RESUMEN
Coxiella (C.) burnetii, a zoonotic bacterium, is prevalent in dairy farms. Some cows develop a persistent infection and shed C. burnetii into milk and occasionally by amniotic fluid at calving. Serological diagnosis of Q fever in humans is performed by phase (Ph)-specific antibody tests; PhII antibodies usually indicate an acute infection, while the development of a chronic infection is characterised by elevated PhI antibody titres. Phase-specific tests have now been established for diagnosis of coxiellosis in cattle. Additionally, an interferon-γ (IFN-γ) recall assay has been implemented to assess cellular immunity to C. burnetii in cattle. Milk samples from all lactating cows (n = 2718) of 49 Bavarian dairy farms were collected through a convenience sample and analysed for phase-specific antibodies. Antibody profiles were evaluated by age. Based on the seropositivity of first-lactation cows, three distinct herd profiles were observed: an 'acute' state of herd infection was characterised by a PhI-/PhII+ pattern. The detection of PhI antibodies (PhI+/PhII+) characterised the 'chronic' state, and seronegative results defined the 'silent' state of herd infection. If antibodies had not been detected in multiparous cows, the herd was considered as probably free of coxiellosis. The analysed cattle herds were noted to have an 'acute' (n = 12, 24.5%), 'chronic' (n = 18, 36.8%), or 'silent' state of herd infection (n = 16, 32.6%). Only three farms (6.1%) were classified as 'free' of C. burnetii. The detection of these herd states over a time period of 4 years in one farm indicated that the described states occur in a cyclical manner. Frequently, a wave-like profile was seen, i.e., a circumscribed seronegative age group was flanked by seropositive age groups. In seronegative animals, IFN-γ reactivity was demonstrated. Seroconversion after vaccination was observed by day 7 post-vaccination in chronically infected herds, whereas in the case of silent infection, it started by day 14. These data indicated a pre-existing immunity in seronegative animals in chronically infected herds. Additionally, IFN-γ reactivity was detected in seronegative calves (>3 months) and heifers from chronically infected farms compared to a negative farm. An infection prior to 3 months of age resulted in cellular immunity in the absence of detectable antibodies. An infection around calving would explain this. The aforementioned circumscribed seronegative age groups are, therefore, explained by an infection early in life during active shedding at calving. Based on these results, an endemic cycle of coxiellosis is proposed: Susceptible young heifers get infected by persistently infected cows. Subsequently, shedding of C. burnetii at calving results in infection and then in cellular immunity in offspring. When these calves enter the cow herd two years later, a maximum of herd immunity is achieved, shedding ceases, and new susceptible animals are raised. In an acutely infected dairy farm, the PhI+/PhII+ serological pattern prevailed in second-lactation cows. In this study, stored sera collected since birth were analysed retrospectively. From the earliest seroconversion, the peak of seroconversion took about 33 months. These data suggested a slow spread of infection within herds. The classification of dairy cow herds is a promising basis for further analysis of the clinical impact of coxiellosis.
RESUMEN
Q fever in humans is caused by Coxiella (C.) burnetii. In 2008 and 2012, cases of Q fever in humans were linked to an infected flock of approximately 650 ewes. Since 2013 gimmers (G'13, G'14, G'15 etc.) were primary vaccinated (two doses) with an inactivated C.burnetii vaccine without any revaccination. In 2013, 30 ewes were primary vaccinated (A'13). Shedding was annually monitored by qPCR-testing of vaginal and nasal swabs collected at lambing. Animals were tested for Phase I- (PhI) and PhII-antibodies (Ab) and for PhII-specific-interferon-γ (IFN-γ) before and after vaccination. The effect of a revaccination was determined in 2018 and 2023. Groups of randomly selected gimmers primary vaccinated in 2015, 2016 and 2017 and a mixed group of older animals (A'13, G'13 and G'14) were revaccinated once in 2018. The trial was repeated in 2023 on groups primary vaccinated in 2019-2023. Major shedding after the outbreak in 2012 ceased in 2014. Thereafter C.burnetii was only sporadically detected at low-level in 2018, 2021 and 2023. Sheep naturally exposed to C.burnetii during the outbreak in 2012 (A'13, G'13) mounted a strong and complete (PhI, PhII, IFN-γ) recall immune response after vaccination. A serological PhI+/PhII+ pattern dominated after vaccination. In contrast, since 2014 a weaker immune response (PhII-titre, IFN-γ) and a dominance of the PhI-/PhII+ pattern was observed in vaccinated gimmers. The number of serologically non-responding gimmers to vaccination increased to 25.0 % in G'16/G'17 and 40.4 % in G'19/G'20. But revaccination even three (G'15 in 2018) and four (G'19 in 2023) years after primary vaccination resulted in a strong and complete immune response. No difference of the immune response nor to more recently primary vaccinated animals (G'23 in 2023) nor to those animals that were present during the outbreak (A'13/G'13/G'14 in 2018) was observed.
Asunto(s)
Coxiella burnetii , Fiebre Q , Humanos , Ovinos , Animales , Femenino , Fiebre Q/prevención & control , Fiebre Q/veterinaria , Fiebre Q/epidemiología , Anticuerpos , Vacunas Bacterianas , InmunidadRESUMEN
Coxiella (C.) burnetii, a Gram-negative intracellular bacterium, causes Q fever in humans and Coxiellosis in animals. Ruminants are a primary source of human infection with C.burnetii. In 2013, vaccination was implemented in a sheep flock with 650 ewes associated with two outbreaks of Q fever in humans in 2008 and 2012. Only gimmers (yearlings) received two doses of a commercial C.burnetii phase I whole cell vaccine three weeks apart (primary vaccination) without any revaccination. Vaginal and nasal swabs collected shortly after lambing were tested by qPCR. Additionally, a group of non-vaccinated sentinels was serologically monitored for phase I (PhI), II (PhII) antibodies and for Interferon γ (IFN-γ) after stimulation of whole blood cells with PhII-antigen with and without an IL-10-neutralizing monoclonal antibody. In 2021, 679 sera collected in 2014-2021 were retested retrospectively with three commercial ELISA kits and one batch of an in-house PhI/PhII-ELISA. A low-level shedding of C.burnetii (<103 mean C.burnetii/swab) was observed until 2014. In 2021 C.burnetii was detected in two animals (<103.1C.burnetii/swab), but vaginal swabs collected at two subsequent lambing seasons remained negative. Seroconversion of sentinels was detected until 2017. However, the retrospective analysis of sentinels in 2021 revealed additional single seropositive animals from 2018 to 2021. IFN-γ reactivity was observed during the whole study period; it peaked in 2014 and in 2018 and decreased thereafter. The sporadic detection of C.burnetii and the immune responses of sentinels suggested that a subliminal infection persisted despite vaccination. Nevertheless, vaccination of gimmers prevented the development of a major outbreak, it controlled the infection and reduced the risk of human infection.
Asunto(s)
Coxiella burnetii , Fiebre Q , Enfermedades de las Ovejas , Animales , Femenino , Humanos , Fiebre Q/epidemiología , Fiebre Q/prevención & control , Fiebre Q/veterinaria , Estudios Retrospectivos , Ovinos , Enfermedades de las Ovejas/epidemiología , Enfermedades de las Ovejas/microbiología , Enfermedades de las Ovejas/prevención & control , Vacunación/veterinariaRESUMEN
Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) appears in two genotypes (EU and US), for both genotypes attenuated live-vaccines are available. A cross-sectional study in 38 Bavarian sow herds was performed to assess the level of neutralizing antibodies. Per herd 38 blood samples were collected (10 weaned piglets, 10 gilts and 6 sows of 1./2., 3J4. and 5/6. parity, respectively). Sera were tested by ELISA, serumneutralization test (SNT) against EU- and US-vaccine virus, and pooled sera were tested by real-time RT-PCR. Herds were classified by the last vaccination of sows as "Vacc EU" "Vacc US"and "nv (non-vaccinated) and by detection of PRRSV-US and vaccination of piglets were not included as variables. Sows of group (2) Vacc EU/EU- showed the highest EU-SNT-titers irrespective of parity. Groups (5) Vacc US/EU+ and (1) Vacc EU/EU+ followed in descending order. Significantly lower SNT-titers in (1) Vacc EU/EU+ were especially observed in sows of 1/2. Parity (Kruskal-Wallis, p < 0.05). Very low SNT-titers were observed in the three remaining groups (3) nv/EU+, (4) nv/EU- and (6) Vacc US/EU-. In US-vaccinated herds detection of PRRSV-EU coincided with strong ELISA-reactivity in all animal groups. In EU-vaccinated herds this was only observed for weaned piglets. Sows showed a strong ELISA-reactivity irrespective of detection of PRRSV-EU. The value of the ELISA is restricted to the certification of PRRSV-free herds. The EU-SNT reflects the level of herd immunity at least against vaccine virus; it indicates gaps in herd immunity.
Asunto(s)
Anticuerpos Antivirales/sangre , Inmunidad Colectiva , Pruebas de Neutralización/veterinaria , Síndrome Respiratorio y de la Reproducción Porcina/inmunología , Virus del Síndrome Respiratorio y Reproductivo Porcino/inmunología , Vacunas Virales/inmunología , Animales , Anticuerpos Neutralizantes/sangre , Estudios Transversales , Ensayo de Inmunoadsorción Enzimática/veterinaria , Unión Europea , Femenino , Genotipo , Alemania , Masculino , Síndrome Respiratorio y de la Reproducción Porcina/prevención & control , Virus del Síndrome Respiratorio y Reproductivo Porcino/clasificación , Virus del Síndrome Respiratorio y Reproductivo Porcino/genética , Porcinos , Vacunas Atenuadas/inmunologíaRESUMEN
The causative agent of Q fever, Coxiella burnetii, is a query agent occurring naturally all over the world. We studied 104 German Coxiella burnetii strains/DNA samples obtained between 1969 and 2011 using a 14 microsatellite marker Multiple-locus variable-number of tandem repeat (VNTR) analysis (MLVA) technique. We were able to divide our collection into 32 different genotypes clustered into four major groups (A-D). Two of these (A and C) formed predominant clonal complexes that covered 97% of all studied samples. Group C consisted exclusively of cattle-associated isolates/DNA specimens, while group A comprised all other affected species including all sheep-derived strains/DNA samples. Within this second cluster, two major genotypes (A1, A2) were identified. Genotype A2 occurred in strains isolated from ewes in northern and central Germany, whereas genotype A1 was found in most areas of Germany. MLVA analysis of C. burnetii strains from neighbouring countries revealed a close relationship to German strains. We thus hypothesize that there is a western and central European cluster of C. burnetii. We identified predominant genotypes related to relevant host species and geographic regions which is in line with findings of the Dutch Q fever outbreak (2007-2010). Furthermore three of our analyzed German strains are closely related to the Dutch outbreak clone. These findings support the theory of predominant genotypes in the context of regional outbreaks. Our results show that a combination of 8 MLVA markers provides the highest discriminatory power for attributing C. burnetii isolates to genotypes. For future epidemiological studies we propose the use of three MLVA markers for easy and rapid classification of C. burnetii into 4 main clusters.
Asunto(s)
Coxiella burnetii/clasificación , Coxiella burnetii/genética , Variación Genética , Tipificación Molecular , Fiebre Q/microbiología , Fiebre Q/veterinaria , Animales , Bovinos , Coxiella burnetii/aislamiento & purificación , Genotipo , Alemania , Humanos , Repeticiones de Minisatélite , Filogeografía , OvinosRESUMEN
C. burnetii infection might be associated with puerperal shedding; additionally, the chronic shedding of this pathogen in milk has been observed in individual animals. A longitudinal survey was performed in an endemically infected dairy cow herd with 100 cows in order to compare phase-specific milk-serology with pathogen shedding. From March 2010 through December 2011, 870 individual milk samples from 212 cows were analysed using both quantitative (q) PCR and phase-specific antibody-ELISA. The mean milk-shedding/cow was calculated for 137 cows with > or = 3 milk samples per cow. In addition, 110 puerperal swabs were collected after August 2010. The cows yielding three successive qPCR-positive milk samples or > 3 qPCR-positive milk samples, irrespective of the sequence of positive/negative results, were classified as chronic shedders (CS). Milk shedding was observed during the entire study, but a major period of puerperal shedding occurred from February through October 2011; 35/52 swabs tested positive, whereas only 3/58 swabs collected outside this period were positive. The PhI/PhII(+)-pattern in primiparous cows (< 36 months old) was consistent with puerperal shedding in the herd, but not at the individual level. This pattern was observed in older cows, irrespective of the period of puerperal shedding. Four primiparous CS-cows showed low-level mean shedding < 100 C.b./ml milk, and the PhI-titre increased from negative or weakly positive to more than 500 at the end of the first lactation. Puerperal shedding during the second parturition was observed in three of these cows. Six multiparous CS-cows with mean shedding exceeding 100 C.b./ml milk were characterised with stable PhI-titres of > or = 500. The three available puerperal swabs tested negative. Only one multiparous CS-cow showed low-level shedding and a PhI-titre below 500 for the entire study. In conclusion, the PhI-/PhII(+)-pattern in primiparous cows indicated puerperal shedding at the herd level, and a PhI-titre > or = 500 is a suitable screening method for the detection of chronic shedding in milk.
Asunto(s)
Derrame de Bacterias , Enfermedades de los Bovinos/microbiología , Coxiella burnetii/aislamiento & purificación , Leche/microbiología , Infección Puerperal/veterinaria , Fiebre Q/veterinaria , Animales , Bovinos , Enfermedades de los Bovinos/diagnóstico , Enfermedad Crónica , Coxiella burnetii/genética , Coxiella burnetii/inmunología , Ensayo de Inmunoadsorción Enzimática/veterinaria , Femenino , Estudios Longitudinales , Infección Puerperal/diagnóstico , Infección Puerperal/microbiología , Fiebre Q/diagnóstico , Fiebre Q/microbiología , Reacción en Cadena en Tiempo Real de la Polimerasa/veterinariaRESUMEN
Avian adenovirus infections cause important disease complexes in chickens, but many of the viruses also infect chickens without resulting in overt disease. Previously several outbreaks of gizzard erosions caused by a fowl adenovirus A serotype-1 (FAdV-1) were reported from Japan. Here we report an outbreak of gizzard erosions in 12 broiler flocks in Germany in 2011. Chickens had a reduced daily weight gain and a higher total mortality rate of up to 8%. The birds showed a severe detachment of the koilin layer and ulcerative to necrotizing lesions of the underlying mucosa. Histopathologically, necrotizing ventriculitis with basophilic, intranuclear inclusion bodies in epithelial cells was diagnosed. Immunohistochemistry, egg culture, and electron microscopic examination revealed adenovirus-like particles in the samples. No concurrent infectious agent could be identified. The virus was genotyped as FAdV-1 by PCR and subsequent sequencing. Phylogenetic analysis of the hexon loop L1 gene yielded 100% sequence identity to the chicken embryo lethal orphan strain. These findings suggest that outbreaks of adenoviral gizzard erosion can lead to significant economic losses in Germany and may be caused by an unusual virulent FAdV-1 strain.
Asunto(s)
Pollos , Brotes de Enfermedades/veterinaria , Adenovirus A Aviar/aislamiento & purificación , Molleja de las Aves/patología , Enfermedades de las Aves de Corral/epidemiología , Enfermedades de las Aves de Corral/virología , Gastropatías/veterinaria , Animales , Proteínas de la Cápside/genética , Proteínas de la Cápside/metabolismo , Adenovirus A Aviar/genética , Técnicas de Genotipaje/veterinaria , Alemania/epidemiología , Molleja de las Aves/ultraestructura , Microscopía Electrónica de Transmisión/veterinaria , Filogenia , Reacción en Cadena de la Polimerasa/veterinaria , Enfermedades de las Aves de Corral/patología , Análisis de Secuencia de ADN/veterinaria , Gastropatías/epidemiología , Gastropatías/patología , Gastropatías/virología , Aumento de PesoRESUMEN
A voluntary marker-independent Bovine Herpesvirus 1 (BoHV1) eradication program started in 1986; in 1998 it changed to a compulsory one. Certification of free regions in European member states is based on Article 10 of directive 64/432/EEC. According to this rule Bavaria is listed as free of BoHV1 since October 2011. Surveillance of BoHV1-free dairy cattle farms is currently performed with quarterly bulk-milk testing. Non-negative bulk-milk results must be confirmed by blood tests in cattle older than nine months. An increased regional rate of non-negative bulk-milk samples and the subsequent detection of epidemiologically non-feasible singleton BoHV1-reactors by analysis of blood were observed at the final stage of eradication in southwest Bavaria. Nineteen case farms (734 animals) defined by singleton reactors born at least two years after certification of the farms as BoHV1-free, 23 negative control (NC) farms (NC I: 321 animals) from the same region, 11 NC-farms (NC II: 423 animals) from an already-certified Article 10 region in northeast Bavaria and two BoHV1-infected farms (264 animals) were analysed using BoHV1-, BoHV2- and Feline Herpesvirus 1 (FeHV1)-neutralisation tests (NTs), and three commercially available ELISAs supplied by Idexx Laboratories, B.V., The Netherlands: the CHEKIT™ Trachitest 2nd Gen. test for milk or serum (Trachitest), Herdchek™ gB- (gB-ELISA) and Herdchek™ gE-ELISA (gE-ELISA). Significantly increased levels of BoHV2 antibodies were observed on case farms compared to NC I or II farms. Additionally, reactivity by gB-ELISA and the Trachitest was significantly increased for animals with BoHV2 neutralising antibodies. Singleton BoHV1-reactors tested negative by gE-ELISA even if an elevated cut-off of 0.95±0.05 was applied. At this cut-off, the gE-ELISA was as sensitive and specific as the gB-ELISA. Comparative titration of milk samples from seropositive animals from a BoHV1-infected dairy cattle farm and from singleton BoHV1-reactors performed in CHEKIT™ Trachitest 2nd Gen. Milk revealed that the slopes of both groups were distinct; therefore, optimised cut-offs for bulk-milk testing to exclude singleton BoHV1-reactors are proposed.
Asunto(s)
Anticuerpos Antivirales/análisis , Herpesvirus Bovino 1 , Leche/virología , Animales , Anticuerpos Antivirales/sangre , Bovinos , Enfermedades de los Bovinos/inmunología , Enfermedades de los Bovinos/prevención & control , Enfermedades de los Bovinos/virología , Reacciones Cruzadas , Erradicación de la Enfermedad , Ensayo de Inmunoadsorción Enzimática/métodos , Ensayo de Inmunoadsorción Enzimática/veterinaria , Europa (Continente) , Infecciones por Herpesviridae/inmunología , Infecciones por Herpesviridae/prevención & control , Infecciones por Herpesviridae/veterinaria , Infecciones por Herpesviridae/virología , Leche/químicaRESUMEN
Serological diagnosis of acute and chronic Q fever in humans relies on detection of antibodies to phase I (PhI) and II (PhII) antigens of Coxiella (C.) burnetii. Although phase-specific antigens are available, they are not yet used in ruminants as they are in humans. This study focuses on phase-specific serology as a tool for analysis of the dynamics of infection in cattle. As a prerequisite, sero-prevalence in Bavarian cattle (1) and sero-prevalences for age-groups (2) were determined by ELISA (CHEKIT Q-Fever; mix of PhI/PhII-antigen). Subsequently, phase-specific antigens were coated onto ELISA plates individually and tests were simultaneously applied in an endemically infected herd with about 90 dairy cows and 250 calves/heifers in April 2005, March 2006 and retrospectively in May and October 2004. From April 2005 onward, placentas were analysed for C. burnetii by PCR (3). (1) Sero- and herd prevalences based on 21,051 sera from 603 Bavarian dairy farms collected in 2003 were 14.8% ± 0.48% and 72.3% ± 3.6%, respectively. (2) Analysis of 3965 animals from 105 farms for which age was reported revealed a base level of sero-prevalence of less than 5% in 1-2 years old animals, it increased to 15% in 2-3 years old and reached a plateau (25-30%) in cows four years and older. (3) In May 2004 and April 2005 a peak of PhI(-)/PhII(+)-prevalence in primiparous cows (2.0-3.5 years) was observed; but not in October 2004 and March 2006. The PhI(-)/PhII(+)-pattern in primiparous cows changed to negative (one-third), PhI(+)/PhII(+) (1/3) or persisted (1/3). In contrast, sero-conversion was rare in multiparous cows (>3.5 years). If the PhI(-)/PhII(+) pattern was detected, it was due to an infection in preceding years. This pattern persisted (2/3) or changed to negative (1/3); a change to PhI(+)/PhII(+) did not occur. PhI(-)/PhII(+) in heifers (1-2 years) always changed to negative. Detection of PhII-antibodies was significantly associated with PCR-positive placentas. Remarkably, 45% of sera with the PhI(-)/PhII(+) pattern were negative for the CHEKIT Q-Fever ELISA, thus this test missed an important group of infected animals.
Asunto(s)
Anticuerpos Antibacterianos/sangre , Enfermedades de los Bovinos/microbiología , Bovinos/microbiología , Coxiella burnetii/aislamiento & purificación , Fiebre Q/veterinaria , Animales , Enfermedades de los Bovinos/epidemiología , Coxiella burnetii/genética , Coxiella burnetii/inmunología , Ensayo de Inmunoadsorción Enzimática , Femenino , Alemania/epidemiología , Placenta/microbiología , Reacción en Cadena de la Polimerasa , Embarazo , Complicaciones Infecciosas del Embarazo , Prevalencia , Fiebre Q/epidemiología , Fiebre Q/inmunología , Estudios Seroepidemiológicos , Factores de TiempoRESUMEN
Since 2007 a new fatal haemorrhagic diathesis in calves has been observed in all areas of Germany. Analysis of 56 cases submitted for necropsy allowed its characterization. Calves fell ill within the first month of life independent of breed and sex. Only single or a few animals per herd were affected. Petechial and ecchymotic haemorrhages in many organs and tissues, particularly in skin, subcutis and gastrointestinal tract, were major findings in all animals. Microscopically a severe depletion of bone marrow cells was always observed. Lymphocytic depletion (43%) and inflammatory lesions (46%) were less frequently observed. Blood analysis of five animals indicated an aplastic pancytopenia. The resulting thrombocytopenia is regarded as major pathomechanism of this Haemorrhagic Disease Syndrome (HDS). Pedigree analysis gave no indication of hereditary disease. Tests for specific toxins such as S-(1,2-Dichlorovinyl)-L-cysteine (DCVC), furazolidone, or mycotoxins resulting in bone marrow depletion were negative. Bacterial infections, Bovine Viral Diarrhoea Virus, and Bluetongue Virus were ruled out as cause of the disease. HDS shares similarities with a circoviral infection in chickens (chicken infectious anaemia). A broad-spectrum PCR allowed detection of circoviral DNA in 5 of 25 HDS cases and in 1 of 8 non-HDS cases submitted for necropsy. Sequencing of the whole viral genome revealed a high similarity (up to 99%) with Porcine Circovirus type 2b. Single bone marrow cells stained weakly positive for PCV2 antigen by immunohistochemistry in 1 of 8 tested HDS animals. This is the first report of circovirus detection in cattle in Germany. The exact cause of HDS still remains unknown. A multifactorial aetiology involving infection, poisoning, immunopathy, or a genetic predisposition is conceivable. Additional research is necessary to clarify the pathogenesis and the potential role of PCV2 in HDS.
Asunto(s)
Diarrea Mucosa Bovina Viral/epidemiología , Enfermedades de los Bovinos/epidemiología , Animales , Autopsia/veterinaria , Diarrea Mucosa Bovina Viral/inmunología , Diarrea Mucosa Bovina Viral/patología , Bovinos , ADN Viral/genética , ADN Viral/aislamiento & purificación , Virus de la Diarrea Viral Bovina Tipo 2/clasificación , Virus de la Diarrea Viral Bovina Tipo 2/genética , Virus de la Diarrea Viral Bovina Tipo 2/aislamiento & purificación , Virus de la Diarrea Viral Bovina/genética , Virus de la Diarrea Viral Bovina/aislamiento & purificación , Femenino , Alemania/epidemiología , Hemorragia/epidemiología , Hemorragia/patología , Hemorragia/veterinaria , Masculino , Pancitopenia/epidemiología , Pancitopenia/veterinaria , Linaje , Filogenia , Reacción en Cadena de la PolimerasaRESUMEN
Immune responses against the protective antigen (PA) of Bacillus anthracis are known to confer immunity against anthrax. We evaluated the efficacy of genetic vaccination with plasmid vectors encoding PA, in protecting mice from a lethal challenge with B. anthracis STI spores. BALB/c and A/J mice were immunized via gene gun inoculation, using eukaryotic expression vectors with different cellular targeting signals for the encoded antigen. The vector pSecTag PA83, encoding the full-length PA protein, has a signal sequence for secretion of the expressed protein. The plasmids pCMV/ER PA83 and pCMV/ER PA63, encoding the full-length and the physiologically active form of PA, respectively, target and retain the expressed antigen in the endoplasmic reticulum of transfected cells. All three plasmids induced PA-specific humoral immune responses, predominantly IgG1 antibodies, in mice. Spleen cells collected from plasmid-vaccinated BALB/c mice produced PA-specific interleukin-4, interleukin-5, and interferon-gamma in vitro. Vaccination with either pSecTag PA83 or pCMV/ER PA83 showed significant protection of A/J mice against infection with B. anthracis STI spores.