Combination of Live and Inactivated Salmonella Vaccines to Protect Against Fowl Typhoid in Laying Hens.

Fowl typhoid (FT) caused by Salmonella Gallinarum (SG) is a poultry disease distributed worldwide that has been eradicated in commercial production of many developed countries but still persists in many developing countries. Vaccination is one of the main strategies to reduce mortality, clinical signs, and vertical or horizontal transmission. The aim of this work was to assess the protection against FT conferred by vaccines based on Salmonella Enteritidis (SE), SG, or a combination. Five experimental groups of birds, vaccinated with different live or inactivated SG and SE vaccines were included in the trial: 1) two doses of a SG-SE bivalent inactivated vaccine; 2) four doses of the live attenuated SE vaccine; 3) three doses of the live attenuated SE vaccine and two doses of the SG-SE bivalent inactivated vaccine; 4) two doses of the live attenuated SG9R vaccine; and 5) unvaccinated birds. At 28 wk of age, all hens were challenged with a virulent strain of SG, and mortality was recorded during the subsequent 15 days. The results showed that the plan that included only the inactivated vaccine did not show significant protection (P = 1), while the plan based on the administration of the attenuated strain of SE significantly reduced mortality in the group of birds (P = 0.0309). However, the highest levels of protection were obtained in the group of hens immunized with the combination of the inactivated vaccine and the live attenuated SE strain (P < 0.0001), which was statistically similar to the homologous protection conferred by the SG 9R strain, a vaccine used in many countries to control FT. These results demonstrate that the combination of existing vaccines together with strict biosecurity measures on farms may help improve the control of the pathogen in countries where FT in an emerging or reemerging disease.

Nota de investigación- Combinación de vacunas vivas e inactivadas contra Salmonella para proteger contra la tifoidea aviar en gallinas de postura. La tifoidea aviar (FT) causada por Salmonella enterica serotipo Gallinarum biovar Gallinarum (SG) es una enfermedad distribuida en todo el mundo que ha sido erradicada de la producción av'icola comercial de muchos pa'ises desarrollados pero que aún persiste en muchos pa'ises en desarrollo. La vacunación es una de las principales estrategias para reducir la mortalidad, los signos cl'inicos y la transmisión vertical u horizontal. El objetivo de este trabajo fue evaluar la protección contra la tifoidea aviar conferida por vacunas elaboradas con Salmonella enterica serotipo Enteritidis (SE), SG o una combinación de ellas. Se incluyeron en el ensayo cinco grupos experimentales de aves, vacunadas con diferentes vacunas de SG y SE vivas o inactivadas: 1) dos dosis de una vacuna bivalente inactivada de SG y SE; 2) cuatro dosis de la vacuna SE viva atenuada; 3) tres dosis de vacuna SE viva atenuada y dos dosis de vacuna bivalente inactivada SG y SE; 4) dos dosis de la vacuna SG 9R viva atenuada; y 5) aves no vacunadas. A las 28 semanas de edad, todas las gallinas fueron expuestas a una cepa virulenta de SG y se registró la mortalidad durante los 15 d'ias siguientes. Los resultados mostraron que el plan que inclu'ia solo la vacuna inactivada no mostró protección significativa (P=1), mientras que el plan basado en la administración de la cepa atenuada de S. Enteritidis redujo significativamente la mortalidad en el grupo de aves (P = 0,0309). Sin embargo, los mayores niveles de protección se obtuvieron en el grupo de gallinas inmunizadas con la combinación de la vacuna inactivada y la cepa viva atenuada de SE (P < 0,0001), la cual fue estad'isticamente similar a la protección homóloga conferida por la cepa de SG 9R, que es una vacuna utilizada en muchos pa'ises para controlar la tifoidea aviar. Estos resultados demuestran que la combinación de las vacunas existentes junto con estrictas medidas de bioseguridad en las granjas puede ayudar a mejorar el control del patógeno en pa'ises donde la tifoidea aviar es una enfermedad emergente o reemergente.

Clostridium perfringens antigens and challenges for development of vaccines against necrotic enteritis in poultry.

INTRODUCTION: Chickens with Necrotic Enteritis (NE), caused by Clostridium perfringens, exhibit acute and chronic symptoms that are difficult to diagnose, leading to significant economic losses. Vaccination is the best method for controlling and preventing NE. However, only two vaccines based on the CPA and NetB toxins have been commercialized, offering partial protection, highlighting the urgent need for more effective vaccines. OBJECTIVE: This review aimed to identify promising antigens for NE vaccine formulation and discuss factors affecting their effectiveness. METHODS: A systematic review using five scientific databases identified 30 eligible studies through the Rayyan tool, which were included for quality review. RESULTS: We identified 25 promising antigens, including CPA, NetB, FBA, ZMP, CnaA, FimA, and FimB, categorized by their role in disease pathogenesis. This review discusses the biochemical, physiological, and genetic traits of recombinant antigens used in vaccine prototypes, their expression systems, and immunization potential in chickens challenged with virulent C. perfringens strains. Market supply challenges, immunogenic potential, vaccine platforms, adjuvants, and factors related to vaccination schedules-such as administration routes, dosing intervals, and age at immunization-are also addressed. Additionally, the study notes that vaccine formulations tested under mild challenges may not offer adequate field-level protection due to issues replicating aggressive conditions, strain virulence loss, and varied methodologies. CONCLUSIONS: An ideal NE vaccine should incorporate multiple antigens, molecular adjuvants, and delivery systems via in ovo and oral routes. The review underscores the challenges in developing and validating NE vaccines and the urgent need for a standardized protocol to replicate aggressive challenges accurately.

Competitive exclusion products as an antimicrobial alternative to control Salmonella Heidelberg in broilers.

Intestinal infections caused by non-typhoidal Salmonella spp., along with antimicrobial resistance spread are a major food safety concern worldwide. Here, we evaluate the potential of competitive exclusion products developed by anaerobic or aerobic conditions to control systemic infection, cecal colonization, fecal excretion, and improve the intestinal health in broilers challenged by Salmonella Heidelberg (SH). A total of 105 day-old chickens were randomly distributed into three experimental groups: A (untreated control), B (treated with anaerobic culture), and C (treated with aerobic culture). During 21 days, morphometric parameters of the small intestine were analyzed using microscopy, fecal excretions by cloacal swabs, systemic infection, and cecal colonization by colony-forming unit counts (CFU/g). The results indicated the lowest number of positive swabs (45.33%) recovered from Group C, followed by Group B (71.8%) and Group A (85.33%). The bacterial enumeration revealed the lowest amounts in Group C at the necropsy realized in 5-, 7-, and 14-days post-infection (DPI) (P = 0.0010, P = 0.0048, and P = 0.0094, respectively). Statistical differences between intestinal morphometrics were observed in the Group C at 21 DPI. Our results suggest that the product developed under aerobic conditions can improve intestinal health, protecting birds against SH.

Insecticidal activity of fluralaner (Exzolt®) administered to Gallus gallus domesticus against triatomines (Hemiptera, Reduviidae, Triatominae).

BACKGROUND: Triatoma infestans, Triatoma brasiliensis, Triatoma pseudomaculata and Rhodnius prolixus are vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. Chickens serve as an important blood food source for triatomines. This study aimed to assess the insecticidal activity of fluralaner (Exzolt®) administered to chickens against triatomines (R. prolixus, T. infestans, T. brasiliensis and T. pseudomaculata). METHODS: Twelve non-breed chickens (Gallus gallus domesticus) were randomized based on weight into three groups: negative control (n = 4); a single dose of 0.5 mg/kg fluralaner (Exzolt®) (n = 4); two doses of 0.5 mg/kg fluralaner (Exzolt®) (n = 4). Nymphs of 3rd, 4th and 5th instars of R. prolixus, T. infestans, T. brasiliensis and T. pseudomaculata (all n = 10) were allowed to feed on chickens before treatment, and at intervals of 1, 7, 14, 21, 28, 35 and 56 days after treatment, with insect mortality determined. RESULTS: Treatment with two doses of fluralaner showed higher insecticidal efficacy against R. prolixus, T. infestans and T. brasiliensis compared to the single-dose treatment. Similar insecticidal efficacy was observed for T. pseudomaculata for one and two doses of fluralaner. Insecticidal activity of fluralaner (Exzolt®) against triatomine bugs was noted up to 21 and 28 days after treatment with one and two doses of fluralaner, respectively. CONCLUSIONS: The results demonstrate that treatment of chickens with fluralaner (Exzolt®) induces insecticidal activity against triatomines for up to 28 days post-treatment, suggesting its potential use as a control strategy for Chagas disease in endemic areas.

Unlocking the power of Libidibia ferrea extracts: antimicrobial, antioxidant, and protective properties for potential use in poultry production.

Plant extracts are increasingly recognized as potential prophylactic agents in poultry production due to their diverse bioactive properties. This study investigated the phytochemical and biological properties of Libidibia ferrea (L. ferrea), a plant species native to the Caatinga region of northeastern Brazil. The aim of this study was to identify secondary metabolites and to demonstrate the antimicrobial, antioxidant and protective effects of the plant extract. Three extracts were produced: EHMV, a hydroalcoholic extract from the maceration of pods, and EEMC and EEMV ethanolic extracts from the maceration of peels and pods, respectively, from L. ferrea. High-performance liquid chromatography (HPLC-MS/MS) and atomic absorption spectroscopy (AAS) were used to characterize the metabolites and metals. The antimicrobial activity against Salmonella Galinarum (SG), Salmonella pullorum (SP), Salmonella Heidelberg (SH) and Avian pathogenic Escherichia coli (APEC) was evaluated alone and in combination with probiotic bacteria (Bacillus velenzensis) using agar diffusion and the bactericidal minimum concentration (CBM). The antioxidant potential of the extracts was evaluated in 5 in vitro assays and 6 assays in 3t3 cells. The toxicity of EHMV was tested, and its ability to combat SP infection was demonstrated using a chicken embryo model. The results showed that EHMV exhibited significant antimicrobial activity. The combination of EHMV with BV had synergistic effects, increased antimicrobial activity and induced bacterial sporulation. Composition analysis revealed the presence of 8 compounds, including tannins and phenolic compounds. In vitro antioxidant tests demonstrated that total antioxidant capacity(TAC) activity was increased, and the extract had strong reducing power and notable metal chelating effects. Analysis of 3T3 cells confirmed the protective effect of EHMV against oxidative stress. Toxicity assessments in chicken embryos confirmed the safety of EHMV and its protective effect against SP-induced mortality. EHMV from L. ferrea is rich in proteins and contains essential metabolites that contribute to its antimicrobial and antioxidant properties. When associated with probiotic bacteria such as B. velezensis, this extract increases the inhibition of SH, SG, SP, and APE. The nontoxic nature of EHMV and its protective effects on chicken embryos make it a potential supplement for poultry.

Effects of in ovo vaccination time on broiler performance parameters under field conditions.

Hatchery performance is often evaluated based on descriptors such as hatchability, 7-d mortality, and cost. In addition to these descriptors, it is useful to include in this analysis aspects of chick quality through post-hatch performance. Realizing the bird's complete genetic potential necessitates meeting various criteria, with effective support for the chick's immune system being among the pivotal factors. To be effective, in ovo vaccination systems must deliver the vaccines to specific sites in the egg, a circumstance that directly depends on when the injection is made. We examined production data to evaluate the impact of in ovo vaccination time on performance parameters of male Ross308AP chicks. A comprehensive survey was conducted examining records from 3,722 broiler flocks produced and raised by the same company under standard nutrition and management conditions. The selected data specifically pertained to flocks that underwent slaughter between 41 and 45 d. In our analysis, 4 different linear models were built, one for each response variable: mean weight (MW), body weight gain (BWG), corrected feeding conversion rate (cFCR), and total mortality (TM). The linear models used in the analyses included as main predictor the timing of in ovo vaccination (440, 444, 448, 452, 456, 458, and 460 h of incubation), and as additional predictors: age of the breeding flock (26-35, 36-55 and 56-66 wks old), slaughter age, identity of the hatchery, and the season at which the data was collected. Our results showed that the timing of in ovo vaccination significantly affected BWG and cFCR, with procedures performed at 460 h of incubation showing the best outcomes. Breeding flock age affected all response variables, with older breeding flocks delivering increased MW, BWG and TM, and middle-aged flocks increased cFCR. Increasing slaughter age reduced BWG while MW, cFCR and TM were all increased. These data emphasize the benefits of performing in ovo vaccination as close as possible to 460 h of incubation to extract the best BWG and cFCR from Ross308AP male broiler.

Molecular characterization of the meq oncogene of Marek's disease virus in vaccinated Brazilian poultry farms reveals selective pressure on prevalent strains.

Marek's disease virus (MDV) has become an increasingly virulent pathogen in the poultry industry despite vaccination efforts to control it. Brazil has experienced a significant rise of Marek's disease (MD) outbreaks in recent years. Our study aimed to analyze the complete meq gene sequences to understand the molecular epidemiological basis of MD outbreaks in Brazilian vaccinated layer farms. We detected a high incidence rate of visceral MD (67.74%) and multiple circulating MDV strains. The most prevalent and geographically widespread genotype presented several clinical and molecular characteristics of a highly virulent strain and evolving under positive selective pressure. Phylogenetic and phylogeographic analysis revealed a closer relationship with strains from the USA and Japan. This study sheds light on the circulation of MDV strains capable of infecting vaccinated birds. We emphasize the urgency of adopting preventive measures to manage MDV outbreaks threatening the poultry farming industry.

Production and purification of Clostridium perfringens type C beta-toxin and IgG and IgY antitoxins.

OBJECTIVES: This study aimed to produce and purify Clostridium perfringens type C beta-toxin, sheep anti-beta toxin immunoglobulin G (IgG) and chicken immunoglobulin Y (IgY). METHODS: Two methods were used for beta-toxin purification: single-step metal affinity chromatography (MAC) using zinc as a chelator and ion exchange chromatography (IEX). The purified and inactivated beta-toxoids were then administered to sheep and chickens in order to produce IgG and IgY. RESULTS: All assays using the IEX failed. In contrast, MAC purified more than 21 mg of toxin per run in a single-step protocol. The purified and inactivated beta-toxoids were then administered to sheep and chickens, and IgG and IgY were purified with a high yield, medium antibody titer of 50 IU/mL, and high avidity (73.2 %). CONCLUSIONS: C. perfringens type C beta-toxin and sheep or chicken anti-beta toxin IgG and IgY antibodies were successfully produced and purified using a simple protocol. This protocol can be used for the production of components used in the diagnosis and research of necrotic enteritis caused by C. perfringens type C, as well as for the evaluation of existing vaccines and the development of new preventive methods against this disease.

Effects of in ovo injection of bacterial peptides and CpG-ODN on Salmonella enterica serovar Heidelberg infection in specific pathogen-free (SPF) chicks.

RESEARCH HIGHLIGHTS: Peptides + CpG-ODN reduced SH in caeca at the first week post-infection.Administered formulations did not reduce SH-faecal excretion.Levels of intestinal IgA were similar between all groups.CpG-ODN improved some parameters associated with chick intestinal health.

Cellular immune response after vaccination with Salmonella Gallinarum 9R in laying hens and addition of aflatoxin and absorbent in the feed.

Salmonella Gallinarum greatly impacts commercial flocks and vaccination with S. Gallinarum 9R (SG9R) is one of the most effective control strategies in some countries. However, mycotoxins can affect immunization success. Herein, we measured the cellular immune response in SG9R-vaccinated hens, quantified the impact of aflatoxins on the immune response, and determined whether the anti-mycotoxin additive (adsorbent) influences immunity after vaccination. One-day-old chicks of commercial laying hens were raised until 49 days of age and were assigned to six groups. T1 (control group): control diet (no detectable concentration of aflatoxin), no vaccine or adsorbent. T2: vaccine SG-9R at day 28, aflatoxins 2.5 ppm from day 1 to day 49, and adsorbent 2.5 Kg/ton. T3: control diet and vaccine. T4: aflatoxins and vaccine. T5: control diet and aflatoxins. T6: aflatoxins and adsorbent. Body weights were evaluated on days 1, 31, and 41. Cellular immune response was evaluated by flow cytometry at 31, 41, and 49 days of age. T lymphocytes, B lymphocytes, monocytes, phagocytic monocytes and heterophils were evaluated. Aflatoxins suppressed peripheral and mucosal helper T lymphocytes, and mucosal cytotoxic T lymphocytes in vaccinated birds (T2 and T4). However, inclusion of the adsorbent in the feed of vaccinated birds neutralized the effects of aflatoxin (T6). The concentration of immune cells may show differences after SG9R vaccination, particularly an increase in the monocyte concentration. The SG9R vaccine reduced the concentration of activated cytotoxic T lymphocytes, making this marker a good parameter to analyze before and three weeks after immunization.

New Insights into Avian Infectious Bronchitis Virus in Colombia from Whole-Genome Analysis.

Infectious Bronchitis (IB) is a respiratory disease caused by a highly variable Gammacoronavirus, which generates a negative impact on poultry health worldwide. GI-11 and GI-16 lineages have been identified in South America based on Infectious Bronchitis virus (IBV) partial S1 sequences. However, full genome sequence information is limited. In this study we report, for the first time, the whole-genome sequence of IBV from Colombia. Seven IBV isolates obtained during 2012 and 2013 from farms with respiratory disease compatible with IB were selected and the complete genome sequence was obtained by NGS. According to S1 sequence phylogenetic analysis, six isolates belong to lineage GI-1 and one to lineage GVI-1. When whole genome was analyzed, five isolates were related to the vaccine strain Ma5 2016 and two showed mosaic genomes. Results from complete S1 sequence analysis provides further support for the hypothesis that GVI-1, considered a geographically confined lineage in Asia, could have originated in Colombia. Complete genome information reported in this research allow a deeper understanding of the phylogenetic evolution of variants and the recombination events between strains that are circulating worldwide, contributing to the knowledge of coronavirus in Latin America and the world.

Research Note: High genetic diversity of infectious bronchitis virus from Mexico.

The avian infectious bronchitis virus (IBV) is a highly mutable coronavirus that causes an acute and highly contagious disease responsible for economic losses to the poultry industry worldwide. Preventing and controlling bronchitis disease is difficulted by the numerous IBV circulating types with limited antigenic cross-protection that hamper the prevention and control by heterologous vaccines. The coding region of the variable spike S1 receptor-attachment domain is used to classify IBV in 7 genotypes (GI-GVII) comprising 35 viral lineages (1-35). Knowledge of the circulating IBV types causing outbreaks in a specific geographic region is beneficial to select better the appropriate vaccine(s) and contribute to disease control. In the study, 17 avian infectious bronchitis virus strains were obtained from chickens showing signs of illness in Mexico from 2007 to 2021. We detected 4 lineages within genotype I, three already known (GI-3, GI-9, GI-13) and one newly described (GI-30). In addition, we identified 2 divergent monophyletic groups that are tentatively described as lineages of new genotypes (GVIII-1 and GIX-1). Our findings revealed that Mexico's high genetic IBV diversity results from the co-circulation of divergent lineages belonging to different genotypes. Mexican IBV lineages differ significantly from Massachusetts and Connecticut vaccine strains, indicating that the currently used vaccines may need to be updated.

Outbreaks of Avipoxvirus Clade E in Vaccinated Broiler Breeders with Exacerbated Beak Injuries and Sex Differences in Severity.

Avipoxvirus affects chickens and wild birds, and it is characterized by lesions on the nonfeathered parts of the body (the cutaneous form), or necrotic lesions in the upper respiratory tract (the diphtheritic form). In poultry farming, avian pox is usually controlled by live attenuated vaccines. However, there have been many reports of outbreaks, even in flocks of vaccinated birds. In the present study, different outbreaks of the emerging clade E avipoxvirus were detected in commercial breeder flocks of chickens vaccinated against fowlpox virus in Southeast Brazil. Clinical manifestations of these outbreaks included a marked prevalence of moderate to severe progressive lesions in the beaks of affected birds, especially in roosters with increased mortality (up to 8.48%). Also, a reduced hatchability (up to 20.77% fewer hatching eggs) was observed in these flocks. Analysis of clinical samples through light and transmission electron microscopy revealed the presence of Bollinger bodies and poxvirus particles in epithelial cells and affecting chondrocytes. PCR, sequencing, and phylogenetic analysis of major core protein (P4b) and DNA polymerase (pol) genes identified this virus as clade E avipoxvirus. We also developed qPCR assays for open reading frames (ORFs) 49, 114, and 159 to detect and quantify this emergent virus. These results show the arrival and initial spread of this pathogen in the poultry industry, which was associated with harmful outbreaks and exacerbated clinical manifestations in vaccinated commercial breeder flocks. This study also highlights the relevance of permanent vigilance and the need to improve sanitary and vaccination programs.

Interaction between live vaccines for coccidiosis and phytogenic compounds in the diet of broilers.

This study aimed to determine whether live vaccines alone or associated with phytogenic compounds supplied via feed could improve performance, intestinal health, serum biochemistry, and coccidiostatic action in broilers up to 42 days of age, challenged with Eimeria spp., compared with a traditional anticoccidial program. We used 800 birds divided into five treatments of eight repetitions each (n = 20): NC - Negative control (absence of additives in the feed and without coccidian challenge); PC - Positive control (absence of additives and with coccidian challenge at 21 days); AAP - Anticoccidial additives program, including salinomycin and nicarbazine, with coccidian challenge at 21 days of life; VAC - Vaccination on day 1 of life (Hipracox HIPRA®) against coccidiosis and subsequent coccidian challenge at 21 days; VAC + BPC - Vaccination (day 1 of life), the addition of 200 ppm of blend phytogenic compound (BPC) based on carvacrol and cinnamaldehyde to the diet, with coccidian challenge at 21 days of life. The birds in the AAP group more significant weight gain and greater body weight at 21 days than the NC and 42 days of age than the NC and VAC + BPC groups. The excretion of Eimeria oocysts in the excreta of birds was higher in PC than in NC, and in the litter, PC had higher counts than NC, AAP, and VAC + BPC. A higher mean score of intestinal lesions for Eimeria acervulina was observed in VAC and VAC + BPC birds, while for Eimeria maxima, the highest score was found in PC. Higher serum levels of total protein due to the increase in globulins were observed in birds of AAP and VAC than NC. Our findings suggest that vaccination for coccidiosis shortly after the birth of chicks allows performance similar to the conventional coccidiosis control program via diet.

Influence of laying hen-systems and ecologic variables on mites of medical and veterinary importance.

The search for improvements in the poultry production chain and for increased egg productivity have grown significantly. However, intensive production with or by using of confinement systems negatively affect the welfare of animals and is favoring the appearance of harmful ectoparasites in production. Due to differences in the existing management systems, (e.g. Californian and cage-free systems) and given the importance of the poultry industry in the international market, the aim of the present study was: (1) to compare mite community between SIG (Intensive system - cage: Californian) and SIF (Intensive system - free: cage free); (2) egg-laying systems to analyze how the abundances of the ectoparasites Dermanyssus gallinae, Megninia ginlgymura, and Ornithonyssus sylviarum are affected by these egg-laying models; (3) to evaluate the association between the functional diversity found in traps, organic matter, and feathers in both systems; and finally, (4) to analyze how abiotic factors (e.g. humidity, temperature at sampling) affect mite community composition inside each model. A total of 860,571 mites were sampled, belonging to 59 taxa from six functional groups. Mite composition in the SIF system was different from the SIG system, while their variations in dispersion homogeneity were quite similar to each other. Although taxonomic composition is different between them, they are quite similar when clustered according to functional diversity. The variables 'humidity' and 'temperature' were not determining factors for the appearance of species. The species that most contributed for distinguishing the models were: M. ginlgymura, Dermatophagoides farinae, D. gallinae, Tyrophagus putrescentiae, O. sylviarum, Blattisocius keegani, Glycyphagus sp., Acotyledon sp., and Cheyletus malaccensis, respectively. Dermanyssus gallinae was strongly associated with the Californian model. Two taxa were highly correlated with cloaca, neck, dorsum, and inner wings; variations in relative air humidity also affected M. ginlgymura and O. sylviarum populations. Organic matter had a high abundance of predatory mites with potential for controlling mites of sanitary importance in the poultry chain.

Assessment of maternal immunity against Salmonella enterica serovar Heidelberg in progeny of broiler breeders vaccinated with different formulations of bacterins.

RESEARCH HIGHLIGHTSProgeny from vaccinated 30-week-old breeders presented less SH in caecal content compared to the control.High titres of maternal anti-Salmonella IgY could be associated with lower SH faecal shedding.

Impact of farm-level strategies against thermotolerant Campylobacter in broiler chickens, using a quantitative risk assessment model and meta-analysis.

The aim of this study was to evaluate the effect of control strategies (probiotic supplementation and vaccination) at farm on thermotolerant Campylobacter infection due to the consumption of salad cross-contaminated from broiler meat. The broiler food chain was modelled considering the most common practices applied in Argentina (baseline model) and their effect on the prevalence and counts of Campylobacter. Probiotic supplementation and vaccination against Campylobacter spp. were included in different models to evaluate their effectiveness. The parameter distributions of each intervention were obtained based on a systematic review and meta-analysis previously described. The control measures applied at farms were evaluated considering their effectiveness in reducing both the prevalence and the count of thermotolerant Campylobacter in comparison with the baseline model estimation and expressed as relative change in campylobacteriosis risk. Additionally, the identification of the most important input parameters for the model was performed by sensitivity analysis. The model estimated a risk of campylobacteriosis per consumed serving of salad contaminated with poultry meat of 4.99 x 10-3 (95% CI: 6.12 x 10-6 -1.13 x 10-2 ), corresponding to an annual incidence risk estimated of 1,876,009 persons. Scenario analysis indicated that the application of vaccines against Campylobacter (probability of campylobacteriosis = 9.55 x 10-4 ; 95% CI: 5.31 x 10-4 -1.29 x 10-3 ) and the supplementation of broilers with probiotics (probability of campylobacteriosis = 1.32 x 10-3 ; 8.55 x 10-4 -1.69 x 10-3 ) can offer a modest reduction in risk estimates. The intervention efficacy was 80.86% and 73.54% for vaccination and probiotic supplementation, respectively. On-farm interventions were effective to mitigate the risk of campylobacteriosis.

The gut microbiota of chickens in a commercial farm treated with a Salmonella phage cocktail.

The microbiota in broiler chicken intestines affects the animals' health, metabolism, and immunity both positively and negatively. Accordingly, it has a significant impact on animal productivity. Phages, host-specific parasites of bacterial cells, are a promising antimicrobial alternative that selectively target pathogens without disturbing the microbiota. The purpose of this study is to further characterize the commensal microbial community at production scale in broiler chickens treated with a Salmonella phage treatment. We evaluated the cecal microbiota of broilers reared in a commercial farming system where a phage cocktail against Salmonella, SalmoFree was supplied to animals. To do so, two field trials were conducted, incorporating three doses of phages in the broilers' drinking water. Our results showed that the core microbiome (taxa that were present in more than 50% of samples) contained species that are key to microbiota adaptation in the last stage of the production cycle. Among these, there are some important degraders of complex polysaccharides and producers of short chain fatty acids (SCFA) such as Eisenbergiella and Lachnoclostridium. The phage cocktail did not affect the normal development of the microbiota's structure. The addition of the phage cocktail resulted in a significant reduction in Campylobacter and an increase in Butyricimonas, Helicobacter and Rikenellaceae, which are common inhabitants in chicken gut with known negative and positive effects on their health and metabolism. Altogether, we consider that these results contribute valuable information to the implementation of large-scale phage therapy technologies.

Rate of Transfer of Infectious Anaemia Maternal Antibodies from Broiler Breeders To the Progeny: a Field Evaluation

Clinical manifestation of the disease caused by the chicken anaemia virus (CAV) occurs when chicken chicks are vertically contaminated or before the second week of life. CAV control is based on the vaccination of broiler breeders in order to promote progeny protection through maternal antibodies. This work aims to evaluate, under field conditions, the antibody title in commercial broiler breeders at 28, 48, and 68 weeks of age, the rate of transference to the progeny, as well as the duration of antibodies in the progeny up to 21 days of age. Thus, a total of 92 sera samples from 93,000 broiler breeders vaccinated with a live vaccine for CAV at 14 weeks of age and 366 sera samples from their respective progeny were analyzed using ELISA. Breeders' antibody title for CAV ranged between 5051 and 8660, and these titles may provide sufficient protection for their progeny. On average, 63% of the maternal antibodies were transferred to the progeny and lasted up to the second week of chick's life. It is possible to conclude that the vaccine and the vaccination procedure used by this company for breeders against CAV seems to be effective in inducing high antibody levels in the breeders and transfering protective maternal antibodies to the progeny.(AU)

Evaluation of the Efficiency of Commercial Vaccines Against Infectious Bronchitis Virus (IBV) Belonging to the GI-16 Lineage Isolated in an Argentinean Outbreak.

In this study we evaluated the effectiveness of adding serotype 793B vaccine to an immunization program in order to control the infectious bronchitis virus (IBV) GI-16 lineage. Therefore, two different experiments were performed. First, a virus cross-neutralization test was carried out, which indicated that neither the Massachusetts (Mass) nor 793B serotypes are antigenically related to the field isolate A13 (GI-16). We also performed a challenge trial to evaluate if the Mass/793B combination is more efficient than Mass/Connecticut (Conn) to protect chickens against the Argentinian variant A13. Thus, 40 chickens were organized in four groups. Chickens in Group A were vaccinated at 1 day of age with Mass serotype and then at 14 days old with Mass plus Conn serotypes. Chickens in Group B received Mass and 793B serotypes at 1 and 14 days old, respectively. Groups C and D remained unvaccinated. At 28 days of age, Groups A, B, and C were challenged with the A13 isolate, while Group D remained as the negative control. The statistical analysis of the ciliostasis evaluation, performed at 7 days postchallenge (dpch), indicated that the difference between Mass/793B and Mass/Conn was not significant (p > 0.05). However, the comparison against the negative control showed that only Group A was significantly different, suggesting a slightly better performance on blocking ciliostasis for the Mass/793B combination. On the other hand, no significant differences were observed in the viral load, quantified by reverse-transcription quantitative real-time PCR (RT-qPCR) in tracheal swabs and kidneys (at 3 and 7 dpch, respectively) between vaccinated groups. Furthermore, some amounts of the viral genome were found in both vaccinated groups that could indicate that neither the Mass/793B nor the Mass/Conn combinations totally inhibited the viral replication. Such viral replication in vaccinated chickens should seriously be taken into consideration because it could promote the selection of new variants in the future.

Nota de investigación­Evaluación de la eficacia de vacunas comerciales contra el virus de la bronquitis infecciosa (IBV) perteneciente al linaje GI-16 aislado durante un brote argentino. En este estudio se evaluó la efectividad de agregar la vacuna del serotipo 793B a un programa de inmunización para controlar al virus de la bronquitis infecciosa (con las siglas en inglés IBV) linaje GI-16. Por tanto, se realizaron dos experimentos diferentes. Primeramente, se llevó a cabo una prueba de neutralización cruzada de virus, que indicó que ni los serotipos Massachusetts (Mass) ni 793B están antigénicamente relacionados con el aislado de campo A13 (GI-16). También se realizó una prueba de desafío para evaluar si la combinación Massachussets/793B era más eficiente que Massachussets/Connecticut (Conn) para proteger a los pollos contra la variante argentina A13. De esta forma, 40 pollos se organizaron en cuatro grupos. Los pollos del Grupo A se vacunaron al día de edad con el serotipo Massachussets y luego a los 14 días con los serotipos Massachussets más Connecticut. Los pollos del Grupo B recibieron los serotipos Massachussets y 793B a los 1 y 14 días de edad, respectivamente. Los grupos C y D permanecieron sin vacunar. A los 28 días de edad, los Grupos A, B y C fueron desafiados con el aislado A13, mientras que el Grupo D permaneció como control negativo. El análisis estadístico de la evaluación de la ciliostasis, realizada a los 7 días después del desafío (dpch), indicó que la diferencia entre el tratamiento Massachussets/793B y Massachussets/Connecticut no fue significativa (P> 0.05). Sin embargo, la comparación con el control negativo mostró que solo el Grupo A fue significativamente diferente, lo que sugiere un desempeño ligeramente mejor en el bloqueo de la ciliostasis para la combinación Massachussets/793B. Por otro lado, no se observaron diferencias significativas (P> 0.05) en la carga viral, cuantificada mediante transcripción reversa y PCR cuantitativa en tiempo real de hisopos traqueales y riñones (a 3 y 7 días después del desafío, respectivamente) entre los grupos vacunados. Además, se encontraron algunas cantidades del genoma viral en ambos grupos vacunados que podrían indicar que ni las combinaciones Massachussets/793B ni Massachussets/Connecticut inhibieron totalmente la replicación viral. Esta replicación viral en pollos vacunados debe tenerse muy en cuenta porque podría promover la selección de nuevas variantes en el futuro.