Host transcriptome response to heat stress and Eimeria maxima infection in meat-type chickens.

Eimeria (E.) maxima parasite infects chickens' midgut disrupting the jejunal and ileal mucosa causing high morbidity and mortality. Heat stress (HS) is a seasonal stressor that impacts biological functions leading to poor performance. This study elucidates how HS, E. maxima infection, and their combination affect the ileum transcriptome. Two-hundred and forty 2-week-old males Ross708 chickens were randomly allocated into four treatment groups: thermoneutral-control (TNc), thermoneutral-infected (TNi), heat-stress control (HSc), and heat stress-infected (HSi), with 6 replicates each of 10 birds. Infected groups received 200x103 sporulated E. maxima oocysts/bird, and heat-treated groups were raised at 35°C. At 6-day post-treatment, ileums of five randomly selected chickens per group were sampled, RNA was extracted and sequenced. A total of 413, 3377, 1908, and 2304 DEGs were identified when applying the comparisons: TNc vs HSc, TNc vs TNi, HSi vs HSc, and TNi vs HSi, respectively, at cutoff ≥1.2-fold change (FDR: q<0.05). HSc vs TNc showed upregulation of lipid metabolic pathways and degradation/metabolism of multiple amino acids; and downregulation of most immune-related and protein synthesis pathways. TNc vs TNi displayed upregulation of most of immune-associated pathways and eukaryotic mRNA maturation pathways; and downregulation of fatty acid metabolism and multiple amino acid metabolism pathways including tryptophan. Comparing HSi versus HSc and TNi revealed that combining the two stressors restored the expression of some cellular functions, e.g., oxidative phosphorylation and protein synthesis; and downregulate immune response pathways associated with E. maxima infection. During E. maxima infection under HS the calcium signaling pathway was downregulated, including genes responsible for increasing the cytoplasmic calcium concentration; and tryptophan metabolism was upregulated, including genes that contribute to catabolizing tryptophan through serotonin and indole pathways; which might result in reducing the cytoplasmic pool of nutrients and calcium available for the parasite to scavenge and consequently might affect the parasite's reproductive ability.

Heat Stress Alters the Effect of Eimeria maxima Infection on Ileal Amino Acids Digestibility and Transporters Expression in Meat-Type Chickens.

Eimeria (E.) maxima invades the midgut of chickens and destroys the intestinal mucosa, impacting nutrient digestibility and absorption. Heat stress (HS) commonly affects the broiler chicken and contributes to inflammation and oxidative stress. We examined the independent and combined effects of HS and E. maxima infection on apparent amino acid ileal digestibility (AID) and mRNA expression of amino acid transporters in broiler chickens (Ross 708). There were four treatment groups: thermoneutral-control (TNc) and infected (TNi), heat-stress control (HSc) and infected (HSi), six replicates of 10 birds/treatment. Ileal content and tissue were sampled at 6 d post infection to determine AID and transporters expression. Surprisingly, the HSi chickens exposed to two critical stressors exhibited normal AID. Only the TNi group displayed reduction in AID. Using TNc as control, the HSc group showed upregulated CAT1, LAT4, TAT1, SNAT1, and SNAT7. The HSi group showed upregulated CAT1 and LAT1, and downregulated b0,+AT, rBAT, SNAT1, and SNAT2. The TNi group showed upregulated CAT1, LAT1, and SNAT1 and downregulated B0AT1, b0,+AT, rBAT, LAT4, and TAT1. The expression of all enterocytic-apical and about half of the basolateral transporters was higher in the HSi group than in the TNi group, indicating that HS can putatively alleviate the E. maxima adverse effect on ileal digestion and absorption.

Heat stress modulates the disruptive effects of Eimeria maxima infection on the ileum nutrient digestibility, molecular transporters, and tissue morphology in meat-type chickens.

Eimeria (E.) maxima is one of the most pathogenic Eimeria spp persistently invading the middle jejunum and ileum, damaging the intestinal mucosa of chickens. Heat stress (HS) is a common stressor and equally contributes to inflammation and oxidative stress. We investigated the effect of E. maxima infection and HS on ileal digestibility, mRNA expression of nutrient transporters, and ileal tissue morphology in broiler chickens. There were four treatment groups: thermoneutral control (TNc), thermoneutral infected (TNi), heat stress control (HSc), and heat stress infected (HSi), 6 replicates each of 10 birds per treatment. Chickens were fed a diet containing 0.2% TiO2. At 6-day-post infection, ileal content and tissue were collected to quantify ileal digestibility of crude protein and fat, mRNA levels of nutrient transporters and histopathology. Growth and feed intake were reduced in all treatment groups, compared with the TNc. Contrary to expectation, the combination of two major stressors (E. maxima and HS) in the TNi group exhibited almost normal digestibility while only the TNi birds expressed severe digestibility depression, compared with the TNc group. The TNi group showed the lowest mRNA expression of the transporters: SGLT1, GLUT2-5-8-10-12, FABP1-2-6, and PEPT1 compared with the other treatment groups. The expression of the absorptive enterocytes' gene markers (ACSL5, IAP, and SGLT1) supported by the ileal tissue morphology indicated that the TNi group had the highest enterocytic destruction. The expression of oxidative genes (iNOS and CYBB) dramatically increased only in the TNi group compared with the other treatment groups. Our results showed that exposing broiler chickens to HS can mitigate the disruptive effect of E. maxima on the ileal digestibility and absorption by limiting the parasite-induced tissue injury and suppressing the enterocytic inducible oxidative damage.

Heat stress reduces sexual development and affects pathogenesis of Eimeria maxima in meat-type chickens.

Coccidiosis, caused by Eimeria spp. presents a self-limiting intestinal infection of poultry. Intestinal replication of the parasite causes severe morphological alterations to the host gastrointestinal tract, marked, among others, by the disruption of the intestinal barrier. We have previously reported a significant reduction in merozoite replication and oocyst shedding in E. tenella in vitro and in vivo. The objective of this study was to investigate the pathogenesis of E. maxima infection in broiler chickens under heat stress (HS) and mRNA expression of host cytokines that might affect the curtailed development of the parasite. We herein demonstrate that there is a significant detrimental effect of HS on the pathogenesis of E. maxima infection in broilers. There was a restricted replication of the parasite in HS chickens evidenced by significantly reduced oocyst shedding and disruption of the intestinal blood barrier. Gene expression of parasite genes demonstrated curtailed sexual reproduction of E. maxima in HS chickens. There was downregulation of Eimeria spp. genes related to gamete fusion, oocyst shedding, mitosis and spermiogenesis. Host gene expression indicates alterations in the cytokine expression that could be related to reduced parasite development in vivo.

Attenuation and Protection Efficacy of a Recombinant Infectious Laryngotracheitis Virus (ILTV) Depleted of Open Reading Frame C (ΔORFC) when Delivered in ovo.

In an effort to produce more stable vaccines for infectious laryngotracheitis virus (ILTV), recombinant strains with deletion of genes associated with virulence have been evaluated for attenuation and protection efficacy. Among viral genes associated with virulence, a cluster of five open reading frames (ORFs; A through E) have been identified. An attenuated ILTV recombinant strain with deletion of the ORF C gene induced protection comparable to that elicited by the tissue culture origin (TCO) vaccine when administered via eyedrop. The objective of this study was to evaluate the attenuation and protection efficacy of the ΔORF C strain when delivered in ovo to maternal antibody negative (MAb-) and maternal antibody positive (MAb+) embryos. In ovo delivery of the ΔORF C strain did not affected hatchability or body weight gain, while virus transmission to contact chickens was minor. Nevertheless, nine of ninety (10%) of MAb- chickens vaccinated with the ΔORF C strain showed marked dyspnea, and upon postmortem examination bloody mucoid plugs and high viral genome load were detected in their tracheas. Moreover, the ΔORF C strain induced satisfactory protection in MAb- chickens, but marginal protection in MAb+ chickens after challenge. The reduced protection observed for MAb+ groups of chickens was likely caused by the interference of maternally derived antibodies. This report presents the use of a genetically attenuated ILTV strain delivered in ovo as a potential new approach in the control of ILTV.

Detecção de fatores de virulência de Escherichia coli e análise de Salmonella spp. em psitacídeos / Detection of virulence factors in Escherichia coli and analysis of Salmonella spp. in psittacines

The enteric flora of psittacines is mainly composed of Gram positive bacteria. Gram negative bacteria, like Escherichia coli and Salmonella spp., have a high pathogenic potential and can be considerate as an indicative of management problems that may culminate in disease manifestation due to stress factors, poor diets and overcrowding, in combination with a high bacterial load on the environment. The objective of this study was evaluated the presence of Salmonella spp., Escherichia coli and the virulence genes iss and iutA from E. coli isolates. Forty-four samples were analyzed from psittacines living in captivity, which fifteen samples were from organs fragments of necropsied birds, and twenty-nine were from cloacal and crop swabs of red-spectacled parrots (Amazona pretrei) keeping in captivity. No samples were positive for Salmonella spp. In the samples in which E. coli was detected, both virulence factors (genes iss and iutA) were present.

A flora entérica dos psitacídeos é composta principalmente por bactérias Gram positivas. Bactérias Gram negativas, como Escherichia coli e Salmonella spp., apresentam elevado potencial patogênico, sendo consideradas indicativo de problemas de manejo, que poderão culminar em manifestação de doenças em decorrência de fatores estressantes, dietas deficientes e superlotação, combinados com alta carga bacteriana no ambiente. O objetivo deste trabalho foi avaliar a presença de Salmonella spp., Escherichia coli e os fatores de virulência dos genes iss e iutA dos isolados de E. coli. Analisou-se um total de 44 amostras provenientes de psitacídeos criados em cativeiro, sendo estas 15 fragmentos de órgãos de aves submetidas a exame de necropsia e também 29 amostras de swabs de cloaca e inglúvio de papagaios-charão (Amazona pretrei) criados em cativeiro. Nenhuma amostra foi positiva para Salmonella spp. Nas amostras de E. coli detectou-se ambos os fatores de virulência pesquisados.