Novel phage display-derived recombinant antibodies recognizing both MPT64 native and mutant (63-bp deletion) are promising tools for tuberculosis diagnosis.

Tuberculosis (TB) is one of the top 10 causes of death in humans worldwide. The most important causative agents of TB are bacteria from the Mycobacterium tuberculosis complex (MTC), although nontuberculous mycobacteria (NTM) can also cause similar infections. The ability to identify and differentiate MTC isolates from NTM is important for the selection of the correct antimicrobial therapy. Immunochromatographic assays with antibodies anti-MPT64 allow differentiation between MTC and NTM since the MPT64 protein is specific from MTC. However, studies reported false-negative results mainly due to mpt64 63-bp deletion. Considering this drawback, we selected seven human antibody fragments against MPT64 by phage display and produced them as scFv-Fc. Three antibodies reacted with rMPT64 mutant (63-bp deletion) protein and native MPT64 from M. tuberculosis H37Rv in ELISA and Western blot. These antibodies are new biological tools with the potential for the development of TB diagnosis helping to overcome limitations of the MPT64-based immunochromatographic tests currently available.

Combined use of ELISA and Western blot with recombinant N protein is a powerful tool for the immunodiagnosis of avian infectious bronchitis.

BACKGROUND: The avian infectious bronchitis virus (IBV) remains a significant source of loss in the poultry industry and early diagnosis is required to prevent the disease from spreading. This study examined the combined use of an ELISA and Western blot (WB) to detect antibodies against the nucleocapsid protein (N) of IBV. The coding sequence for N was amplified by RT-PCR and expressed in Escherichia coli. A soluble recombinant N protein (rN) of approximately 50 kDa was obtained. A total of 389 sera were tested against the rN in ELISA and the results were compared with those of the commercial IDEXX IBV Ab test. ELISA-rN achieved a 90.34% sensitivity and 90.16% specificity. WB confirmed all false negative sera in ELISA-rN or IDEXX test as truly positive. The current study indicate that the combined use of rN in ELISA and WB is a powerful tool for the immunodiagnosis of avian infectious bronchitis. METHODS: Constructed recombinant pAE/n expression vectors were used to transform E. coli BL21(DE3) Star competent cells (Invitrogen). The rN of infectious bronchitis virus was purified by affinity chromatography using HisTrap HP 1 mL columns pre-packed with pre-charged Ni Sepharose in the ÄKTAprime Automated Liquid Chromatography system (GE Healthcare). A total of 389 serum samples from chickens were used to develop and evaluate the ELISA-rN test. To standardize the indirect ELISA development, serum dilutions (1:100, 1:200 and 1:400) and different concentrations of purified rN antigen (50, 100 and 200 ng/well) were tested. Positive and negative sera for IBV were used as controls. The results were compared with those obtained from a commercial kit. Serum samples scored as negative with the commercial kit but as positive with the ELISA-rN were further analysed by Western blot analyses using the rN protein as an antigen. The results of the ELISA-rN were compared to the commercial kit results using receiver-operating characteristics curves, area under the curve, and confidence intervals with the software GraphPad Prism version 6.0 for Windows (GraphPad Software, USA). RESULTS: The expected cDNA fragment of approximately 1240 bp was successfully amplified by PCR using primers designed to select for the coding region of the N protein. The rN was expressed as a soluble protein to avoid the refolding steps and, after purification a yield of 10 mg/L of rN was obtained. The SDS-PAGE results demonstrated the presence of two distinct bands that had a molecular mass of approximately 45 and 50 KDa. Out of 244 sera that scored positive in the commercial ELISA IDEXX IBV Ab Test, 220 were also positive in the ELISA-rN, yielding an ELISA-rN test sensitivity of 90.16%. Out of 145 sera that scored negative in the IDEXX IBV Ab Test, 131 also scored negative in the ELISA-rN, indicating a specificity of 90.34%. Sera that tested negative in the ELISA-rN and positive in the commercial test also reacted with the rN protein in Western blot. CONCLUSIONS: The association between the ELISA and Western blot techniques developed in this study with a subunit of IBV (rN) were able to detect antibodies that the commercial ELISA did not detect suggesting that the ELISA-rN has greater sensitivity.

Parenteral adjuvant potential of recombinant B subunit of Escherichia coli heat-labile enterotoxin.

BACKGROUND: The B subunit of Escherichia coli heat-labile enterotoxin (LTB) is a potent mucosal immune adjuvant. However, there is little information about LTB's potential as a parenteral adjuvant. OBJECTIVES: We aimed at evaluating and better understanding rLTB's potential as a parenteral adjuvant using the fused R1 repeat of Mycoplasma hyopneumoniae P97 adhesin as an antigen to characterise the humoral immune response induced by this construct and comparing it to that generated when aluminium hydroxide is used as adjuvant instead. METHODS: BALB/c mice were immunised intraperitoneally with either rLTBR1 or recombinant R1 adsorbed onto aluminium hydroxide. The levels of systemic anti-rR1 antibodies (total Ig, IgG1, IgG2a, and IgA) were assessed by enzyme-linked immunosorbent assay (ELISA). The ratio of IgG1 and IgG2a was used to characterise a Th1, Th2, or mixed Th1/Th2 immune response. FINDINGS: Western blot confirmed rR1, either alone or fused to LTB, remained antigenic; anti-cholera toxin ELISA confirmed that LTB retained its activity when expressed in a heterologous system. Mice immunised with the rLTBR1 fusion protein produced approximately twice as much anti-rR1 immunoglobulins as mice vaccinated with rR1 adsorbed onto aluminium hydroxide. Animals vaccinated with either rLTBR1 or rR1 adsorbed onto aluminium hydroxide presented a mixed Th1/Th2 immune response. We speculate this might be a result of rR1 immune modulation rather than adjuvant modulation. Mice immunised with rLTBR1 produced approximately 1.5-fold more serum IgA than animals immunised with rR1 and aluminium hydroxide. MAIN CONCLUSIONS: The results suggest that rLTB is a more powerful parenteral adjuvant than aluminium hydroxide when administered intraperitoneally as it induced higher antibody titres. Therefore, we recommend that rLTB be considered an alternative adjuvant, even if different administration routes are employed.

Novel phage display-derived recombinant antibodies recognizing both MPT64 native and mutant (63-bp deletion) are promising tools for tuberculosis diagnosis

Tuberculosis (TB) is one of the top 10 causes of death in humans worldwide. The most important causative agents of TB are bacteria from the Mycobacterium tuberculosis complex (MTC), although nontuberculous mycobacteria (NTM) can also cause similar infections. The ability to identify and differentiate MTC isolates from NTM is important for the selection of the correct antimicrobial therapy. Immunochromatographic assays with antibodies anti-MPT64 allow differentiation between MTC and NTM since the MPT64 protein is specific from MTC. However, studies reported false-negative results mainly due to mpt64 63-bp deletion. Considering this drawback, we selected seven human antibody fragments against MPT64 by phage display and produced them as scFv-Fc. Three antibodies reacted with rMPT64 mutant (63-bp deletion) protein and native MPT64 from M. tuberculosis H37Rv in ELISA and Western blot. These antibodies are new biological tools with the potential for the development of TB diagnosis helping to overcome limitations of the MPT64-based immunochromatographic tests currently available.

Protection efficacy of the rLTB-R1 chimera against experimental swine mycoplasmal pneumonia

Background: Mycoplasma hyopneumoniae is the etiological agent of the Swine Mycoplasmal Pneumonia (SMP), one of the most economically significant diseases in the swine industry worldwide. Commonly used vaccines for SMP control consist of inactivated whole cells (bacterins). These vaccines are efficacious against M. hyopneumoniae challenge, but do not prevent colonization by the pathogen or completely eliminate pneumonia. P97 adhesin is conserved in the M. pneumoniae virulent strains, therefore it is an attractive target to be used in recombinant vaccines against M. hyopneumoniae. The aim of the present study was to evaluate protection afforded by rLTB-R1, a recombinant chimera composed by LTB fused with the R1 repeat region of P97 adhesin of M. hyopneumoniae, in specific-pathogen-free (SPF) piglets vaccinated by intranasal or intramuscular route and challenged with a pathogenic strain of M. hyopneumoniae. Materials, Methods & Results: PCR products of the LTB and R1 coding sequences were fused, then cloned into pETDEST42™ expression vector. The rLTB-R1 was expressed in Escherichia coli BL21 (DE3) Salt induction (SI). The piglets were divided into three groups: four piglets were intranasally vaccinated with 1 mg of rLTB-R1 solubilized in 1 mL of PBS at 0 and 14 days (IN rLTB-R1 group); four piglets were intramuscularly vaccinated with 1 mg of rLTB-R1 solubilized in 1 mL of PBS at 0 and 14 days (IM rLTB-R1 group); three piglets were intranasally and intramuscularly inoculated with 1 mL of PBS (control group). Two weeks after the last immunization (28 day), piglets were intratracheally challenged with 10 mL of a suspension containing 109 color-changing unit (CCU) of pathogenic M. hyopneumoniae 7448 strain on three consecutive days. Until the challenge (28 days), intranasal and intramuscular vaccination with rLTB-R1 induced seroconversions of antiR1 systemic antibodies of 1.6 and 4.6 ×, respectively. The IN rLTB-R1 group had no pulmonary lesion, rLTB-R1 conferred protection against experimental SMP. On the other hand, IM rLTB-R1 and control groups had on average 7.24% and 8.46% of pulmonary lesion, respectively, showing that intramuscular vaccination with rLTB-R1 did not confer protection. Discussion: The rLTB-R1, when intranasally administrated to mice, elicited production of anti-R1 IgA in trachea and bronchi as well as specific Th1 response, suggesting an adequate stimulation of the mucosal immune system. We believe that rLTB-R1 induced a similar immune response in piglets intranasally vaccinated, conferring protection against experimental SMP. The present study, the rLTB-R1 alone, without any chemical adjuvant, stimulated a significant seroconversion of anti-R1 systemic antibodies in pigs intramuscularly vaccinated, showing the potential of LTB as a parenteral adjuvant in swine vaccination. Previous work has shown that the intramuscular administration route was evaluated in pigs because mice intramuscularly vaccinated with rLTB-R1 presented significant levels of anti-R1 IgA in trachea and bronchi, suggesting that rLTB can stimulate some degree of mucosal immunity even if not delivered by a mucosal route. However, in the present study, piglets intramuscularly vaccinated with rLTB-R1 presented high levels of anti-R1 systemic antibodies, they were not protected. On the other hand, intranasal vaccination of piglets with rLTB-R1 elicited low levels of antiR1 systemic antibodies (1.6 × at 28 days), but it conferred full protection against experimental SMP. The present study demonstrated that intranasal vaccination of piglets with rLTB-R1 conferred protection against experimental SMP. A more detailed analysis of the protective immune response induced by rLTB-R1 in pigs is currently being performed.

Protection efficacy of the rLTB-R1 chimera against experimental swine mycoplasmal pneumonia

Background: Mycoplasma hyopneumoniae is the etiological agent of the Swine Mycoplasmal Pneumonia (SMP), one of the most economically significant diseases in the swine industry worldwide. Commonly used vaccines for SMP control consist of inactivated whole cells (bacterins). These vaccines are efficacious against M. hyopneumoniae challenge, but do not prevent colonization by the pathogen or completely eliminate pneumonia. P97 adhesin is conserved in the M. pneumoniae virulent strains, therefore it is an attractive target to be used in recombinant vaccines against M. hyopneumoniae. The aim of the present study was to evaluate protection afforded by rLTB-R1, a recombinant chimera composed by LTB fused with the R1 repeat region of P97 adhesin of M. hyopneumoniae, in specific-pathogen-free (SPF) piglets vaccinated by intranasal or intramuscular route and challenged with a pathogenic strain of M. hyopneumoniae. Materials, Methods & Results: PCR products of the LTB and R1 coding sequences were fused, then cloned into pETDEST42™ expression vector. The rLTB-R1 was expressed in Escherichia coli BL21 (DE3) Salt induction (SI). The piglets were divided into three groups: four piglets were intranasally vaccinated with 1 mg of rLTB-R1 solubilized in 1 mL of PBS at 0 and 14 days (IN rLTB-R1 group); four piglets were intramuscularly vaccinated with 1 mg of rLTB-R1 solubilized in 1 mL of PBS at 0 and 14 days (IM rLTB-R1 group); three piglets were intranasally and intramuscularly inoculated with 1 mL of PBS (control group). Two weeks after the last immunization (28 day), piglets were intratracheally challenged with 10 mL of a suspension containing 109 color-changing unit (CCU) of pathogenic M. hyopneumoniae 7448 strain on three consecutive days. Until the challenge (28 days), intranasal and intramuscular vaccination with rLTB-R1 induced seroconversions of antiR1 systemic antibodies of 1.6 and 4.6 ×, respectively. The IN rLTB-R1 group had no pulmonary lesion, rLTB-R1 conferred protection against experimental SMP. On the other hand, IM rLTB-R1 and control groups had on average 7.24% and 8.46% of pulmonary lesion, respectively, showing that intramuscular vaccination with rLTB-R1 did not confer protection. Discussion: The rLTB-R1, when intranasally administrated to mice, elicited production of anti-R1 IgA in trachea and bronchi as well as specific Th1 response, suggesting an adequate stimulation of the mucosal immune system. We believe that rLTB-R1 induced a similar immune response in piglets intranasally vaccinated, conferring protection against experimental SMP. The present study, the rLTB-R1 alone, without any chemical adjuvant, stimulated a significant seroconversion of anti-R1 systemic antibodies in pigs intramuscularly vaccinated, showing the potential of LTB as a parenteral adjuvant in swine vaccination. Previous work has shown that the intramuscular administration route was evaluated in pigs because mice intramuscularly vaccinated with rLTB-R1 presented significant levels of anti-R1 IgA in trachea and bronchi, suggesting that rLTB can stimulate some degree of mucosal immunity even if not delivered by a mucosal route. However, in the present study, piglets intramuscularly vaccinated with rLTB-R1 presented high levels of anti-R1 systemic antibodies, they were not protected. On the other hand, intranasal vaccination of piglets with rLTB-R1 elicited low levels of antiR1 systemic antibodies (1.6 × at 28 days), but it conferred full protection against experimental SMP. The present study demonstrated that intranasal vaccination of piglets with rLTB-R1 conferred protection against experimental SMP. A more detailed analysis of the protective immune response induced by rLTB-R1 in pigs is currently being performed.

Immune responses of mice against recombinant bovine herpesvirus 5 glycoprotein D.

Glycoprotein D (gD) is essential for attachment and penetration of Bovine herpesvirus 5 (BoHV-5) into permissive cells, and is a major target of the host immune system, inducing strong humoral and cellular immune responses. The aim of this study was to evaluate in mice the immunogenicity of recombinant BoHV-5 gD (rgD5) expressed in Pichia pastoris. Vaccines formulated with rgD5 alone or adjuvanted with Montanide 50 ISA V2; Emulsigen or Emulsigen-DDA was administered intramuscularly or subcutaneously. Almost all formulations stimulated a humoral immune response after the first inoculation. The only exception was observed when the rgD5 was administered subcutaneously without adjuvant, in this case, the antibodies were observed after three doses. Higher titers of neutralizing antibodies were obtained with the three oil-based adjuvant formulations when compared to non-adjuvanted vaccine formulations. The rgD5 vaccine stimulated high mRNA expression levels of Th1 (INF-γ) and pro-inflammatory cytokines (IL-17, GM-CSF). The results demonstrated that the recombinant gD from BoHV-5 conserved important epitopes for viral neutralization from native BoHV-5 gD and was able to elicit mixed Th1/Th2 immune response in mice.

Parenteral adjuvant potential of recombinant B subunit of Escherichia coli heat-labile enterotoxin

BACKGROUND The B subunit of Escherichia coli heat-labile enterotoxin (LTB) is a potent mucosal immune adjuvant. However, there is little information about LTB's potential as a parenteral adjuvant. OBJECTIVES We aimed at evaluating and better understanding rLTB's potential as a parenteral adjuvant using the fused R1 repeat of Mycoplasma hyopneumoniae P97 adhesin as an antigen to characterise the humoral immune response induced by this construct and comparing it to that generated when aluminium hydroxide is used as adjuvant instead. METHODS BALB/c mice were immunised intraperitoneally with either rLTBR1 or recombinant R1 adsorbed onto aluminium hydroxide. The levels of systemic anti-rR1 antibodies (total Ig, IgG1, IgG2a, and IgA) were assessed by enzyme-linked immunosorbent assay (ELISA). The ratio of IgG1 and IgG2a was used to characterise a Th1, Th2, or mixed Th1/Th2 immune response. FINDINGS Western blot confirmed rR1, either alone or fused to LTB, remained antigenic; anti-cholera toxin ELISA confirmed that LTB retained its activity when expressed in a heterologous system. Mice immunised with the rLTBR1 fusion protein produced approximately twice as much anti-rR1 immunoglobulins as mice vaccinated with rR1 adsorbed onto aluminium hydroxide. Animals vaccinated with either rLTBR1 or rR1 adsorbed onto aluminium hydroxide presented a mixed Th1/Th2 immune response. We speculate this might be a result of rR1 immune modulation rather than adjuvant modulation. Mice immunised with rLTBR1 produced approximately 1.5-fold more serum IgA than animals immunised with rR1 and aluminium hydroxide. MAIN CONCLUSIONS The results suggest that rLTB is a more powerful parenteral adjuvant than aluminium hydroxide when administered intraperitoneally as it induced higher antibody titres. Therefore, we recommend that rLTB be considered an alternative adjuvant, even if different administration routes are employed.

Effect of the ethanolic extract from green propolis on production of antibodies after immunization against canine parvovirus (CPV) and canine coronavirus (CCoV) / Efeito do extrato etanólico de própolis verde sobre a produção de anticorpos após imunização contra parvovírus canino (CPV) e coronavírus canino (CCoV)

This study was designed to evaluate whether an ethanolic extract of green propolis (EEP) can interfere with p roduction of specific antibodies after immunization against parvovirus (CPV) and canine coronavirus (CCoV). Mice were vaccinated with CPV and CCoV (0.75, 1.5 and 3 x 106 TCID50) with or without 400 μg/dose of the EEP. Twenty one days after the third dose was measured serum IgG. The co-administration of the EEP significantly enhanced serum specific IgG responses to CPV in animals inoculated with the highest concentration of the antigen, and had no influence on levels of antibodies to CCoV. The results indicate that the EEP has immunomodulatory action closely dependent on the type and concentration of antigen used, being able to increase the levels of antibodies to CPV.

Este estudo foi realizado para avaliar se extrato etanólico de própolis verde (EEP) pode interferir na produção de anticorpos específicos após imunização contra parvovírus (CPV) e coronavírus canino (CCoV). Camundongos foramvacinados com CPV e CCoV (0.75, 1.5 e 3 x 106 TCID50) com ou sem 400 μg/dose de EEP. Vinte e um dias após a terceira dose foi mensurado IgG sérica. A coadministração de EEP aumentou significativamente os níveis de IgG específica para o CPV em animais inoculados com a maior concentração do antígeno, e não teve influência sobre os níveis de anticorpos para CCoV. Os resultados indicam que o EEP tem ação imunomoduladora intimamente dependente do tipo e concentração do antígeno utilizado, sendo capaz de aumentar os níveis de anticorpos contra CPV.

Investigation on Newcastle Disease Virus (NDV), Infectious Bursal Disease Virus (IBDV) and Avian Poxvirus (APV) in magellanic penguins in Southern region of Brazil

To investigate the exposure of the Newcastle disease virus (NDV), infectious bursal disease virus (IBDV) and avian poxvirus (APV) in Magellanic penguins found on the beaches in Southern regions of Brazil, the frequency of serum antibodies was estimated in 89 samples taken during 2005 and 2006. All the penguins were negative for the presence of antibodies against NDV by hemagglutination inhibition test and to APV by indirect ELISA. The reactivity was similar to the positives controls using ELISA kit for the IBDV made in the chickens in 50 samples. This reactivity also was demonstrated in 42 samples using agar gel immunodiffusion. No clinical signs related to IBDV infection were observed. The results indicated the absence of infection by NDV and APV but suggested IBDV exposure in the population of penguins studied.