Gilberto D'Avila Vargas

Avian IgY antibodies: characteristics and applications in immunodiagnostic

Immunoglobulin Y (IgY) is the major antibody isotype in birds, reptiles, amphibia, and lungfish, playing a similar biological role as mammal IgG. Due to its phylogenetic distance, immune diversification and presence in the egg yolk, IgY provide a number of advantages in immunodiagnostic compared to IgG from mammals. Moreover, IgY production is in agreement with international efforts to reduce, refine and if possible, to replace animals in experimentation, contributing substantially in favor of animal welfare. This article presents an overview about structural and functional features, production and applications of IgY in immunodiagnostic, as well as the advantages of chicken antibodies use.

Green propolis phenolic compounds act as vaccine adjuvants, improving humoral and cellular responses in mice inoculated with inactivated vaccines

Adjuvants play an important role in vaccine formulations by increasing their immunogenicity. In this study, the phenolic compound-rich J fraction (JFR) of a Brazilian green propolis methanolic extract stimulated cellular and humoral immune responses when co-administered with an inactivated vaccine against swine herpesvirus type 1 (SuHV-1). When compared to control vaccines that used aluminium hydroxide as an adjuvant, the use of 10 mg/dose of JFR significantly increased (p < 0.05) neutralizing antibody titres against SuHV-1, as well as the percentage of protected animals following SuHV-1 challenge (p < 0.01). Furthermore, addition of phenolic compounds potentiated the performance of the control vaccine, leading to increased cellular and humoral immune responses and enhanced protection of animals after SuHV-1 challenge (p < 0.05). Prenylated compounds such as Artepillin C that are found in large quantities in JFR are likely to be the substances that are responsible for the adjuvant activity.

Avian pox virus infection in a common barn owl (Tyto alba) in southern Brazil

A young common barn owl (Tyto alba) was referred to the Nucleo de Reabilitacao da Fauna Silvestre (Nurfs), Federal University of Pelotas (UFPel), after been found in a barn of a brick factory in the urban area of Pelotas, Rio Grande do Sul, Brazil. The bird was apathic, weak and with crusty lesions in the featherless areas (eyes, beak, legs), and died soon after arrival at Nurfs. Necropsy and histopathological examination of the lesions were carried out. The hyperplasia and hypertrophy of the cutaneous lesions, several eosinophilic intracyto-plasmic inclusion bodies in epithelial cells (Bollinger bodies), as well as particles characteristic of poxvirus, observed by electronic microscopy, confirmed the infection by avian poxvirus, what highlights the importance of Tyto alba as carrier of the virus in the wild.

Antiviral activity of a Bacillus sp: P34 peptide against pathogenic viruses of domestic animals

P34 is an antimicrobial peptide produced by a Bacillus sp. strain isolated from the intestinal contents of a fish in the Brazilian Amazon basin with reported antibacterial activity. The aim of this work was to evaluate the peptide P34 for its in vitro antiviral properties against canine adenovirus type 2 (CAV-2), canine coronavirus (CCoV), canine distemper virus (CDV), canine parvovirus type 2 (CPV-2), equine arteritis virus (EAV), equine influenza virus (EIV), feline calicivirus (FCV) and feline herpesvirus type 1 (FHV-1). The results showed that the peptide P34 exhibited antiviral activity against EAV and FHV-1. The peptide P34 inhibited the replication of EAV by 99.9% and FHV-1 by 94.4%. Virucidal activity was detected only against EAV. When P34 and EAV were incubated for 6 h at 37 °C the viral titer reduced from 104.5 TCID50 to 102.75 TCID50, showing a percent of inhibition of 98.6%. In conclusion, our results demonstrated that P34 inhibited EAV and FHV-1 replication in infected cell cultures and it showed virucidal activity against EAV. Since there is documented resistance to the current drugs used against herpesviruses and there is no treatment for equine viral arteritis, it is advisable to search for new antiviral compounds to overcome these infections.

Serum survey for antibodies to coronavirus, herpesvirus, calicivirus, and parvovirus in domestics cats from Rio Grande do Sul, Brazil.

In Brazil, data regarding the occurrence of feline infections by Feline coronavirus (FCoV), Feline herpesvirus (FHV-1), Feline calicivirus (FCV), and Feline parvovirus (FPV) are scarce (Weiblen et al., 1988; Oliveira et al., 2003; Ruthner et al., 2005), and to this moment there are no scientific reports made in the region of Pelotas, RS, Southern Brazil. FCoV is associated to the development of mild enteritis (Vennema et al., 1998; Hartmann, 2005) or, when FCoV mutants are originated, it can lead to the development of a feline infectious peritonitis (FIP), a progressive systemic disease with a wide spectrum of clinical signs and high mortality rate (Hartmann, 2005). FHV-1 and FCV are agents causing mainly upper respiratory tract diseases, but cats can be infected by these agents without showing clinical signs and become persistent carriers (Maggs et al., 1999; Radford et al., 2007). FPV is highly contagious, inducing an acute disease characterized by leukopenia, fever, depression, dehydration, diarrhea, and vomiting (McKnight et al., 2007). The present study investigated the presence of antibodies against FCoV, FHV-1, FCV, and FPV in the serum samples of 97 domestic cats from Pelotas, Rio Grande do Sul, Southern Brazil. The antibody frequency was analyzed regarding information about age, gender, and habitat that would allow contact with other animals. Serum samples were collected from animals that would be submitted to elective surgeries at the Veterinary Hospital at the Universidade Federal de Pelotas, RS and in five private clinics from the region, from August 2005 to October 2006. Blood samples were collected by cephalic or jugular vein puncturing and sent to the virology and immunology laboratory of UFPel where they were centrifuged for serum separation. The sera were submitted to serum neutralization test (SN) according to Hohdatsu et al. (1999), with a few modifications. Serum serial dilutions from 1:4 to 1:256 were incubated with 100 TCID

Níveis de anticorpos contra o vírus da cinomose canina e o parvovírus canino em cães não vacinados e vacinados

Antibody titres to canine distemper virus (CDV) and canine parvovirus (CPV) were measured in 132 dogs: 80 had been vaccinated at least once, 22 had not been vaccinated, and 30 had unknown vaccination history. Serum antibody titers were measured by means of serum neutralization (CDV) or hemagglutination inhibition (CPV). Serum CDV titers >20 and serum CPV titers >80 were considered protective. Protective antibodies to CDV were present in 40.1% of the population: 39.8% of the vaccinated dogs, 31.8% unvaccinated, and in 46.6% of the dogs with unknown vaccination history. Protective antibodies to CPV were present in 90.9% of the dogs: 93.7% of the vaccinated dogs, 90.9% of the unvaccinated, and 83.3% of the dogs with unknown vaccination history.

Modelagem do crescimento e do desenvolvimento de frangos de corte: validação

A model was developed in order to simulate the basal metabolism, deposition of protein in carcass and feathers and carcass fat deposition. The model assumes the existence of a pool of readily available nutrients in the animal body, being the simulation of animal metabolism based on the in and out flow of nutrients of this pool. Nutrients come from feed intake or tissue catabolism, and may be used for maintenance, feather and carcass protein deposition and carcass fat deposition. The simulation process is dynamic, with maintenance and tissue turnover occurring simultaneously. Three data sets were used for calibration, sensibility analysis and validation of model. The model is able to simulate deposition of protein and fat in the carcass and protein in the feathers. However, adjustments are required to match different genotypes, mainly for the rate of maturing of the protein in the carcass (BP), rate of maturing of the protein in the feathers (BF), for the mature weight of the protein in the carcass (WmP) and the mature weight of the protein in the feathers (WmF). The model was especially shown sensitive to these parameters in the sensibility analysis, being highlighted the importance of being correctly determined. The protein deposition in the carcass and in the feathers they presented smaller correlation coefficients (r2) among the observed values and simulated in function of the great variation among genotypes, what reinforces the need to determine the parameters that characterize each genotype correctly.

PROPOLIS: A NATURAL PRODUCT AS AN ALTERNATIVE FOR DISINFECTION OF EMBRYONATED EGGS FOR INCUBATION

During the cooling process of embryonated eggs, there is a natural air flux from the surface to the inner part of the eggs, carrying contaminants such as bacteria and fungi through the shells pores, infecting embryos and resulting in the inability to hatch or poor chick quality. Formaldehyde, a toxic product, is still the most used disinfectant for embryonated eggs in the aviculture industry. In order to evaluate the antimicrobial activity of the green propolis ethanolic extract as an alternative to formaldehyde, 140 hatching eggs from laying hens were collected and submitted to disinfection with five different treatments: T1 - without disinfection; T2 - formaldehyde fumigated eggs; T3, T4 and T5 disinfection by immersion in propolis solution in the concentrations of 2,400 µg, 240 µg and 24 µg, respectively. The contamination levels by total mesophiles and fungi of the egg shells (Aspergillus sp. and other moulds) after disinfection with propolis were lower than when compared to the control without disinfection. In comparison with formaldehyde, the 240 µg and 24 µg propolis concentrations did not differ regarding antibacterial activity, but for antifungal activity the 2,400 µg and 240 µg concentrations were more efficient. The 2,400 µg and 240 µg propolis treatments presented a hatching rate of 94.1%, compared to only 84.6% for the formaldehyde treatment. The green propolis ethanolic extract presented antibacterial and antifungal activities in embryonated eggs showing that it can be a new natural disinfectant product substituting formaldehyde.

Modelo de simulação do crescimento e desenvolvimento de frangos de corte: descrição e implementação

A model was developed to simulate the basal metabolism, deposition of protein in carcass and feathers, and carcass fat deposition. The model assumes the existence of a pool of readily available nutrients in the animal, simulating metabolism based on the flow of nutrients to and from this pool. Nutrients are originated from feed intake or tissue catabolism, and may be used for maintenance, feather and carcass protein deposition and carcass fat deposition. The simulation process is dynamic, with maintenance and tissue turnover occurring simultaneously. In case energy is insufficient for maintenance, lean and fat tissues are catabolized, and their energy is added to the pool. Nitrogen (N) is also required for maintenance and lean tissue growth. In case of N deficiency, this nutrient is obtained from muscle catabolism. Feather and lean tissue growth is dependent on genetic background and on the largest nutritional limitation (nitrogen or energy) in the nutrient pool. The amount of fat tissue stored depends on the energy available in the pool, being greater when there is excess energy. The effect of sex and different genotypes is expressed through changes in the parameters. The model is able to simulate deposition of protein and fat in the carcass and protein in the feathers.

Atividade do peptídeo antimicrobiano P34 contra o alfaherpesvírus bovino tipo 1

Previous studies have demonstrated the antimicrobial activity of the peptide P34. In this study, the antiviral potential of P34 and the in vitro mechanism of action were investigated against bovine alphaherpesvirus type 1 (BoHV1). P34 exhibited low toxicity, a high selectivity index (22.9) and a percentage of inhibition of up to 100% in MDBK cells. Results from antiviral assays indicated that P34 did not interact with cell receptors, but it was able to inhibit the viral penetration immediately after pre-adsorption. In addition, BoHV1 growth curve in MDBK cells in the presence of P34 revealed a significant reduction in virus titer only 8h post-infection, also suggesting an important role at late stages of the replicative cycle. Virucidal effect was observed only in cytotoxic concentrations of the peptide. These findings showed that the antimicrobial peptide P34 may be considered as a potential novel inhibitor of in vitro herpesviruses and must encourage further investigation of its antiherpetic activity in animal models as well as against a wide spectrum of viruses.