Importancia de las proteínas OmpA y OmpB en el desarrollo de vacunas contra la Rickettsiosis / Importance of OmpA and OmpB proteins in the development of vaccines against rickettsiosis

RESUMEN Las rickettsiosis son un grupo de enfermedades zoonóticas causadas por bacterias del género Rickettsia, transmitidas por ectoparásitos hematófagos. Debido a su cuadro clínico inespecífico (fiebre, artralgias, mialgias y exantema) es subdiagnosticada y confundida con otras de mayor prevalencia como son el dengue y Chikunguya. Dada su creciente incidencia, se han estudiado antígenos rickettsiales, así como la respuesta inmune que generan con el fin de poder desarrollar vacunas, de ellos los más destacados son las proteínas OmpA y OmpB; en recientes estudios se muestra una respuesta inmune efectiva contra esta enfermedad, por lo que la presente revisión tiene como objetivo brindar un panorama de los resultados obtenidos en estudios enfocados al desarrollo de vacunas a partir de estas proteínas.

ABSTRACT Rickettsioses are a group of zoonotic diseases caused by bacteria of the genus Rickettsia, transmitted by hematophagous ectoparasites. Due to its non-specific clinical characteristics (fever, arthralgia, myalgias and exanthema) is underdiagnosed and confused with others of greater influence such as Dengue, and Chikunguya. In attention to its increasing incidence, rickettsial antigens have been studied along with the immune response they generate, in order to develop vaccines against rickettsiosis, being OmpA and OmpB the most prominent. Recent studies indicate an effective immune response against this disease, so the present review aims to provide an overview of the results obtained in studies focusing in vaccine development using these two proteins.

Detección y caracterización molecular de Chlamydia psittaci y Chlamydia abortus en psitácidos mascotas en la provincia de Buenos Aires, Argentina / Detection and molecular characterization of Chlamydia psittaci and Chlamydia abortus in psittacine pet birds in Buenos Aires province, Argentina

In order to determine the presence and genetic diversity of Chlamydia spp. in the north-eastern area of Buenos Aires province, Argentina, conjunctival, oropharyngeal, cloacal swab and tissues were collected from a total of 90 psittacine pet birds of different age and clinical manifestations. Through molecular methods, Chlamydiaceae was detected in 30% (27/90) of the samples, out of which 70.3% (19/27) were positive for Chlamydia psittaci and 14.9% (4/27) for Chlamydia abortus. Nine C. psittaci positive samples were genotyped by ompA gene sequences, 8 clustered within genotype A and 1 within genotype B. A significant association was observed between the presence of Chlamydia spp. and the manifestation of clinical signs compatible with chlamydiosis, as well as with the age of the birds (younger than one year old). This report contributes to the improvement of our understanding of chlamydial agents in our country.

Con el objetivo de determinar la presencia de Chlamydia spp. en psitácidos del área noreste de la provincia de Buenos Aires y conocer su diversidad genética, se recolectaron y analizaron mediante métodos moleculares hisopados conjuntivales, orofaríngeos, cloacales y tejidos de un total de 90 psitácidos de diferentes edades y con diversas manifestaciones clínicas. El 30% (27/90) de las muestras procesadas fueron positivas para Chlamydiaceae; el 70,3% (19/27) de estas resultaron positivas para Chlamydia psittaci y el 14,9% (4/27) para Chlamydia abortus. Nueve muestras positivas para C. psittaci fueron genotipificadas por secuenciación del gen ompA: 8 correspondieron al genotipo Ay una al genotipo B. Se observó una asociación significativa entre la presencia de Chlamydia spp. y la manifestación de signos clínicos compatibles con clamidiosis, como así también con la edad de las aves (menores de un ano). Este informe contribuye a mejorar nuestro conocimiento de los agentes clamidiales en nuestro país.

Distribution of Rickettsia spp. in Ticks from Northwestern and Southwestern Provinces, Republic of Korea

This study was done to characterize distribution of Rickettsia spp. in ticks in the northwestern and southwestern provinces in the Republic of Korea. A total of 2,814 ticks were collected between May and September 2009. After pooling, 284 tick DNA samples were screened for a gene of Rickettsia-specific 17-kDa protein using nested PCR (nPCR), and produced 88 nPCR positive samples. Of these positives, 75% contained 190-kDa outer membrane protein gene (ompA), 50% 120-kDa outer membrane protein gene (ompB), and 64.7% gene D (sca4). The nPCR products of ompA, ompB, and sca4 genes revealed close relatedness to Rickettsia japonica, R. heilongjiangensis, and R. monacensis. Most Rickettsia species were detected in Haemaphysalis longicornis. This tick was found a dominant vector of rickettsiae in the study regions in the Republic of Korea.

Frecuencia de Chlamydia trachomatis en mujeres de edad fértil al usar PCR en tiempo real en el Servicio de Laboratorio del Hospital Carlos Andrade Marín / Recurrence of Chlamydia Trachomatis in women of childbearing age when using CRP in real time in the Laboratory Department of Carlos Andrade Marin Hospital

Introducción: Chlamydia trachomatis es una bacteria patógena comúnmente reportada como causante de infecciones del tracto urogenital. Materiales y métodos: Mediante este estudio se determinó la frecuencia de infección por C. trachomatis utilizando PCR en tiempo real en mujeres de edad fértil (18 ­ 45) que acudieron al laboratorio del Hospital Carlos Andrade Marín. Para el estudio se colectaron 200 muestras de orina y se identificó el patógeno utilizando un kit comercial que identificó el plásmido críptico y al gen ompA presentes en la bacteria. Resultados: Se detectaron 3 muestras positivas que correspondieron al 1.5% de frecuencia. Los casos positivos se encontraron dentro de grupo de edad de 25 a 26 años. Discusión: Los resultados obtenidos en la presente investigación son comparables con estudios similares realizados en Latinoamérica con grupos de bajo riesgo.

Introduction: Chlamydia trachomatis is a pathogenic bacterium commonly reported as cause of infections of the urogenital tract. Methods: This study determined the frequency of C. trachomatis infection using real-time PCR. Two hundred urine samples from women in reproductive age were analyzed (range: 18 ­ 45 years old), which have attended at Carlos Andrade Marín Hospital. In order to test the samples, a commercial kit that identifies the criptic plasmid and the ompA gene from C. trachomatis was used. Results: From the 200 samples, three were positive that corresponed to a frequency of 1.5%. All positive cases were found within the group of 25 and 26 years old. Discussion: The results obtained in this research are comparable with similar studies obtained in several Latin American countries in low risk population

Bioinformatics analysis of Stenotrophomonas maltophilia outer membrane protein OmpA / 军事医学

Objective To predict and analyze the structure and function of Stenotrophomonas maltophilia OmpA. Methods Bioinformatics software and biological databases were used to analyze the physicochemical properties, signal peptides,and transmembrane structures of the OmpA protein and to predict the subcellular localization, secondary and tertiary structures,sequence homology and conserved domains,and epitopes of OmpA.Results OmpA protein had strong hydrophilicity but without transmembrane helices in mature protein,and positions 1-22 of the sequence were predicted as signal peptide.In the second structure random coil helix,αlpha-helix,beta-turn and extended strand made up 50.27%, 24.59%,9.29%and 15.85%,respectively.The three-dimensional structure was β-barrel.OmpA was highly conserved among S.maltophilia strains but shared minimal homology with human and mouse proteins.The N-terminal domain of OmpA was OM-channels superfamily and the C-terminal domain of OmpA was OmpA_C-like superfamily.OmpA protein contained 11 dominant antigen epitopes.Conclusion The characteristics of OmpA identified by bioinformatics analysis can not only provide reference for the study of the structure and novel function of OmpA,but also theoretically contribute to the research on related new subunit vaccines.

Detection and characterization of Chlamydophila psittaci in asymptomatic feral pigeons (Columba livia domestica) in central Thailand

OBJECTIVE@#To detect and characterize Chlamydophila psittaci (C. psittaci) in asymptomatic feral pigeons in central Thailand.@*METHODS@#A total 814 swabs from the trachea and cloacae of 407 non-clinical feral pigeons in central Thailand were collected and tested for the presence of C. psittaci.@*RESULTS@#A 10.8% of feral pigeons in the sample group were positive as determined by nested PCR primer specific to C. psittaci. The outer membrane protein A (ompA) gene of positive samples exhibited amino acid identity of C. psittaci ranging from 71 to 100% and were grouped in genotype B. Exceptionally, BF1676-56 isolate was closely related to Chlamydia avium with 99% identification of the 16S ribosomal (r) RNA gene.@*CONCLUSIONS@#This is the first report on C. psittaci isolated from asymptomatic feral pigeons in Thailand, which provides knowledge for the disease status in pigeon populations in Thailand.

Detection and characterization ofChlamydophila psittaci in asymptomatic feral pigeons (Columba livia domestica) in central Thailand

Objective:To detect and characterizeChlamydophila psittaci(C. psittaci) in asymptomatic feral pigeons in centralThailand.Methods:A total814 swabs from the trachea and cloacae of407 non-clinical feral pigeons in centralThailand were collected and tested for the presence ofC. psittaci.Results:A10.8% of feral pigeons in the sample group were positive as determined by nestedPCR primer specific toC. psittaci.The outer membrane proteinA(ompA) gene of positive samples exhibited amino acid identity ofC. psittaci ranging from71 to100% and were grouped in genotypeB.Exceptionally,BF1676-56 isolate was closely related toChlamydia avium with 99% identification of the16S ribosomal(r)RNA gene.Conclusions:This is the first report onC. psittaci isolated from asymptomatic feral pigeons inThailand, which provides knowledge for the disease status in pigeon populations inThailand.

Detection and characterization of chlamydophila psittaci in asymptomatic feral pigeons (Columba livia domestica) in central Thailand

Objective: To detect and characterize Chlamydophila psittaci (C. psittaci) in asymptomatic feral pigeons in central Thailand. Methods: A total 814 swabs from the trachea and cloacae of 407 non-clinical feral pigeons in central Thailand were collected and tested for the presence of C. psittaci. Results: A 10.8% of feral pigeons in the sample group were positive as determined by nested PCR primer specific to C. psittaci. The outer membrane protein A (ompA) gene of positive samples exhibited amino acid identity of C. psittaci ranging from 71 to 100% and were grouped in genotype B. Exceptionally, BF1676-56 isolate was closely related to Chlamydia avium with 99% identification of the 16S ribosomal (r) RNA gene. Conclusions: This is the first report on C. psittaci isolated from asymptomatic feral pigeons in Thailand, which provides knowledge for the disease status in pigeon populations in Thailand.

Detection of the ompA gene of Chlamydophila pecorum in captive birds in Argentina / Detección del gen ompA de Chlamydophila pecorum en aves en cautiverio, en la Argentina

Bacteria belonging to the family Chlamydiaceae cause a broad spectrum of diseases in a wide range of hosts, Including humans, other mammals and birds. However, very little is known about chlamydial infections in birds in our region. In the present study, we examined 28 clinically normal birds In illegal captivity that were confiscated in the province of Córdoba, Argentina. The objective was to detect Chlamydophila spp. in cloacal swabs by genetic analysis of the ompA gene. Nested-PCR of the ompA gene identified five samples as Chlamydophila pecorum and the sequence analysis demonstrated the presence of the ompA gene of C. pecorum In these birds. On the other hand, Chlamydophila psittaci was not detected. These birds could be either asymptomatic reservoirs or subclinical carriers of C. pecorum. This is the first report of the detection of C. pecorum in Argentina.

Las bacterias que pertenecen a la familia Chlamydiaceae causan un extenso espectro de enfermedades en una amplia gama de huéspedes, incluidos los seres humanos, otros mamíferos y aves. Sin embargo, se sabe muy poco acerca de las infecciones por clamidias en aves de nuestra reglón. Esta Investigación examinó 28 aves clínicamente normales mantenidas en cautiverio ¡legal, que fueron confiscadas en Córdoba, Argentina. El objetivo fue detectar Chlamydophila spp. en hisopados cloacales por análisis del gen ompA. La PCR anidada del gen ompA reveló la presencia de Chlamydophila pecorum en cinco muestras. El análisis de secuencias demostró la presencia del gen ompA de C. pecorum en estas aves. Por el contrario, Chlamydophila psittaci no se detectó. Estas aves pueden ser reservónos asintomáticos o portadores subclínlcos de C. pecorum. Este es el primer informe de la detección de C. pecorum en la Argentina.

Clinico-pathological Features of Chlamydophila psittaci Infection in Parrots and Genetic Characterization of the Isolates / 대한수의학회지

Avian chlamydiosis is caused by Chlamydophila psittaci and considered as one of an important zoonotic disease throughout the world. Among more than 400 avian species including poultry and pet birds susceptible to the disease, psittacine birds were known to be mostly susceptible hosts. In Korea, no outbreak of the disease and genetic analysis of the agent in poultry and pet birds have been reported. With histopathological findings and genetic identification of a causative agent, avian chlamydiosis was identified in parrots submitted from the same pet bird farm in 2006 and 2009 for the diagnosis. Based on genetic sequences and phylogenetic analysis of ompA gene, the two isolates of Chlamydophila psittaci showed 100% of genetic similarity and belonged to genotype A, suggesting that the same agent might be continuously circulated in the farm. This result indicates that serological survey of the disease in pet bird farms and impact of the disease on significance in public health may be further studied.

Generation of spaO-ompA fusion gene of Salmonella paratyphi A and the immunoprotection of expression product of the fusion gene / 中华微生物学和免疫学杂志

Objective To generate the spaO-ompA fusion gene of Salmonella paratyphi A and its prokaryotic expression system,and to determine the immunoprotection of the recombinant expression product rSpaO-OmpA.Methods A flexible peptide sequence was used to link spaO and ompA genes and a prokaryotic expression system of spaO-ompA fusion gene was subsequently generated.SDS-PAGE and Bio-Rad Agarose Image Analyzer were applied to examine the expression as well as the yield of the target recombinant protein rSpaO-OmpA.The antigenicity and immunoreactivity of rSpaO-OmpA were determined using immunodiffusion test,Western Blot assay and micro-Widal's test.By a mouse infection model,the immunoprotection of rSpaO-OmpA against the lethal challenge of S.paratyphi A was determined.In the animal protective test,the recombinant expressed SpaO (rSpaO) and OmpA ( rOmpA ) were used as the controls.Results The generated spaO-ompA fusion gene had 100％ nucleotide and amino acid sequence identities compared to the single spaO or ompA gene.The constructed prokaryotic expression system IPTG E.coli BL21DE3pET42a-spaO-ompA expressed the recombinant protein rSpaO-OmpA.rSpaO-OmpA combined with the antiserum against wholecell of S.paratyphi A to present positive hybridization signal and induced specific antibody in the immunized rabbits.Immunization with 100 or 200 μg rSpaO-OmpA contributed 66.7％ (8/12) or 83.3％ (10/12) immunoprotective rates in mice when the animals were attacked with S.paratyphi A.The immunoprotective rates produced by rSpaO-OmpA were significantly higher than that of equal rSpaO or rOmpA( P＜0.05 ).The sera from rSpaO-OmpA immunized mice presented 1∶5-1∶40 agglutination titers to the H antigens of different S.paratyphi species,and 1∶1-1∶16 immunodiffusion titers to rSpaO,rOmpA and rSpaO-OmpA proteins,respectively.Conclusion The artificially fusion antigen,rSpaO-OmpA,has more powerful immunogenicity and immunoprotection that the equal rSpaO or rOmpA.

Distribution of Salmonella paratyphi A ompA gene and immunological identification of the recombinant expressed product / 中华微生物学和免疫学杂志

Objective To construct a prokaryotic expression vector of Salmonella paratyphi A ompA gene, and to determine immunogenieity and immonuprotection of the recombinant expressed product rOmpA and carrying frequency of ompA gene in S. paratyphi A isolates. Methods ompA gene was amplified from a clinical S. paratyphi A strain JH01 by PCR, cloned into T-A cloning vector, and then the prokaryotic expression vector was constructed. The rOmpA expression was determined by SDS-PAGE. Antigenicity and immunoreactivity of rOmpA were determined by immunodiffusion test, Micro-Widal's test and Western blot assay, ompA gene exiting in 98 S. paratyphi A isolates was detected by PCR. By using immunoprotective effect of rOmpA against the challenge of S. paratyphi A strain 50001 in mice were determinded. Results Both the nucleotide and putative amino acid sequence identities of the cloned ompA gene were 100% com-pared to the reported corresponding sequences. The expression yield of rOmpA was approximately 65% of the total bacterial proteins, rOmpA was able to induce specific antibody in rabbits, and reacted efficiently with rabbit antisortm or the antiserum against whole cell of S. paratyphi A detected by Western blot. 94.9% (93/98) of the S. paratyphi A isolates had ompA gene. 41.7% (5/12) and 58.3% (7/12) of the mice im-murtized with 100 and 200 μg rOmpA were survival after lethal challenge with S. paratyphi A strain 50001. The titer of antibody to the H antigens of S. paratyphi spp in the sera from rOmpA immunized mice and sur-viral mice in the S. paratyphi A challenge detected by Micro-Widal's test was 1:5-1:40. Conclusion ompA gene has an extensive distribution in clinical isolates of S. paratyphi A. rOmpA possesses an immunogenicity and a certain immunoprotective effect, and can be used as the candidate antigen in genetic engineering vaccine.

Cloning and prokaryotic expression of the ompA gene of Chlamydia psittaci in cows / 中国人兽共患病学报

The ompA gene of Chlamyia psittaci in cows was amplified by PCR with primers designed based on those reported in GenBank.The amplified ompA gene was inserted into the bacterial plasmid vector pGEX-4T-1 and then transformed into E.coli BL21(DE3) with IPTG induction. The gene was derived from plasmid pMD18-T vector and then sequenced.It was demonstrated that this recombinant fusion protein of approximately 68kD in molecular mass was highly expressed in inclusion body and more pure proteins would be produced after purification.The fusion protein specifically reacted with positive sera of bovine Chlamydia as demonstrated by Western blotting. These results indicate that this recombinant fusion protein shows good reactivity and could be used to develop the diagnostic kit for bovine Chlamydia and genetic engineering vaccine.

Evidence of zoonotic Chlamydophila psittaci transmission in a population at risk in Zulia state, Venezuela / Evidencia de transmisión zoonótica de Chlamydophila psittacci en una población de riesgo del Estado Zulia, Venezuela

Objective This study was aimed at investigating the frequency of infection by Cp. psittaci and determining its genotype in individuals at potential risk of exposure to the bacteria. Methodology The study involved 170 individuals: a risk group (n= 96) and a low-risk control group (n=74). Cp. psittaci was detected and genotyped by single-tube nested PCR and ompA gene sequencing. Results Eight (8.3 %) positive cases were detected in the risk group and 1 (1.4 %) in the control group (p<0.04). Cp. psittaci was found in 16.7 % of pigeons' fecal samples. Cp. psittaci infection with was more frequent in symptomatic (17.7 %) than asymptomatic (6.3 %) individuals in the risk group. Analysing the genomes isolated from human and bird specimens revealed the presence of genotype B. Conclusion The presence of Cp. psittaci genotype B in the population being evaluated could have been attributed to zoonotic transmission from pigeons to humans, an underestimated potential public health problem in Venezuela requiring the health authorities' involvement.

Objetivo El objetivo de este estudio fue investigar la frecuencia de infecciones por Cp. psittaci y determinar su genotipo en individuos con potencial riesgo de exposición a la bacteria. Metodología Se incluyeron 170 individuos, un grupo de riesgo (n=96) y un grupo control (n=74). La detección y genotipificación de Cp. psittaci se llevó a cabo por PCR anidada y secuenciación del gen ompA. Resultados Se detectaron ocho (8,3 %) casos positivos en el grupo de riesgo y 1 (1,35 %) en el grupo control (p<0,04). Cp. psittaci fue detectada en 16,7 % muestras fecales de palomas. En el grupo de riesgo, la frecuencia de infección por Cp. psittaci fue 17,7 % en individuos sintomáticos y 6,3% en asintomáticos. El análisis de los genomas aislados de muestras humanas y aves, revelaron la presencia del genotipo B. Conclusión La presencia de Cp. psittaci genotipo B en la población evaluada podría ser atribuida a transmisión zoonótica de palomas a humanos, un potencial problema de salud pública en nuestra región que requiere la intervención de autoridades sanitarias.

Analysis of Leptospira interrogans ompA gene and immunological identification of its recombinant expression product / 中华微生物学和免疫学杂志

Objective To investigate the distribution of ompA gnne in 15 Chinese reference standard strains belonging to 15 serogroups of Leptospira interrogate, and to express recombinant OmpA ( rOmpA ) and to identify immunogenicity and immunoprotection of rOmpA. Methods Genomic DNAs from different leptospiral strains were extracted by phenol-chloroform method. Entire ompA gene fragments from the strains were amplified by PCR and then sequenced after T-A cloning. A prokaryotic expression system of ompA gene from L. interrogans strain 56601 was constructed, and the expression and yield of rOmpA were determined by SOS-PAGE plus Bio-Rad Agarose Image Analyser. Rabbits were immunized with rOmpA for obtaining antiserum, and immunodiffusion test was used to measure the antiserum's titer. Western blot assay was performed to determine the immunoreaetivity of rOmpA with the antiserum against rOmpA and antiserum against whole cell of L. interrogans strain 56601, while mi-croscopic agglutination test (MAT) was applied to detect the cross agglutination to the 15 L. interrogans strains. A leptospire adhering cell model and a leptospire infecting guinea pigs model were used to determine the adhesion-bloc-king effect of rOmpA antiserum and immunoprotection of rOmpA. Results All the 15 L. interrogans strains, but not L. biflexa strain Patoe Ⅰ , had sequence conserved ompA genes. The yield of rOmpA was approximate 20% of the total bacterial proteins, rOmpA could induce rabbits to produce antibody and immunodiffusion titer of the anti-serum was 1:4. Both antisera against rOmpA and against whole cell of L. interrogans strain 56601 were able to pro-duce positive Western blot signs to rOmpA, and the former offered 1 : 20-1 : 320 MAT titers to the 15 L. interrogans strains. 1: 10-1:160 dilutions of rOmpA antiserum could efficiently block L. interrogans strain 56601 adhering to J774A. 1 cells, and 100 μg and 200 μg rOmpA displayed 50.0% and 75.0% immunoprotective rates in the infee-ted guinea pigs. Conclusion ompA gene only exists in genomes of different pathogenic L. interrogans serogroups. rOmpA has relatively stronger antigenicity, cross immunoreactivity and certain immunoprotection, implying that this recombinant protein may be used as a candidate antigen for developing universal genetic engineering vaccine of L. interrogans.