from patients with chlamydial perihepatitis, the A450nm values with TroA were high (mean 1.591). A positive correlation between C. trachomatis MIF antibody and TroA (r  = 0.7) as well as HtrA (r  = 0.5) antibody was observed in sera from STI clinic patients and perihepatitis patients. Individuals with C. trachomatis infection and positive serology already when seeking medical attention had higher A450nm values for TroA (0.638) and HtrA (0.836) than patients with no marker of previous exposure or with no infection (0.208 and 0.234 respectively). Diagnosis of genital C. trachomatis infection is often NAAT-based, whereas serology has little value in testing for uncomplicated genital C. trachomatis infection. TroA and HtrA antibodies are potential biomarkers for evaluation of ascending and repeated C. trachomatis infection.

Genoprevalence in human tissues of TT-virus genotype 6.

TT virus (TTV) is a newly discovered human virus of high genotypic diversity. TTV is widely distributed among humans, but the possible genotype-related differences in TTV biology are not well known. The prevalence and amount of TTV-DNA, especially of genotype 6, was determined by nested-PCR in various human tissues, and human parvovirus B19, another ssDNA virus, was used as a reference. TTV DNA was detected simultaneously in bile, peripheral blood mononuclear cells (PBMC) and plasma of 77% subjects, in 38% skin samples, in 38% synovial samples and in all (100%) adenoids, tonsils and liver samples. The relative concentrations of TTV-DNA did not vary significantly among the different samples. Genotype 6 TTV-DNA was detected in bile and plasma of one subject (3%), in skin and serum of one subject (8%) and in one liver (5%). The overall prevalence of TTV genotype 6 was 4% in subjects and 4% in sera. TTV genotype 6 was shown to occur in human tissues with no obvious tissue-type or symptom specificity. Parvovirus B19 DNA was detected overall in 38% subjects, and bile was the only sample type tested that did not persistently harbour B19 DNA.

T helper cell-mediated in vitro responses of recently and remotely infected subjects to a candidate recombinant vaccine for human parvovirus b19.

T cell proliferation to human parvovirus B19 antigen was measured in 6 patients with recent B19 infection (1 with pneumonia and pleuritis), 1 patient with symptoms persisting >180 days after onset, 18 nonsymptomatic subjects with remote B19 immunity, and 12 B19-seronegative control subjects. Recombinantly expressed virus-like particles (VP1/2 capsids), a candidate B19 vaccine, were used as antigen. Virus-specific T helper cell proliferation was detectable in all the recently infected patients and in most (17/18) of the remotely infected subjects but not in the seronegative control subjects. The B19-specific T cell responses, in general, were most vigorous among the recently infected patients. However, such strong B19-specific proliferation was not confined within the acute phase, as 28% (5/18) of the remotely infected healthy individuals had B19-specific reactivity persisting at acute-phase levels, apparently for years or decades. These data indicate that B cells recognizing the VP1/2 capsids receive class II-restricted help from CD4(+) T lymphocytes.

Integrity and full coding sequence of B19 virus DNA persisting in human synovial tissue.

Primary infection by human parvovirus B19 is often accompanied by arthropathy of varying duration, of which the most severe cases can be indistinguishable from rheumatoid arthritis (RA). While this might seem to imply a role in RA pathogenesis, recent studies have verified long-term persistence of B19 DNA in synovial tissue not only in patients with rheumatoid or juvenile arthritis, but also in immunocompetent, non-arthritic individuals with a history of prior B19 infection. However, the latter data are based on PCR amplification of short segments of DNA, with little sequence information. We determined the nucleotide sequence and examined the integrity of the protein-coding regions of B19 genomes persisting in synovial tissue and compared the results with data from synovial tissues of recently infected patients. In synovium of both previously and recently infected subjects, the viral coding regions were found to be present in an apparently continuous, intact DNA molecule. Comparison with sequences reported from blood or bone marrow showed that the synoviotropism or persistence of the B19 virus DNA was not due to exceptional mutations or particular genotype variants. The synovial retention of full-length viral genomes may represent a physiological process functioning in long-term storage of foreign macromolecules in this tissue.

Acute-phase-specific heptapeptide epitope for diagnosis of parvovirus B19 infection.

The major capsid protein VP2 of human parvovirus B19, when studied in a denatured form exhibiting linear epitopes, is recognized exclusively by immunoglobulin G (IgG) antibodies of patients with acute or recent B19 infection. By contrast, conformational epitopes of VP2 are recognized both by IgG of the acute phase and by IgG of past immunity. In order to localize the VP2 linear epitope(s) specific for acute-phase IgG, the entire B19 capsid protein sequence was mapped by peptide scanning using well-characterized acute-phase and control sera. A unique heptapeptide epitope showing strong and selective reactivity with the acute-phase IgG was detected and characterized. By using this linear epitope (VP2 amino acids 344 to 350) and virus-like particles exhibiting conformational VP2 epitopes, an innovative approach, second-generation epitope-typing enzyme immunoassay, was set up for improved diagnosis of primary infections by human parvovirus B19.