Evaluation of Clinical and Immunopathological Features of Different Infective Doses of Trypanosoma cruzi in Dogs during the Acute Phase

Infection with Trypanosoma cruzi is a major risk in Latin America, and dogs are believed to be good models for evaluating Chagas disease. Here, we evaluated the clinical and immunopathological alterations developed by mongrel dogs experimentally infected with different infective doses (2,000, 20,000, and 200,000 metacyclic trypomastigotes of Sylvio X10/4 strain kg−1 via intraperitoneal). Clinical and electrocardiographic parameters, as well as antibody production and pathologic lesions were evaluated. All three doses of this strain of T. cruzi induced a similar pattern of infection characterized by cardiac arrhythmias and severe and diffuse myocarditis. Specific anti-T. cruzi IgG indicated seroconversion by day 14 after infection, and IgG levels increased during the period of evaluation. Mortality was observed only in dogs infected with the medium or high parasite doses, but not in the group infected with a low dose of 2,000 parasites kg−1. Infection with a low dose of parasites provides an excellent nonlethal model to evaluate the immunopathology of the acute disease in dogs infected with the Sylvio X10/4 strain of T. cruzi

Testing the Efficacy of a Multi-Component DNA-Prime/DNA-Boost Vaccine against Trypanosoma cruzi Infection in Dogs

Immunization of dogs with DNA-prime/DNA-boost vaccine (TcVac1) enhanced the Trypanosoma cruzi-specific type 1 antibody and CD8+ T cell responses that resulted in an early control of acute parasitemia and a moderate decline in pathological symptoms during chronic phase. Further improvement of vaccine-induced immunity would be required to achieve clinical and epidemiological benefits and prevent transmission of parasites from vaccinated/infected dogs to triatomines

Direct-fed microbes: A tool for improving the utilization of low quality roughages in ruminants

Due to probable toxicity problems to the host animals, these feed additives are not routinely used (Salem et al. 2014a, b). Recently, a great awareness from public health aspects such as residues of these chemicals in milk and meat, and bacterial resistance to antibiotics as a result of increased use in the food chains prohibits their use as feed additives (Barton 2000). These supplements have been criticized by the consumers’ organizations on the ground of product safety and quality. The consumers’ demands have stimulated to search for natural alternatives to chemical feed additives. Supplementation with probiotics that can survive in the rumen has become a suitable alternative (Fon and Nsahlai 2013).For many years, ruminant nutritionists and microbiologists have been interested in manipulating the microbial ecosystem of the rumen to improve production efficiency of different ruminant species. Removal and restriction of antibiotics subtherapeutic uses from ruminant diets has amplified interest in improving nutrient utilization and animal performance and search for more safe alternatives. Some bacterial and fungal microorganisms as a direct-fed microbial (DFM) can be the most suitable solutions. Microorganisms that are commonly used in DFM for ruminants may be classified mainly as lactic acid producing bacteria (LAB), lactic acid utilizing bacteria (LUB), or other microorganism’s species like Lactobacillus, Bifidobacterium, Enterococcus, Streptococcus, Bacillus, Propionibacterium, Megasphaera elsdenii and Prevotellabryantii, in addition to some fungal species of yeast such as Saccharomyces and Aspergillus. A definitive mode of action for bacterial or fungal DFM has not been established; although a variety of mechanisms have been suggested. Bacterial DFM potentially moderate rumen conditions, and improve weight gain and feed efficiency. Fungal DFM may reduce harmful oxygen from the rumen, prevent excess lactate production, increase feed digestibility, and alter rumen fermentation patterns. DFM may also compete with and inhibit the growth of pathogens, immune system modulation, and modulate microbial balance in the gastrointestinal tract. Improved dry matter intake, milk yield, fat corrected milk yield and milk fat content were obtained with DFM administration. However, the response to DFM is not constant; depending on dosages, feeding times and frequencies, and strains of DFM. Nonetheless, recent studies have supported the positive effects of DFM on ruminant performance

Effects of adrenocorticotropic hormone challenge and age on hair cortisol concentrations in dairy cattle

Dairy cattle suffer stress from management and production; contemporary farming tries to improve animal welfare and reduce stress. Therefore, the assessment of long-term hypothalamic-pituitary-adrenal function using non-invasive techniques is useful. The aims in this study were: to measure cortisol concentration in cow and calves hair by radioimmunoassay (RIA), to test cortisol accumulation in bovine hair after adrenocorticotropic hormone (ACTH) challenges, and determine the influence of hair color on cortisol concentrations. Fifteen Holstein heifers were allotted to 3 groups ( n = 5 each): in control group (C), just the hair was sampled; in the saline solution group (SS), IV saline solution was administered on days 0, 7, and 14; and the ACTH group was challenged 3 times with ACTH (0.15 UI per kg of body weight) on days 0, 7, and 14. Serum samples from the SS and ACTH groups were obtained 0, 60 and 90 min post-injection. Serum cortisol concentration was greater 60 and 90 min after injection with ACTH. Hair was clipped on days 0, 14, 28, and 44. Hair cortisol was methanol extracted and measured by RIA. Hair cortisol was preserved for 11 mo. Hair cortisol concentrations in the ACTH group were greater than in the saline and control groups on days 14 and 28, but not on day 44. Concentrations were greater in calves than in cows and greater in white hair than in black hair. Cortisol accumulated in bovine hair after ACTH challenges, but the concentration was affected by both age and hair color. If hair color effects are taken into account, assessing cortisol concentration in hair is a potentially useful non-invasive method for assessing stress in cattle

Effects of Saccharomyces cerevisiae at direct addition or pre-incubation on in vitro gas production kinetics and degradability of four fibrous feeds

The aim of this study was to determine effects of increasing doses of the yeast (Saccharomyces cerevisiae) in two methods of applications (direct or 72 h of pre-incubation) on in vitro GP, degradability and some ruminal fermentation parameters of the fibrous feedstuffs of corn stover, oat straw, sugarcane bagasse, and sorghum straw.The objective of this study was to evaluate the effects of Saccharomyces cerevisiae on in vitro gas production (GP) kinetics and degradability of corn stover, oat straw, sugarcane bagasse and sorghum straw. Feedstuffs were incubated with different doses of yeast [0, 4, 8 and 12 mg/g dry matter (DM)] at direct addition or 72 h pre-incubation. Rumen GP was recorded at 2, 4, 6, 8, 10, 12, 14, 24, 30, 48, 54 and 72 h of incubation. After 72 h, rumen pH and methane were determined and contents were filtrated for DM, neutral (NDF) and acid detergent fibre (ADF) degradability. Fibrous species×method of application×yeast interactions occurred (P<0.001) for all measured ruminal GP parameters and degradability. The direct addition or 72 h pre-incubation of S. cerevisiae with corn stover improved (P<0.05) GP and methane and decreased (P<0.05) the lag time (L) and NDF degradability (NDFD). The direct addition of S. cerevisiae to oat straw increased (P<0.05) rate of GP (c) and decreased (P<0.05) asymptotic GP (b). However, 72 h pre-incubation increased (P<0.05) c with linearly decreased b, DM degradability (DMD) and NDFD. Applying S

Lipofection improves gene targeting efficiency in E14 TG2a mouse embryonic stem cells

Electroporation has been the method of election for transfection of murine embryonic stem cells for over 15 years; however, it is a time consuming protocol because it requires large amounts of DNA and cells, as well as expensive and delicate equipment. Lipofection is a transfection method that requires lower amounts of cells and DNA than electroporation, and has proven to be effi cient in a large number of cell lines. It has been shown that after lipofection, mouse embryonic stem cells remain pluripotent, capable of forming germ line chimeras and can be transfected with greater effi ciency than with electroporation; however, gene targeting of mouse embryonic stem cells by lipofection has not been reported. The objective of this work was to fi nd out if lipofection can be used as effi ciently as electroporation for regular gene targeting protocols. This context compares gene targeting effi ciency between these techniques in mouse embryonic stem cells E14TG2a, using a gene replacement type vector. No differences were found in gene targeting effi ciency between groups; however, lipofection was three times more effi cient than electroporation in transfection effi ciency, which makes lipofection a less expensive alternative method to produce gene targeting in mouse embryonic stem cells

The Use of Peptides in Veterinary Serodiagnosis of Infectious Diseases: A Review

Peptides constitute an alternative and interesting option to develop treatments, vaccines, and diagnostic tools as they demonstrate their scope in several health aspects; as proof of this, commercial peptides for humans and animals are available on the market and used daily. This review aimed to know the role of peptides in the field of veterinary diagnosis, and include peptide-based enzyme-linked immunosorbent assay (pELISA), lateral flow devices, and peptide latex agglutination tests that have been developed to detect several pathogens including viruses and bacteria of health and production relevance in domestic animals. Studies in cattle, small ruminants, dogs, cats, poultry, horses, and even aquatic organisms were reviewed. Different studies showed good levels of sensitivity and specificity against their target, moreover, comparisons with commercial kits and official tests were performed which allowed appraising their performance. Chemical synthesis, recombinant DNA technology, and enzymatic synthesis were reviewed as well as their advantages and drawbacks. In addition, we discussed the intrinsic limitations such as the small size or affinity to polystyrene membrane and mention several strategies to overcome these problems. The use of peptides will increase in the coming years and their utility for diagnostic purposes in animals must be evaluated

Caracterización molecular de aislados de Trypanosoma cruzi de triatominos recolectados en los municipios del Estado de Hidalgo, México

Trypanosoma cruzi (T. cruzi), has been classified into six lineages using molecular typing markers, which are easily amplified by the polymerase chain reaction (PCR) technique. The objective of this work was to identify and geographically locate the isolates of T. cruzi that circulate naturally in triatomines of the municipalities of the State of Hidalgo, Mexico, through the amplification from the conserved region of the mini-exon gene by end point PCR. Method: 170 specimens of hematophagous insects from 14 municipalities from the state of Hidalgo, Mexico, were collected. Optic microscopy and PCR from triatomine fecal and digestive tissue samples were used for laboratory diagnostic of T. cruzi infection and T. cruzi lineage classification. Results: Three triatomines taxas were found: Triatoma dimidiata (87/170), Triatoma mexicana (14/170) y Triatoma gerstaeckeri (7/170). For 36.47% (62/170) of the collected specimens, species could not be determined and were classified as T. spp. T. cruzi infection was determined in 1.76% of the collected specimens through optic microscopy and in 11.18% through PCR. All the classified parasites correspond to the TcI biotype of T. cruzi. Most abundant populations of triatomines (80.58%), as well as, the highest percentage (10.58%) of T. cruzi infected insects, were found in the peridomestic ecotope. Conclusion: The most important vector found in the región of study was Triatoma dimidiata, followed by T. mexicana and T. gerstaekeri and the only T. cruzi biotype found to be infecting triatomines was TcI. The vectors were mainly distributed in the peridomiciliary habitats of the studied municipalities. Results indicate a T. cruzi represents a risk of infection for the inhabitants of the studied regions of the state of Hidalgo, Mexico.Trypanosoma cruzi (T. cruzi), está clasificado en seis linajes mediante marcadores moleculares de tipificación, que son fácilmente amplificados por técnicas de biología molecular. El objetivo del trabajo fue identificar y ubicar geográficamente a los aislados de T. cruzi que infectan naturalmente a los triatominos de los municipios del Estado de Hidalgo a través de la técnica de PCR, que amplifica fragmentos de la región intergénica del gen mini-exón. Método: Se recolectaron 170 muestras de insectos hematófagos en 14 municipios del Estado de Hidalgo, México. El diagnóstico de laboratorio en las muestras de heces y de tejido digestivo de los triatominos, se realizó de manera convencional por microscopia óptica y por la técnica de PCR para determinar la presencia o ausencia de T. cruzi y para la identificación del linaje correspondiente del parásito. Resultados: Se identificaron tres taxones de triatominos: Triatoma dimidiata (87/170), Triatoma mexicana (14/170) y Triatoma gerstaeckeri (7/170). En el 36.47% (62/170) de los especímenes colectados la especie no pudo ser identificada y se clasificaron únicamente como Triatoma spp. Se determinó la presencia del parásito en el 1.76% de los vectores analizados por el método parasitoscópico y en el 11.17% por el método de biología molecular. El total de los parásitos analizados corresponde al biotipo TcI de T. cruzi. En el ecotopo peridoméstico, se encontró la mayor abundancia de triatominos (80.58%) y el mayor porcentaje (10.58%) de infección por T. cruzi. Conclusiones: El vector más importante encontrado en la región en estudio fue Triatoma dimidiata seguido de T. mexicana y T. gerstaekeri y el biotipo con el que están mayormente infectados es el TcI. Los triatominos encontrados se distribuían principalmente en hábitats peridomésticos en los municipios estudiados. Los resultados indican la existencia de riesgo de infección para los habitantes de esas regiones endémicas del Estado de Hidalgo, México