Polymerase Chain Reaction Directed to Eimeria ITS1 rDNA or a Single-Copy Orthologue Corroborates Standard Micro-oocyst Analysis of Intestinal Tissue from Chickens Infected with E. acervulina, E. maxima, or E. tenella.

The purpose of this study was to compare micro-oocyst counts of Eimeria to PCR analysis of intestinal DNA from smears of duodenum, jejunum/ileum, and cecum of chickens infected with Eimeria acervulina, Eimeria maxima, or Eimeria tenella oocysts. Broiler chicks were infected in triplicate with various doses of E. acervulina, E. maxima, or E. tenella oocysts and were necropsied 5-6 days later to recover duodenal, jejunal, or cecal tissue for micro-oocyst count and for DNA recovery. Micro-oocyst counts were done independently by three individuals. Micro-oocyst counts and PCR directed to ITS1 rDNA or to a single-copy orthologue (SCO 5995) displayed a linear relationship with oocyst dose for each Eimeria species. A strong correlation was found between mean micro-oocyst counts and both PCR assays for E. acervulina (r = 0.78-0.94), E. maxima (r = 0.79-0.91), and E. tenella (r = 0.85-0.96). There was good agreement between ITS1 and SCO 5995 PCR assays: E. acervulina (r = 0.92), E. maxima (r = 0.79), and E. tenella (r = 0.93). However, only ITS1 PCR analysis corroborated micro-oocyst counts of Eimeria oocyst DNA recovered from Eimeria-infected broiler chickens submitted to a poultry diagnostic laboratory. These findings suggest that ITS1 PCR or SCO PCR can validate traditional micro-oocyst counts used in quantifying Eimeria infection in chickens. Additional studies may provide a method for estimating the relative abundance of each Eimeria species in a natural infection.

Reacción en cadena de la polimerasa dirigida al gene ITS1 rDNA de Eimeria o a un ortólogo de copia única corrobora el análisis estándar de microquistes del tejido intestinal de pollos infectados con E. acervulina, E. maxima o E. tenella. El propósito de este estudio fue comparar los recuentos de micro-ooquistes de Eimeria con el análisis PCR del ADN intestinal de frotis de duodeno, yeyuno/íleon y ciego de pollos infectados con ooquistes de Eimeria acervulina, Eimeria maxima o Eimeria tenella. Los pollos de engorde se infectaron por triplicado con varias dosis de ooquistes de E. acervulina, E. maxima o E. tenella y se les realizó la necropsia entre los cinco y seis días después para recuperar tejido duodenal, yeyunal o cecal para el recuento de micro-ooquistes y para la recuperación de ADN. Los recuentos de micro-ooquistes se realizaron de forma independiente por tres personas. Los recuentos de micro-ooquistes y la PCR dirigida al gene ITS1-rDNA o a un ortólogo de copia única (SCO 5995) mostraron una relación lineal con la dosis de ooquistes para cada especie de Eimeria. Se encontró una fuerte correlación entre el recuento medio de micro-ooquistes y ambos ensayos de PCR para E. acervulina (r = 0.78­0.94), E. maxima (r = 0.79­0.91) y E. tenella (r = 0.85­0.96). Hubo una buena concordancia entre los ensayos de PCR ITS1 y SCO 5995: E. acervulina (r = 0.92), E. maxima (r = 0.79) y E. tenella (r = 0.93). Sin embargo, solo el análisis ITS1 PCR corroboró los recuentos de micro-ooquistes de ADN de ooquistes de Eimeria recuperados de pollos de engorde infectados con Eimeria enviados a un laboratorio de diagnóstico avícola. Estos hallazgos sugieren que los métodos de ITS1 PCR o SCO PCR pueden validar los recuentos tradicionales de micro-ooquistes utilizados para cuantificar la infección por Eimeria en pollos. Estudios adicionales pueden proporcionar un método para estimar la abundancia relativa de cada especie de Eimeria en una infección natural.

Immunopathology and cytokine responses in broiler chickens coinfected with Eimeria maxima and Clostridium perfringens with the use of an animal model of necrotic enteritis.

The incidence of necrotic enteritis (NE) due to Clostridium perfringens (CP) infection in commercial poultry has been increasing at an alarming rate. Although pre-exposure of chickens to coccidia infections is believed to be one of the major risk factors leading to NE, the underlying mechanisms of CP virulence remain undefined. The objectives of this study were to utilize an experimental model of NE produced by Eimeria maxima (EM) and CP coinfection to investigate the pathologic and immunologic parameters of the disease. Broilers coinfected with EM plus CP exhibited more severe gut pathology compared with animals given EM or CP alone. Additionally, EM/CP coinfection increased the numbers of intestinal CP bacteria compared with chickens exposed to an identical challenge of CP alone. Coinfection with EM and CP repressed nitric oxide synthase gene expression that was induced by EM alone, leading to lower plasma NO levels. Intestinal expression of a panel of cytokine and chemokine genes following EM/CP coinfection showed a mixed response depending on the transcript analyzed and the time following infection. In general, IFN-alpha, IFN-gamma, IL-1beta, IL-2, IL-12, IL-13, IL-17, and TGF-beta4 were repressed, whereas IL-8, IL-10, IL-15, and LITAF were increased during coinfection compared with challenge by EM or CP alone. These results are discussed in the context of EM and CP to act synergistically to create a more severe disease phenotype leading to an altered cytokine/chemokine response than that produced by infection with the individual pathogens.