Tbx18 Regulates the Differentiation of Periductal Smooth Muscle Stroma and the Maintenance of Epithelial Integrity in the Prostate.

The T-box transcription factor TBX18 is essential to mesenchymal cell differentiation in several tissues and Tbx18 loss-of-function results in dramatic organ malformations and perinatal lethality. Here we demonstrate for the first time that Tbx18 is required for the normal development of periductal smooth muscle stromal cells in prostate, particularly in the anterior lobe, with a clear impact on prostate health in adult mice. Prostate abnormalities are only subtly apparent in Tbx18 mutants at birth; to examine postnatal prostate development we utilized a relatively long-lived hypomorphic mutant and a novel conditional Tbx18 allele. Similar to the ureter, cells that fail to express Tbx18 do not condense normally into smooth muscle cells of the periductal prostatic stroma. However, in contrast to ureter, the periductal stromal cells in mutant prostate assume a hypertrophic, myofibroblastic state and the adjacent epithelium becomes grossly disorganized. To identify molecular events preceding the onset of this pathology, we compared gene expression in the urogenital sinus (UGS), from which the prostate develops, in Tbx18-null and wild type littermates at two embryonic stages. Genes that regulate cell proliferation, smooth muscle differentiation, prostate epithelium development, and inflammatory response were significantly dysregulated in the mutant urogenital sinus around the time that Tbx18 is first expressed in the wild type UGS, suggesting a direct role in regulating those genes. Together, these results argue that Tbx18 is essential to the differentiation and maintenance of the prostate periurethral mesenchyme and that it indirectly regulates epithelial differentiation through control of stromal-epithelial signaling.

A distant downstream enhancer directs essential expression of Tbx18 in urogenital tissues.

The vertebrate T-box transcription factor gene Tbx18 performs a vital role in development of multiple organ systems. Tbx18 insufficiency manifests as recessive phenotypes in the upper urinary system, cardiac venous pole, inner ear, and axial skeleton; homozygous null mutant animals die perinatally. Here, we report a new regulatory mutation of Tbx18, a reciprocal translocation breaking 78kbp downstream of the gene. 12Gso homozygotes present urinary and vertebral defects very similar to those associated with Tbx18-null mutations, but 12Gso is clearly not a global null allele since homozygotes survive into adulthood. We show that 12Gso down-regulates Tbx18 expression in a manner that is both spatially- and temporally-specific; combined with other data, the mutation points particularly to the presence of an essential urogenital enhancer located near the translocation breakpoint site. In support of this hypothesis, we identify a distal enhancer element, ECR1, which is active in developing urogenital and other tissues; we propose that disruption of this element leads to premature loss of Tbx18 function in 12Gso mutant mice. These data reveal a long-range regulatory architecture extending far downstream of Tbx18, identify a novel and likely essential urogenital enhancer, and introduce a new tool for dissecting postnatal phenotypes associated with dysregulation of Tbx18.

Perinatal autopsy rates at the University Hospital of the West Indies: 2002-2008.

OBJECTIVES: High perinatal autopsy rates are necessary for institutional management protocols and national policy-making. This study reviews perinatal autopsy rates and factors affecting these rates at the University Hospital of the West Indies. METHOD: All perinatal deaths (stillborn infants > or = 24 weeks gestation or 500 g; early neonatal deaths ie 0-7 days old) at the University Hospital of the West Indies, between January 2002 and December 2008, were reviewed retrospectively, using the annual perinatal audit records. The annual autopsy rates were calculated and the reasons why autopsies were not done examined. RESULTS: The average stillbirth (SB) autopsy rate was 59.6% (range 51.9 - 76.7%), while that for early neonatal deaths (ENDs) was 47.9% (range 34.4 - 63.2), with an overall average perinatal autopsy rate of 54.0% (range 42.2 - 62.2). Autopsies were requested in 79.3% and 51.7% of SBs and ENDs, respectively. Of those requested, 81.7% were done (75.2% stillbirths; 92.5% ENDs). In the ENDs, failure to request an autopsy was predominantly noted in premature infants weighing < 1000 g (75.2% of those not requested). In stillbirths, the reasons for failure to request were largely unknown with failure to gain permission accounting for only 20.3% of these cases. CONCLUSIONS: The average annual perinatal autopsy rate at the University Hospital of the West Indies between 2002 and 2008 was 54.0%. This is below the internationally recommended rate of 75%. Failure to request an autopsy was the most significant factor contributing to this. The reasons for this are not entirely clear and require further study.

Perinatal autopsy rates at the University Hospital of the West Indies: 2002-2008 / Tasas de autopsia perinatal en el Hospital Universitario de West Indies: 2002-2008

OBJECTIVES: High perinatal autopsy rates are necessary for institutional management protocols and national policy-making. This study reviews perinatal autopsy rates and factors affecting these rates at the University Hospital of the West Indies. METHOD: All perinatal deaths (stillborn infants > 24 weeks gestation or 500 g; early neonatal deaths ie 0-7 days old) at the University Hospital of the West Indies, between January 2002 and December 2008, were reviewed retrospectively, using the annual perinatal audit records. The annual autopsy rates were calculated and the reasons why autopsies were not done examined. RESULTS: The average stillbirth (SB) autopsy rate was 59.6% (range 51.9 - 76.7%), while that for early neonatal deaths (ENDs) was 47.9% (range 34.4 - 63.2), with an overall average perinatal autopsy rate of 54.0% (range 42.2 - 62.2). Autopsies were requested in 79.3% and 51.7% of SBs and ENDs, respectively. Of those requested, 81.7% were done (75.2% stillbirths; 92.5% ENDs). In the ENDs, failure to request an autopsy was predominantly noted in premature infants weighing < 1000 g (75.2% of those not requested). In stillbirths, the reasons for failure to request were largely unknown with failure to gain permission accounting for only 20.3% of these cases. CONCLUSIONS: The average annual perinatal autopsy rate at the University Hospital of the West Indies between 2002 and 2008 was 54.0%. This is below the internationally recommended rate of 75%. Failure to request an autopsy was the most significant factor contributing to this. The reasons for this are not entirely clear and require further study.

OBJETIVOS: Las altas tasas autopsia perinatal son necesarias para los protocolos institucionales de tratamiento, y el establecimiento de políticas a nivel nacional. Este estudio examina las tasas de autopsia perinatal y los factores que afectan estas tasas, en el Hospital Universitario de West Indies. MÉTODO: Todas las muertes perinatales (mortinatos > 24 semanas de gestación o 500 g; muertes neonatales tempranas, es decir, 0-7 días de nacido) en el Hospital Universitario de West Indies, entre el 2002 de enero y el 2008 de diciembre, fueron sometidas a examen retrospectivo, usando los registros de auditoría perinatales anuales.Las tasas de autopsia anuales fueron calculadas y se analizaron las razones por las que no se hicieron autopsias. RESULTADOS: La tasa de autopsia promedio de mortinatos (MN) fue 59.6% (rango 51.9-76.7%), mientras que la tasa de autopsia promedio de las muertes neonatales tempranas (MNT) fue 47.9% (rango 34.4-63.2), con una tasa promedio general de autopsia perinatal de 54.0% (rango 42.2-62.2). Se requirieron autopsias en 79.3% y 51.7% de los MN y las MNT respectivamente. De las autopsias requeridas, se realizaron 81.7% (75.2% mortinatos; 92.5% MNT). En relación con las MNT, la no solicitud de autopsia se notó predominantemente en infantes prematuros de peso < 1000 g (75.2% de aquéllos no solicitados). Con respecto a los mortinatos, se desconoce en gran medida las razones por las que no se hizo una solicitud, excepto el no haber obtenido permiso, lo cual explica sólo el 20.3% de los casos. CONCLUSIONES: La tasa de autopsia perinatal promedio anual en el Hospital Universitario de West Indies entre 2002 y 2008 fue 54.0%. Esta cifra se halla por debajo de la tasa internacionalmente recomendada de 75%. La no solicitud de una autopsia fue el factor más significativo que contribuyó a ello. Las razones para esto no están completamente claras y requieren estudio posterior.

Validation of quantitative ELISAS for measuring anti-Yersinia pestis F1 and V antibody concentrations in nonhuman primate sera.

This study systematically validated two quantitative enzyme-linked immunosorbent assays (ELISAs) for determining Yersinia pestis anti-F1 or anti-V IgG concentration in cynomolgus macaque sera. The results demonstrated that these ELISAs are reliable, reproducible, and suitable for their intended use to measure both anti-F1 and anti-V IgG in monkey sera following vaccination with a heterologous recombinant fusion F1-V protein (rF1-V). Statistical analysis demonstrated assay precision, accuracy, specificity, linearity/dilutional linearity, and robustness for both assays. The quantitative ranges of standard curves were defined as 40-700 ng/mLfor both anti-F1 and anti-V IgG. Either serological assay could be used to determine potency of F1/V antigen-based vaccines in surrogate clinical studies or to define correlates of protective immunity against plague under the Food and Drug Administration's (FDA) two-animal rule.

Germline mutation in BRAF codon 600 is compatible with human development: de novo p.V600G mutation identified in a patient with CFC syndrome.

BRAF, the protein product of BRAF, is a serine/threonine protein kinase and one of the direct downstream effectors of Ras. Somatic mutations in BRAF occur in numerous human cancers, whereas germline BRAF mutations cause cardio-facio-cutaneous (CFC) syndrome. One recurrent somatic mutation, p.V600E, is frequently found in several tumor types, such as melanoma, papillary thyroid carcinoma, colon cancer, and ovarian cancer. However, a germline mutation affecting codon 600 has never been described. Here, we present a patient with CFC syndrome and a de novo germline mutation involving codon 600 of BRAF, thus providing the first evidence that a pathogenic germline mutation involving this critical codon is not only compatible with development but can also cause the CFC phenotype. In vitro functional analysis shows that this mutation, which replaces a valine with a glycine at codon 600 (p.V600G), leads to increased ERK and ELK phosphorylation compared to wild-type BRAF but is less strongly activating than the cancer-associated p.V600E mutation.

Age is an independent risk factor for left atrial dysfunction: results from an observational study.

Introduction. The degenerative changes of myocardial tissue are thought to influence left atrial (LA) function. Changes of left atrial function are generally due to changes in left ventricle (LV) compliance. But valvular dysfunction and hypertension as comorbidity cannot be ignored. Women have a different clinical profile compared with men concerning the risk of heart failure. We investigated the influence of increasing age and gender corrected for comorbidity, on left atrial function.Methods. Using an open access echocardiography database, supplemented with additional LA function measurements, we defined three different LA function parameters. Odds ratios (OR) were calculated to reproduce the relation between age, gender and LA function. The association between age, gender and LA function was estimated, and corrected for comorbid conditions as valve disease, high blood pressure and LV dysfunction, using logistic regression.Results. Higher age was positively correlated with increased LA volume, decreased ejection fraction and increased LA kinetic energy. Age per decade increase, corrected for comorbidity, resulted in an increased risk of LA dysfunction (OR between 1.5 and 1.9). Gender had little influence on LA function parameters except for LA maximal volume. Men had a significantly larger LA maximal volume compared with women. Conclusions. In this open access echocardiography database, increasing age was correlated with LA dysfunction. Age per decade increase, corrected for comorbid conditions such as mitral and aortic valve disease, hypertension and heart failure, is an independent risk factor for LA dysfunction. The gender influence on LA dysfunction seems to be limited. (Neth Heart J 2010;18:243-7.).

The Dutch experience of open access echocardiography.

Cardiac disease is not easy to recognise in general practice. An echocardiogram is an excellent way to provide information about left ventricular mass and diastolic (dys)function and the presence of valvular heart disease. To improve diagnostic care of cardiac patients, an open access echocardiography service was established in the referral area of our hospital, where general practitioners were able to ask for an echocardiogram without referring the patient to the cardiologist. Between December 2002 and October 2006 echocardiograms were requested for 471 patients. Thirteen percent of the patients referred for dyspnoea and 3% of patients with a cardiac murmur had a left ventricular ejection fraction <40%. In 28% of patients no cardiac abnormality could be found. If we looked at the prevalence of hypertension in the referred patients, this was very high with a prevalence of up to 60% in the older age groups. If we included hypertension in the analysis, only 16% of patients had no structural cardiac or vascular abnormality. The study shows that the advantage of open access echocardiography in the Netherlands is that the general practitioner is able to make a better diagnosis and unnecessary referrals of patients with suspected cardiac disease can be avoided. (Neth Heart J 2007;15:342-7.).

Open access echocardiography is feasible in the Netherlands.

OBJECTIVES: In an urban region in the Netherlands, general practitioners (GPs) were offered an open access echocardiographic service. We report the outcomes of the first two years of this project. METHODS: GPs were given a course on the indications and restrictions for diagnostic referral as well as the interpretation of echocardiographic results. Indications were restricted to `dyspnoea', `cardiac murmur' and `peripheral oedema'. A uniform request form was developed, using ticking boxes for quick completion. The echocardiogram was performed within one week after the request. Results were interpreted by the cardiologist according to the criteria of the Dutch, European and American Societies of Echocardiography. RESULTS: Sixty GPs from 43 general practices participated, covering a practice population of 130,000 persons. During a period of 24 months, 198 patients were referred. Only 1.5% of the workload of the echocardiography department was due to requests from GPs. The GPs kept well to the agreements on indications for echocardiography (91% approved reasons). An abnormal echocardiographic outcome was found in 53% of all patients. For `cardiac murmur' this was 52%, for `dyspnoea' 63%, and for `peripheral oedema' 58%. Left ventricular dysfunction was present in 49 patients (25%); diastolic dysfunction was present in most of them (39 patients, 19%). Systolic dysfunction (LVEF < 40%) was found in 19 patients (10%). Twenty patients (10%) appeared to have relevant aortic or mitral valve disease. CONCLUSION: GPs did not overuse the open access echocardiographic service; they possibly used it conservatively. To prevent underdiagnosis of left ventricular dysfunction, diagnostic strategies in which electrocardiogram, NT-pro-BNP and echocardiography are combined, should be developed.

Short- and long-term efficacy of single-dose subunit vaccines against Yersinia pestis in mice.

A single, subcutaneous, 30-microg dose of either a combination of the Yersinia pestis proteins F1+V or a F1-V fusion protein adsorbed to the adjuvant aluminum hydroxide, protected Hsd:ND4 mice for one year against pneumonic plague. The recombinant F1+V vaccine provided significant protection as early as day 14 postimmunization. The current Plague Vaccine USP in a single 0.2-ml dose did not provide significant protection in this mouse model. Antibody titers to F1 and V peaked at approximately 5-12 weeks postimmunization and were still detectable one year later. These F1 and V subunit vaccines may offer effective long-term immunity with a reduced dosage schedule when compared with the presently licensed, formalin-killed, whole-cell vaccine.

The influence of the milieu on the rate of neutralisation of herpes simplex virus 1.

The rate of neutralisation of herpes simplex virus 1 was increased by up to more than five hundred-fold when the virus suspension and antiserum were each diluted to one hundred-fold in water instead of phosphate buffered saline. This phenomenon, which was observed for two human positive sera and a rabbit purified polyclonal antibody, may represent an unrecognised homeostatic mechanism where neutralising antibody is 'dilution-fast' under physiological conditions of transudation or pathological conditions of inflammation.

Protection of mice from fatal bubonic and pneumonic plague by passive immunization with monoclonal antibodies against the F1 protein of Yersinia pestis.

Monoclonal antibodies (MAbs) to the fraction 1 (F1) protein of Yersinia pestis protected mice against fatal pneumonic as well as bubonic plague from wild-type F1+ organisms. The rare isolation of a virulent F1- isolate from surviving animals supports earlier studies suggesting that improved vaccines should consist of immunogens to protect against F1- variants. The high degree of protection with IgG MAb suggests that secretory IgA is not required for protection from pneumonic plague.

Pore-forming activity of Coxiella burnetii outer membrane protein oligomer comprised of 29.5- and 31-kDa polypeptides. Inhibition of porin activity by monoclonal antibodies 4E8 and 4D6.

Envelopes of large-cell variant Coxiella burnetii, the agent of Q fever, were the starting material for purification of an outer membrane protein (OMP) oligomer with aggregate molecular mass of approximately 2 x 10(4) kDa. The oligomer was resistant to trypsin and dissociation by SDS at 100 degrees C. Reducing agents dissociated the oligomer into monomers of 29.5 and 31 kDa, which migrated as a doublet during SDS-polyacrylamide gel electrophoresis. Both monomers were reactive in an immunoblot assay with monoclonal antibodies (mAbs) 4E8 and 4D6, which were previously selected for their reactivity with purified and SDS-denatured 29.5 kDa protein. Proteoliposomes were functional in an equilibrium assay at pH 7 and a swelling assay at pH 7 and 4.5. The pores in proteoliposomes allowed the passage of arabinose, glucose, and sucrose, but restricted stachyose. Polyclonal antibodies to C. burnetii cells and the mAbs were able to bind C. burnetii at pH 7 and 4.5. The uptake of 14C-glucose at pH 4.5 was inhibited by polyclonal antibodies and mAbs after binding to cells at pH 7. The mAbs did not inhibit 14C-glucose uptake at pH 4.5 after binding to cells at pH 4.5. Although the mAbs bind C. burnetii porin epitopes before and after acid activation, the mAbs bound under acidic conditions were unable to inhibit porin function. The inhibition of porin channel function by mAbs confirms the role of porin as a permeability barrier for the subsequent active transport of glucose by C. burnetii. In another study, we showed that the 29.5 kDa OMP antigen induced active immunity against virulent challenge. This information, combined with the recent confirmation that porins are important antigens in the induction of specific protective immune responses against infection by gram-negative bacteria, suggests that humoral immunity directed against C. burnetii porins might play an important role in immunity against Q fever (human infection) and coxiellosis (animal infection), global enzootic diseases.

Isolated acute occlusion of a large right ventricular branch of the right coronary artery following coronary balloon angioplasty. The only true 'model' to study ECG changes in acute, isolated right ventricular infarction.

An isolated right ventricular infarction occurs rarely and data on its electrocardiographic appearance and underlying angiographically proven cause are scarce. The electrocardiographic response of acute right ventricular ischaemia is often obscured by the coexisting forces of the ischaemic mass of the inferior wall of the left ventricle when the right coronary artery itself becomes occluded. Percutaneous transluminal coronary angioplasty of the right coronary artery may cause an isolated occlusion of a right ventricular branch. We encountered this phenomenon in nine patients. In all, it led to acute isolated right ventricular ischaemia with ST elevations in the right precordial leads (V1-V3, V3R and V4R) on the electrocardiogram. We conclude that the ECG pattern of pure right ventricular ischaemia can be seen when an isolated occlusion of a large right ventricular branch occurs, for example as a complication of percutaneous transluminal coronary angioplasty.

Cell-mediated and humoral immune responses after vaccination of human volunteers with the live vaccine strain of Francisella tularensis.

The specific humoral and cell-mediated immune responses of human volunteers vaccinated with the Francisella tularensis live vaccine strain (LVS) were evaluated. In the search for an optimal antigen to measure the immunogenicity of the vaccine in an enzyme-linked immunosorbent assay, we tested irradiation-killed LVS, an aqueous ether extract of the LVS (EEx), lipopolysaccharide (LPS) from LVS, and a virulent strain (SCHU4). Volunteers were immunized with LVS by scarification. Immunoglobulin G (IgG) responses to LVS and LPS gave the highest background titers when tested with sera from unimmunized volunteers, whereas IgA, IgG, and IgM background titers to EEx and SCHU4 were low. Vaccination caused a significant rise (P < 0.01) in IgA, IgG, and IgM titers to all antigens tested, except for the IgG response to LPS. Eighty percent of vaccinated volunteers developed a positive IgG response to EEx 14 days postvaccination, while 50% were positive to LVS. By day 14 after vaccination, 70% of immunized volunteers exhibited a positive response to EEx in an in vitro peripheral blood lymphocyte proliferation assay. EEx, a specific and sensitive antigen for evaluating immune responses of vaccinated volunteers, may be a superior antigen for the diagnosis of tularemia.

Platelet Membrane Glycoprotein IIb/IIIa has Sequence Homologies with Human Virus Proteins and Synthetic Viral Peptides Inhibit Anti-GPIIb/IIIa Antibodies in Autoimmune Thrombocytopenic Purpura.

Human platelet GP IIb/IIIa and common human viruses showed sequence homologies of up to 220 amino acids. High scoring homologies were found in Herpes Simplex, Varicella Zoster, Epstein-Barr virus, Adenovirus and Cytomegalovirus, all of which cause lifelong latent infections. Further high scoring sequences were found in Measles, Mumps and Rubella, which are sporadically associated with acute autoimmune thrombocytopenic purpura (AITP). Lower scoring homologies were found in Parvovirus, coxsackie B and Human Immunodeficiency Virus. There were frequent homologies to known autoantibody-binding epitopes in the cysteine-rich and intracytoplasmic regions of GP IIb/IIIa, but also with the RGD-binding and calcium-binding regions, and with the nascent GP signal peptide which is not expressed in the functional glycoprotein. Peptides representing the 48 highest scoring viral sequences were synthesised in vitro, and 7 of these viral peptides were shown to inhibit the serum autoantibodies of adults with chronic AITP. The pattern and degree of autoantibody inhibition varied from patient to patient, was concentration dependent and distinct for each peptide. This suggests that polyclonal GP IIb/IIIa autoantibodies are directed to different GP epitopes and are cross reactive in different patients to different viral proteins in different viruses. The results suggest that human viruses have a role in the aetiology of AITP via molecular mimicry of platelet GP IIb/IIIa, and that chronic auto immunity may be related to a persistent antigenic stimulus from lifelong latent viral infections.

Immunotherapy of tularemia: characterization of a monoclonal antibody reactive with Francisella tularensis.

An IgM monoclonal antibody (mAb) recognized surface antigens specific to Francisella tularensis wild-type (Schu4) and live vaccine strain (LVS), and reacted with both in ELISA and slide agglutination tests. This mAb also reacted with LVS microorganisms in tissues of infected mice as assessed by an indirect fluorescence technique. Western blot analysis showed the mAb to react with antigens associated with F. tularensis LPS.

Cell-mediated and humoral immune responses induced by scarification vaccination of human volunteers with a new lot of the live vaccine strain of Francisella tularensis.

Tularemia is a disease caused by the facultative intracellular bacterium Francisella tularensis. We evaluated a new lot of live F. tularensis vaccine for its immunogenicity in human volunteers. Scarification vaccination induced humoral and cell-mediated immune responses. Indications of a positive immune response after vaccination included an increase in specific antibody levels, which were measured by enzyme-linked immunosorbent and immunoblot assays, and the ability of peripheral blood lymphocytes to respond to whole F. tularensis bacteria as recall antigens. Vaccination caused a significant rise (P less than 0.05) in immunoglobulin A (IgA), IgG, and IgM titers. Lymphocyte stimulation indices were significantly increased (P less than 0.01) in vaccinees 14 days after vaccination. These data verify that this new lot of live F. tularensis vaccine is immunogenic.

Antigenic structure of Coxiella burnetii. A comparison of lipopolysaccharide and protein antigens as vaccines against Q fever.

The antigenic structure of Coxiella burnetii is being investigated by identifying both external and internal cellular epitopes of the morphologic cell types. Both the phase I lipopolysaccharide (LPSI) and several surface proteins are candidates for the development of subunit multivalent vaccines. The protective efficacy of purified LPSI was demonstrated in A/J mice. The purified LPSI preparations contained residual peptides detected by amino acid analysis. Therefore, the protection afforded by LPSI may be, in part, due to the presence of peptides. The purification of proteins free of LPSI must be accomplished before the protective efficacy of proteins or peptides can be established. We have identified three proteins that are both antigenic and immunogenic, as indicated by either enzyme immunoassay, radioimmunoprecipitation, immunoblot assay, or lymphocyte transformation. A 62-kDa protein antigen encoded by the htpB gene of C. burnetii was analyzed for immunogenicity. The purified protein antigen was immunogenic, as it elicited specific antibodies and performed as recall antigen in lymphocyte stimulation assays. The antigen was not detected on the surface of phase I cells but was highly represented on the surface of phase II cells. Therefore, the protein may not be a good candidate for vaccine development. The diagnostic utility of the 62-kDa protein antigen lies in the fact that convalescent and chronic Q fever sera from human patients reacted with the antigen, whereas acute sera did not. Although the 62-kDa protein is a "common antigen," specific peptide-based diagnostic reagents may be useful in the detection of Q fever disease progression. A major surface protein (P1) of roughly 29.5 kDa was purified from the phase I Nine Mile (clone 7) strain. No LPSI was detected in the P1 preparation by three different LPSI monoclonal antibodies. Monoclonal antibodies prepared against P1 were effective in localizing the protein on the cell surface, in the cell wall, and associated with the peptidoglycan of large cells of C. burnetii. Small, pressure-resistant cells did not contain P1. Mice immunized with two 25-micrograms injections of LPSI produced antibodies against LPSI and phase I whole cells. No antibody was detected against phase II whole cells. Immunization with P1 induced antibody against the LPSI fraction and phase I and phase II whole cells. P1 was more effective than LPSI in reducing the number of infectious C. burnetii in the spleens of challenged mice. The gene encoding another protein (P2) recognized by P1 monoclonal antibodies was cloned and sequenced.(ABSTRACT TRUNCATED AT 400 WORDS)