Long-term persistence after acute Q fever of non-infective Coxiella burnetii cell components, including antigens.

BACKGROUND: Previous studies of inciting factors for a prolonged post-infection fatigue syndrome after Q fever (variously termed QFS or Q fever associated CFS/ME in the literature) showed that after the acute infection a high proportion of asymptomatic and QFS patients had Q fever antibody and also low levels in PBMC and bone marrow of Coxiella burnetii (C.b.) DNA with PCR assays directed against three different target sequences in different parts of the coxiella genome. Attempts to isolate a strain of C.b. in A/J mice, and cell culture from PCR positive PBMC and bone marrow were consistently negative. The detailed composition of the persisting coxiella residues remains to be defined. AIM: To retest and provide detailed results on selected PCR positive samples from the Birmingham Q fever outbreak patients tested by a highly sensitive method to detect viable organisms and to determine the nature of the residual coxiella cell components. DESIGN: Laboratory case study. METHODS: NOD/SCID mice were inoculated with samples from the 1989 Q fever outbreak in Birmingham and followed for evidence of infection and the presence of coxiella DNA and specific antigens in spleen and liver macrophages. A significant, unexpected finding of specific antigen was followed by assessment of its ability to provoke production of inflammatory and non-inflammatory cytokines in mice, in THP-1 human macrophage cell cultures and to induce inflammatory lesions in the skin of guinea pigs hyperimmunized against Q fever vaccine. RESULTS: Culture of samples from 10 Birmingham Q fever patients in NOD/SCID mice, 12 years from infection did not yield viable Coxiella burnetii, as shown earlier. However complexes of material with coxiella antigens were found in mouse spleens in all cases but in significantly greater amounts in samples from those with post Q fever fatigue syndrome. The antigenic complexes [now designated 'immunomodulatory complexes' (IMC)] were shown to stimulate cytokine release in the mice and in the THP-1 macrophages and to provoke an inflammatory reaction on intradermal injection into the skin of Q fever hyperimmunized guinea pigs. CONCLUSION: The study identifies a non-infective complex of C.b. antigens able to survive in the host and provoke aberrant humoral and cell medicated immunity responses - a possible pathogenic link between initial infection and a subsequent long-term post Q fever fatigue syndrome.

Q fever: persistence of antigenic non-viable cell residues of Coxiella burnetii in the host--implications for post Q fever infection fatigue syndrome and other chronic sequelae.

BACKGROUND: Our previous studies of persistence of Coxiella burnetii in humans after an initial acute Q fever infection revealed raised, maintained antibody levels and low levels of coxiella genomic DNA at the age of 5 years from onset in Australian patients and at 12 years in patients in the 1989 Birmingham UK Q fever outbreak. Attempts to isolate the coxiella in standard cell culture and susceptible mice by serial passage of PCR positive PBMC and bone marrow were negative. AIM: To retest PCR positive patient samples by more sensitive methods for viable coxiellas and for the coxiella cell components of antigen and specific lipopolysaccharide (LPS). To re-interpret the previous results in the light of the new information. To review the pertinent literature for a concept of an immuno-modulatory complex generated by the current studies. DESIGN: Laboratory case study. METHODS: Stored patient samples were inoculated into SCID mice that were followed for 60 days. Mouse spleen and liver samples were then examined by PCR assay for targets in the COM1 and IS1111a sequences and for antigens by IFA with a polyclonal rabbit antiserum to C. burnetii Phase 1 and a monoclonal antiserum to Phase 1 LPS (details; O. Sukocheva et al., unpublished data). RESULTS: All specimens, including a recently excised heart valve from a Birmingham patient with late developing endocarditis, were infection negative in SCID mice. Dilutions of SCID mouse spleen and liver homogenates titrated in PCR assays were negative at dilutions attained by control mice inoculated with an endpoint dilution of a viable prototype strain of C. burnetii. Sections of the spleens from all specimens showed a complex of coxiella antigen-LPS by IFA. DISCUSSION/REVIEW: We advance a concept of long-term persistence of a non-infective, non-biodegraded complex of coxiella cell components with its antigens and specific LPS [so called Immunomodulatory complex (IMC)] associated with traces of genomic DNA that signalled its presence in our earlier studies. The IMC's survival in patients for at least 12 years, and in one patient for 70 years implies a capacity for serial passage in macrophages with effective down-regulation of their biodegrading functions. The review assesses the compatibility of the IMC concept in relation to cogent literature on C. burnetii interactions with macrophage and cell-mediated immunity. Some remaining gaps in our knowledge of the organ sites and duration of carriage of viable coxiellas after initial infection are also identified.

Long-term persistence of Coxiella burnetii after acute primary Q fever.

BACKGROUND: Long-term persistence of C. burnetii in infected animals was established in the 1950s and 60s, but the implications for human Q fever are not fully explored. AIM: To compare the prevalence of markers of infection in a cohort of Q fever patients in Australia (up to 5 years after infection) with those in the 1989 Birmingham cohort (12 years after infection). DESIGN: Case follow-up study. METHODS: C. burnetii was tested for by: (i) antibodies to Phase 1 and 2 antigens in the three immunoglobulin classes; (ii) detection of DNA in bone marrow and peripheral blood mononuclear cells by PCR assays directed against several different targets in the genome; and (iii) attempts to isolate coxiellas in cell culture or mice from PCR-positive samples. Amplicon specificity was verified by fluorometric probing and by sequencing. Cross-contamination was excluded by extensive use of non-template controls, and in particular by the use of certain IS1111a target sequences. RESULTS: Irrespective of clinical state, both groups remained seropositive, principally exhibiting medium levels of IgG antibody against C. burnetii Phase 2 antigen. C. burnetii genomic DNA was detected by PCR in 65% of bone marrow aspirates from Australian patients and approximately 88% of Birmingham patients. No coxiella were isolated from PCR positive samples. DISCUSSION: We propose a provisional model for persistence. In Q fever without sequelae, the process is largely confined to the bone marrow. In Q fever fatigue syndrome (QFS), it is modulated by the patient's immunogenetic background to give higher levels of coxiella genomes in bone marrow and increased shedding into the peripheral blood. In Q fever endocarditis, late pregnancy, or during iatrogenic or other immunosuppression, the multiplication cycle is prolonged, and a potential source of live organisms.

Sexually transmitted Q fever.

We report the sexual transmission of Coxiella burnetii from a man with occupationally acquired Q fever to his wife. Fifteen days after coitus, his wife also developed serologically proven acute Q fever. C. burnetii DNA sequences were detected by polymerase chain reaction (PCR) performed on semen samples obtained from the husband at 4 and 15 months after the onset of acute Q fever, but PCR results were variable at 23 months, indicating the presence of few organisms.

Long-term persistence of Coxiella burnetii in the host after primary Q fever.

After a primary infection Coxiella burnetii may persist covertly in animals and recrudesce at parturition to be shed in the products of conception and the milk. Similar latent persistence and recrudescence occurs in man: namely, infection of placenta, heart valve or mural endocardium, bone or liver. The numbers of organisms, their viability and cellular form, and the underlying organ sites of latent infection for the coxiella are obscure. During investigations of 29 patients with a chronic sequel to acute Q fever, the post-Q fever fatigue syndrome (QFS) [1-3], sensitive conventional and TaqMan-based PCR revealed low levels of C. burnetii DNA in blood mononuclear cells (5/29; 17%), thin needle liver biopsies (2/14; 14%) and, notably, in bone marrow aspirates (13/20; 65%). Irrespective of the ultimate significance of coxiella persistence for QFS, the detection of C. burnetii genomic DNA in bone marrow several years after a primary infection unveils a new pathological dimension for Q fever.

An outbreak of Mycobacterium bovis infection in fallow deer (Dama dama).

In an outbreak of Mycobacterium bovis infection in fallow deer in South Australia, 3 herds related by recent movement of deer were infected. From these 3 infected herds, 47 of 51 animals were tuberculosis at necropsy. A range of lesions was seen most of which differed from classical bovine tuberculosis in that pus was a white liquid, fibrous encapsulation was not marked and calcification was rare. Histopathology was of classical tuberculosis. M. bovis was cultured from lesions and M. avium-intracellulare was cultured from one deer with no visible lesions. The source of M. bovis infection has not been determined.