Development of monoclonal antibodies against prM of Dengue virus 4 / Desenvolvimento de anticorpos monoclonais para prM de Dengue vírus 4

Introduction: dengue is a most common mosquito-borne viral disease in the Americas and tropical countries. Objective: in this work, mice were hyperimmunized with DENV 4 antigen to produce monoclonal antibodies (mAbs). Methodology: DENV 4 (GenBank KC806069) was inoculated in C6/36 cell monolayers cultivated in Leibovitz's 15 medium supplemented with 5% fetal bovine serum and incubated at 28 oC. The virus stock was submitted to concentration and ultracentrifugation and stored at -80 oC until use (VC DENV 4). Balb/c mice were injected intraperitoneally with 50µg of DENV-4 and successive intraperitoneal injections of 25 µg of VCDENV 4 with Freund's incomplete adjuvant were performed. The spleen cells were fused to SP2/0 myeloma cells with PEG 1540 and distributed in 96-well microplates with Iscove's modified medium with Hipoxantina­Aminopterina­Timidina. Hybridoma screening by indirect ELISA showed positive results for six mAbs, and their characterization was performed by Western blotting and Indirect Immunofluorescence (IFI) techniques. Results: the six mAbs showed strong recognition of prM (24/29 kDa), and minor reaction to E protein (66 kDa), E/E protein dimer (105 kDa), and NS1 (49 kDa) protein in two mAbs. The use of mAbs anti-prM as a diagnostic tool using IFI has been demonstrated to detect DENV-4 antigen in infected cells or tissues. Conclusion: DENV 4 generate mAbs with strong reactivity to prM with potential use to confirm the presence of DENV 4 antigen in tissues or infected cells.

Introdução: a dengue é uma doença viral transmitida por mosquitos comumente das Américas e países tropicais. Objetivo: neste trabalho, camundongos foram hiperimunizados com antígeno DENV 4 para produzir anticorpos monoclonais (mAbs). Metodologia: DENV 4 (GenBank KC806069) foi inoculado em monocamadas de células C6 / 36 cultivadas em meio Leibovitz 15 suplementado com 5% de soro fetal bovino e incubadas a 28oC. O estoque viral foi submetido à concentração, ultracentrifugação e armazenado a -80 oC (VC DENV 4). Camundongos Balb / c foram injetados intraperitonealmente com 50 µg de VC DENV-4 e injeções intraperitoneais sucessivas de 25 µg de antigeno com adjuvante incompleto de Freund. As células do baço foram misturadas a células SP2/0 com PEG 1540 e distribuídas em microplacas de 96 poços com meio Iscove Modificado em presença de Hipoxantina ­ Aminopterina ­ Timidina. A triagem de hibridomas por ELISA indireto apresentou resultados positivos para seis mAbs, e sua caracterização foi realizada por técnicas de Western blotting e Imunofluorescência Indireta (IFI). Resultados: os seis mAbs mostraram forte reconhecimento de prM (24/29 kDa) e reação menor à proteína E (66 kDa), dímero de proteína E / E (105 kDa) e proteína NS1 (49 kDa) em dois mAbs. O uso de mAbs anti-prM como uma ferramenta de diagnóstico utilizando IFI demonstrou eficacia em detectar o antígeno DENV-4 em células ou tecidos infectados. Conclusão: o mAbs produzidos para DENV 4 demonstraram uma forte reatividade contra prM, e poderiam ser uma ferramenta de uso potencial no diagnóstico de DENV 4 .

Development of a novel NS1 competitive enzyme-linked immunosorbent assay for the early detection of Zika virus infection.

Zika virus (ZIKV) is a flavivirus that has emerged as a global health threat after the 2015 outbreak in the Americas, where devastating congenital defects were documented. There are currently no vaccines to prevent ZIKV infections nor commercially available clinical diagnostic tests demonstrated to identify ZIKV without cross-reactive interference of related flaviviruses. Early diagnosis is critical when treating symptomatic patients and in preventing ZIKV transmission. In this context, the development of sensitive and accurate diagnostic methods are urgently needed for the detection of ZIKV acute infection. The aim of this study consisted of obtaining monoclonal antibodies (mAbs) against denatured monomeric ZIKV Nonstructural protein 1 (ZNS1), a useful diagnostic marker for flavivirus early detection, in order to develop a highly specific and sensitive ZNS1 indirect competitive ELISA (icELISA). The production of hybridomas secreting ZNS1 mAbs was carried out through immunizations with denatured monomeric ZNS1. We selected 1F5 and 6E2 hybridoma clones, which recognized the heat-denatured ZNS1 hexameric form by indirect ELISA. Cross-reaction studies indicated that these mAbs specifically bind to a ZNS1 linear epitope, and that they do not cross-react with the NS1 protein from other related flaviviruses. The 1F5 mAb enabled the development of a sensitive and reproducible icELISA to detect and quantify small amounts of ZNS1 disease marker in heat-denatured human sera. Here, we establish a reliable 1F5 based-icELISA that constitutes a promising diagnostic tool for control strategies and the prevention of ZIKV propagation.

Identification and validation of specific B-cell epitopes of hantaviruses associated to hemorrhagic fever and renal syndrome.

BACKGROUND: Orthohantavirus infection is a neglected global health problem affecting approximately 200,000 people/year, spread by rodent hosts and associated to fatal human diseases, such as hemorrhagic fever with renal syndrome (HFRS) and orthohantavirus cardiopulmonary syndrome (HCPS). Circulation of HFRS-associated orthohantaviruses, such as Seoul, Gou, Amur, Dobrava and Hantaan, are supposed to be restricted to Eurasian countries even though their hosts can be a worldwide distribution. Few confirmed HFRS orthohantavirus infections in humans have been reported in American countries, but due to lower medical awareness of the symptoms of this zoonosis, it could be associated to viral underreporting or to misdiagnosis with several tropical hemorrhagic diseases. Serological evidence of orthohantavirus infections, using enzyme-linked immunosorbent assay for the presence of immunoglobulin M and G against recombinant nucleoprotein protein, remains as an essential assay for viral surveillance. In this study, we aimed to identify in silico immunogenic B-cell linear epitopes present on orthohantavirus nucleoprotein that are exclusive to HFRS-related species. METHODOLOGY/PRINCIPAL FINDINGS: In silico analysis were performed using Seoul orthohantavirus nucleoprotein (SHNP) sequence as a model. Linear B-cell-epitopes on SHNP and its immunogenicity were predicted by BepiPred-2.0 and Vaxijen algorithms, respectively. The conservancy of predicted epitopes was compared with the most clinically relevant HFRS or HCPS-associated orthohantavirus, aiming to identify specific sequences from HFRS-orthohantavirus. Peptide validation was carried out by ELISA using Balb/c mice sera immunized with purified recombinant rSHNP. Peptides cross-reactivity against HCPS orthohantavirus were evaluated using immunized sera from mice injected with recombinant Juquitiba orthohantavirus nucleoprotein (rJHNP). CONCLUSION/SIGNIFICANCE: In silico analysis revealed nine potential immunogenic linear B-cell epitopes from SHNP; among them, SHNP(G72-D110) and SHNP(P251-D264) showed a high degree of sequence conservation among HFRS-related orthohantavirus and were experimentally validated against rSHNP-IMS and negatively validated against rJHNP-IMS. Taken together, we identified and validated two potential antigenic B-cell epitopes on SHNP, which were conserved among HFRS-associated orthohantavirus and could be applied to the development of novel immunodiagnostic tools for orthohantavirus surveillance.

Evaluation on the efficacy and immunogenicity of recombinant DNA plasmids expressing S gene from porcine epidemic diarrhea virus and VP7 gene from porcine rotavirus.

Porcine rotavirus (PoRV) and porcine epidemic diarrhea virus (PEDV) usually co-infect pigs in modern large-scale piggery, which both can cause severe diarrhea in newborn piglets and lead to significant economic losses to the pig industry. The VP7 protein is the main coat protein of PoRV, and the S protein is the main structural protein of PEDV, which are capable of inducing neutralizing antibodies in vivo. In this study, a DNA vaccine pPI-2.EGFP.VP7.S co-expressing VP7 protein of PoRV and S protein of PEDV was constructed. Six 8-week-old mice were immunized with the recombinant plasmid pPI-2.EGFP.VP7.S. The high humoral immune responses (virus specific antibody) and cellular immune responses (IFN-γ, IL-4, and spleen lymphocyte proliferation) were evaluated. The immune effect through intramuscular injection increased with plasmid dose when compared with subcutaneous injection. The immune-enhancing effect of IFN-α adjuvant was excellent compared with pig spleen transfer factor and IL-12 adjuvant. These results demonstrated that pPI-2.EGFP.VP7.S possess the immunological functions of the VP7 proteins of PoRV and S proteins of PEDV, indicating that pPI-2.EGFP.VP7.S is a candidate vaccine for porcine rotaviral infection (PoR) and porcine epidemic diarrhea (PED).

Galectin-8 activates dendritic cells and stimulates antigen-specific immune response elicitation.

Galectin-8 (Gal-8) is a mammalian ß-galactoside-binding lectin, endowed with proinflammatory properties. Given its capacity to enhance antigen-specific immune responses in vivo, we investigated whether Gal-8 was also able to promote APC activation to sustain T cell activation after priming. Both endogenous [dendritic cells (DCs)] and bone marrow-derived DCs (BMDCs) treated with exogenous Gal-8 exhibited a mature phenotype characterized by increased MHC class II (MHCII), CD80, and CD86 surface expression. Moreover, Gal-8-treated BMDCs (Gal-8-BMDCs) stimulated antigen-specific T cells more efficiently than immature BMDCs (iBMDCs). Proinflammatory cytokines IL-3, IL-2, IL-6, TNF, MCP-1, and MCP-5, as well as growth factor G-CSF, were augmented in Gal-8-BMDC conditioned media, with IL-6 as the most prominent. Remarkably, BMDCs from Gal-8-deficient mice (Lgals8-/- BMDC) displayed reduced CD86 and IL-6 expression and an impaired ability to promote antigen-specific CD4 T cell activation. To test if Gal-8-induced activation correlates with the elicitation of an effective immune response, soluble Gal-8 was coadministrated with antigen during immunization of BALB/cJ mice in the experimental foot-and-mouth disease virus (FMDV) model. When a single dose of Gal-8 was added to the antigen formulation, an increased specific and neutralizing humoral response was developed, sufficient to enhance animal protection upon viral challenge. IL-6 and IFN-γ, as well as lymphoproliferative responses, were also incremented in Gal-8/antigen-immunized animals only at 48 h after immunization, suggesting that Gal-8 induces the elicitation of an inflammatory response at an early stage. Taking together, these findings argue in favor of the use of Gal-8 as an immune-stimulator molecule to enhance the adaptive immune response.

Venezuelan and western equine encephalitis virus E1 liposome antigen nucleic acid complexes protect mice from lethal challenge with multiple alphaviruses.

Eastern, Venezuelan and western equine encephalitis viruses (EEEV, VEEV, and WEEV) are mosquito-borne viruses that cause substantial disease in humans and other vertebrates. Vaccines are limited and current treatment options have not proven successful. In this report, we vaccinated outbred mice with lipid-antigen-nucleic acid-complexes (LANACs) containing VEEV E1+WEEV E1 antigen and characterized protective efficacy against lethal EEEV, VEEV, and WEEV challenge. Vaccination resulted in complete protection against EEEV, VEEV, and WEEV in CD-1 mice. Measurements of bioluminescence and plaque reduction neutralization tests (PRNTs) indicate that LANAC VEEV E1+WEEV E1 vaccination is sterilizing against VEEV and WEEV challenge; whereas immunity to EEEV is not sterilizing. Passive transfer of rabbit VEEV E1+WEEV E1 immune serum to naive mice extended the mean time to death (MTD) of EEEV challenged mice and provided significant protection from lethal VEEV and WEEV challenge.

Evaluation of water-in-oil-in-water multiple emulsion and microemulsion as potential adjuvants for immunization with rabies antigen.

Water-in-oil-in-water (W/O/W) multiple emulsions and microemulsions have been studied as potential candidates to be formulated as adjuvants. In this work their application as adjuvants for rabies virus immunization was studied. The humoral response, the effective dose 50 and histology for the developed formulations were evaluated in mice and compared with those from traditional adjuvants. The microemulsion and W/O/W multiple emulsion adjuvants developed were able to induce humoral response in mice and the serum showed good in vivo protection. Compared to the other adjuvants evaluated, microemulsion was shown to be the best candidate for rabies immunization as it presented good potency against the virus and did not appear to cause any local reaction.

Anti-HIV-1 and anti-HBV immune responses in mice after parenteral and nasal co-administration of a multiantigenic formulation.

The cell-mediated immune response to HIV-1 is an essential element of the mechanisms for viral replication control. Currently, most of the vaccine candidates in clinical trials were developed to stimulate HIV-1-specific CD8+ cytotoxic (CTL) and CD4+ T helper (Th) lymphocytes. We have been working on a novel approach to develop a vaccine formulation for HIV-1 using a recombinant multiepitopic protein (named CR3), which comprises CTL and Th epitope-rich regions of HIV-1 from several subtype B isolates, co-inoculated with the hepatitis B virus surface (HBsAg) and core (HBcAg) antigens of the hepatitis B virus (HBV) as adjuvant. According to our studies in mice, the nasal-subcutaneous co-administration of this multiantigenic formulation induces a strong Th1-biased specific response against CR3, CD8+ T cells in mice spleen and IFN-gamma-secreting cells in mesenteric lymph nodes. Cross-reactive p24-specific IFN-gamma-secreting cells in spleen were also detected. Moreover, Nef-specific antibodies were elicited in mice sera which might avoid the toxic effects of this antigen. However, a marginal anti-CR3 antibody response was elicited in vaginal mucosa. Additionally, we observed anti-HBsAg and anti-HBcAg cellular and humoral responses. In this regard, our multiantigenic formulation might provide immunity against HBV as an additional benefic considering the high HIV-1-HBV co-infection rate reported worldwide.

Humanization and mammalian expression of a murine monoclonal antibody against Venezuelan equine encephalitis virus.

The murine monoclonal antibody 1A4A1 can strongly neutralize Venezuelan equine encephalitis virus and is a good candidate for development of humanized antibody. Humanization of 1A4A1 variable domains was achieved by grafting 1A4A1 complementarity-determining regions (CDRs) onto the frameworks of human immunoglobulin germline variable and joining gene segments, whose CDRs have the highest similarities to 1A4A1 ones. The humanized 1A4A1 variable domains were further grafted onto human heavy and light chain constant domains to assemble the whole antibody gene, which was then synthesized and cloned to an adenoviral vector. After expression in HEK 293 cells and purification by protein L column, the humanized antibody was demonstrated to retain antigen-binding specificity and neutralizing activity.

[Hemorrhagic (Marburg, Ebola, Lassa, and Bolivian) fevers: epidemiology, clinical pictures, and treatment].

The evaluation of the biological and epidemiological properties of Ebola, Marburg, Lassa, and Machupo viruses suggests that they are of social importance for health care authorities. The studies have created prerequisites to the development of reliable biosafety means against these pathogens. Particular emphasis is laid on the methods for infection diagnosis and on the studies to design specific protective agents--immunoglobulins and inactivated vaccines.

Ganglioside GM1-binding peptides as adjuvants of antigens inoculated by the intranasal route.

Forty-five GM1-binding peptides were identified using phage-displayed peptides libraries of random peptides. Most have a motif containing a hydrophobic amino acid followed by a serine (S). Based on a GM1-binding assays, two of these GM1-binding peptides (named 15 and 40) were chosen to investigate its immunostimulatory properties when chemically coupled to antigens. Mice intra-nasally (i.n.) vaccinated with some of these complexes developed a better local and systemic antibody response than mice i.n. vaccinated with the respective uncoupled antigens. The efficiency of the complex GM1-binding peptide-antigen strongly depends on the composition and structure of both of the components of the complex.

Rotavirus vp7 antigen produced by Lactococcus lactis induces neutralizing antibodies in mice.

AIMS: To determine if live recombinant Lactococcus lactis strains expressing rotavirus VP7 antigen are immunogenic in mice. METHODS AND RESULTS: Using the food-grade lactic acid bacterium L. lactis as a carrier, we expressed VP7, the major rotavirus outer shell protein and one of the main components of the infective particle, as a cytoplasmic, secreted or cell wall anchored forms. Our results showed that recombinant L. lactis strains secreting VP7 proved to be more immunogenic than strains containing the antigen in the cytoplasm or anchored to the cell wall. CONCLUSIONS: This is the first demonstration that recombinant L. lactis producing VP7 can induce the production of a neutralizing antibody response against rotavirus by the intragastric route. SIGNIFICANCE AND IMPACT OF THE STUDY: Rotaviruses are the single most important aetiological agents of severe diarrhoea of infants and young children worldwide and have been estimated to be responsible for 650 000-800 000 deaths per year of children younger than 5 years old in development countries. Thus, the development of a safe and effective vaccine has been a global public health goal. Although two of five mice orally inoculated with L. lactis strains secreting VP7 elicited a specific-antibody response, these strains could be very useful to be used as a prototype to develop a new generation of protective rotavirus vaccines.

Intranasal immunisation with defective adenovirus serotype 5 expressing the Venezuelan equine encephalitis virus E2 glycoprotein protects against airborne challenge with virulent virus.

There is no vaccine licensed for human use to protect laboratory or field workers against infection with Venezuelan equine encephalitis virus (VEEV). Infection of these groups is most likely to occur via the airborne route and there is evidence to suggest that protection against airborne infection may require high antibody levels and the presence of antibody on the mucosal surface of the respiratory tract. Recombinant defective type 5 adenoviruses, expressing the E3E26K structural genes of VEEV were examined for their ability to protect mice against airborne challenge with virulent virus. After intranasal administration, good protection was achieved against the homologous serogroup 1A/B challenge virus (strain Trinidad donkey). There was less protection against enzootic serogroup II and III viruses, indicating that inclusion of more than one E3E26K sequence in a putative vaccine may be necessary. These studies confirm the potential of recombinant adenoviruses as vaccine vectors for VEEV and will inform the development of a live replicating adenovirus-based VEEV vaccine, deliverable by a mucosal route and suitable for use in humans.

Immunization with a DNA vaccine encoding the hepatitis-C-virus structural antigens elicits a specific immune response against the capsid and envelope proteins in rabbits and Macaca irus (crab-eating macaque monkeys).

In the present study, we evaluated the capability of the plasmid pIDKE2, encoding the HCV (hepatitis C virus) structural proteins Core, E1 and E2, to induce immune response against HCV antigens after injection into rabbits and Macaca irus (crab-eating macaque). Animals were immunized intramuscularly with different amounts of plasmid on weeks 0, 3 and 8. Monkeys received a booster dose on week 46. All rabbits immunized with pIDKE2 generated a positive antibody response and, particularly in rabbits immunized with 2 mg, antibody titres reached values above 1:1500 and 1:400 against the core and the envelope proteins, respectively, 28 weeks after primary immunization. The antibody response in monkeys developed slowly, but antibody titres greater than 1:3500 against HCV structural antigens were detected at week 52. Moreover, anti-E2 antibodies recognized synthetic peptides covering the HVR-1 (hypervariable region-1) from different isolates corresponding to different genotypes. Additionally, a specific lymphoproliferative response against Core and E2 was detected in two out of three monkeys immunized with pIDKE2. The other monkey had a specific proliferative response to E1. Taking all these data together, immunization with pIDKE2 is able to elicit both humoral and cellular immunity against HCV structural antigens in animal models other than mice.

The role of cell-mediated immunity in the pathogenesis of bluetongue virus serotype 11 in the experimental infection of vaccine/sensitized calves.

The cellular immune response of cattle to virulent and avirulent (inactivated) bluetongue virus (BTV) was studied. Each of three calves received three vaccinations (sensitizations) with binary ethyleneimine (BEI)-inactivated BTV, 3 weeks apart. The sensitized animals were challenged with BTV-11 strain UC8 3 weeks after the last vaccination. BTV-seropositive and BTV-seronegative calves were used as controls. The animals were bled weekly for virus isolation and for evidence of cell-mediated immunity (CMI) as determined by the lymphocyte stimulation test (LST). Peripheral blood mononuclear leukocytes (PBM L) cultures were induced with purified BTV antigen; the phytomitogens phytohemagglutinin (PHA), Concanavalin A (ConA) and pokeweed (PKW) mitogen, and combinations of phytomitogens and BTV antigen. LST data were analysed by ANOVA and reported as counts per minute (CPM) and stimulation index (SI). Following BTV challenge exposure, significant SI to mitogens were found in PBML cultures for all animals. BTV antigen induced a weak CMI response. There was evidence of perturbations in lymphocyte response as characterised by a sharp decrease in lymphocyte response to mitogens following combined BTV-antigen and mitogen PBML induction. The SI diminished in PBML cultures after a 4 day incubation period, except for ConA. These results provide evidence that the cell-mediated immune response could be affected by BTV and that inhibitory mediators might play an important role in the pathogenesis of BTV in cattle.

Survival and quality of life in HIV-positive patients treated with a polyantigenic immunomodulator.

A polyantigenic immunomodulator (PAI), previously known as polyantigenic vaccine, which consists of a mixture of antigens of inactivated bacteria with antigens of influenza virus in a peanut-oil-arlacel-A-aluminium monoesterate emulsion, increased tumor resistance and induced tumor regression in tumor bearing mice. This report presents clinical and laboratory data that demonstrate the effect of PAI in long term prolongation of disease free state in HIV positive patients. A total of 40 patients, 35 males and 5 females, with a mean age of 41.1 +/- 10.5 years, ranging from 28 to 68 years, HIV positive by (ELISA and Western Blot), with no restriction on the CD4 + T lymphocytes counts, were included in this open study. The PAI regimen was one subcutaneous injection per week for patients with < 400 CD4 + lymphocytes and one monthly injection for patients with CD4 + count > 400. All patients were monitored at different intervals for lymphocyte counts, clinical condition and treatment toxicity. After a follow up of eight years 81% of the patients were alive and 47% were free of disease. In patients without AIDS, the weight was 153.9 +/- 28 pounds pre-PAI and 164.6 +/- 27 (P = 1.2 x 10(-4); the CD4 + lymphocyte count was 795 +/- 421 pre-PAI and 585 +/- 279 post PAI (P = 0.08). In patients alive with AIDS, the weight was 159.5 +/- 32 pre-PAI and 163.9 +/- 32 pounds post-PAI (P = 0.8); the CD4 + lymphocyte counts was 491 +/- 255 pre-PAI and 298 +/- 142 post-PAI (P = 0.08); and five AIDS-related infections occurred in five patients. In patients who died the weight was 157.7 +/- 23 pre and 146.8 +/- 30 post (P = 0.10); and the CD4 count was 340.7 +/- 149 pre and 103.4 +/- 88 post (P = 0.0057). All died with infection. No toxicity with the use of PAI was reported. PAI improves disease free survival and quality of life in HIV + patients.

Survival and quality of life in HIV-positive patients treated with a polyantigenic immunomodulator

A polyantigenic immunomodulator (PAI), previously known as polyantigenic vaccine, which consists of a mixture of antigens of inactivated bacteria with antigens of influenza virus in a peanut-oil-arlacel-A-aluminium monoesterate emulsion, increased tumor resistance and induced tumor regression in tumor bearing mice. This report presents clinical and laboratory data that demonstrate the effect of PAI in long term prolongation of disease free state in HIV positive patients. A total of 40 patients, 35 males and 5 females, with a mean age of 41.1 +/- 10.5 years, ranging from 28 to 68 years, HIV positive by (ELISA and Western Blot), with no restriction on the CD4 + T lymphocytes counts, were included in this open study. The PAI regimen was one subcutaneous injection per week for patients with < 400 CD4 + lymphocytes and one monthly injection for patients with CD4 + count > 400. All patients were monitored at different intervals for lymphocyte counts, clinical condition and treatment toxicity. After a follow up of eight years 81 percent of the patients were alive and 47 percent were free of disease. In patients without AIDS, the weight was 153.9 +/- 28 pounds pre-PAI and 164.6 +/- 27 (P = 1.2 x 10(-4); the CD4 + lymphocyte count was 795 +/- 421 pre-PAI and 585 +/- 279 post PAI (P = 0.08). In patients alive with AIDS, the weight was 159.5 +/- 32 pre-PAI and 163.9 +/- 32 pounds post-PAI (P = 0.8); the CD4 + lymphocyte counts was 491 +/- 255 pre-PAI and 298 +/- 142 post-PAI (P = 0.08); and five AIDS-related infections occurred in five patients. In patients who died the weight was 157.7 +/- 23 pre and 146.8 +/- 30 post (P = 0.10); and the CD4 count was 340.7 +/- 149 pre and 103.4 +/- 88 post (P = 0.0057). All died with infection. No toxicity with the use of PAI was reported. PAI improves disease free survival and quality of life in HIV + patients

Measurement of antibodies against foot-and-mouth disease virus in a crude antigen suspension and against the via antigen by the quantitative complement fixation test in buffaloes

Anticorpos contra o antígeno associado a infecçäo viral (VIA) e contra suspensöes antigênicas brutas das estirpes "O1" Campo, "A". Venceslau, "A24" Cruzeiro e "C3" Indaial do vírus da febre aftosa (VFA), adquiridos através da imunizaçäo natural passiva dos bufalinos, foram determinados pela reaçäo de fixaçäo de complemento. 3 animais foram testados periodicamente para a presença dos anticorpos até 6 meses de idade. Os resultados mostraram que é perfeitamente possível determinar pela técnica direta de fixaçäo de complemento, anticorpos contra o antígeno VIA e contra diferentes estirpes do VFA em búfalos, de forma satisfatória, característica esta näo observada em bovinos