Desemmascarant les propietats microbicides i immunoestimuladores de la microbiota fecal del facoquer in vitro i in vivo
- Autores: Jinya Zhang
- Directores de la Tesis: Fernando Rodríguez Pascual (dir. tes.), Jorge Martínez Martínez (codir. tes.), Ana Mª Florencia Correa Fiz (codir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2020
- Idioma: catalán
- ISBN: 9788449094453
- Tribunal Calificador de la Tesis: Rosa Marina Sibila Vidal (presid.), Jordi Marquès Argilaguet (secret.), Carles Ubeda Morant (voc.)
- Programa de doctorado: Programa de Doctorado en Medicina y Sanidad Animales por la Universidad Autónoma de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
African swine fever virus (ASFV) is the number one threat for the pig industry. Until today, there is no commercial vaccine or treatment available, thus complicating the control and eradication of African swine fever (ASF). ASFV can infect domestic pigs (DPs) and Eurasian wild boars (both being Sus Scrofa), resulting in different clinical disease courses, varying from acute ASF with 100 % mortality rate to chronic infection. Conversely ASFV can infect African wild pigs, including warthog, bushpig and giant forest hog, without causing apparent disease.
The work here presented is based on two observations preliminary obtained in our laboratory. Firstly, specific-pathogen-free (SPF) pigs infected with attenuated ASFV strains, developed acute ASF dying in a matter of two weeks, while with same ASFV strains conventional DPs perfectly overcame the infection, despite sharing identical genetic background than the SPF pigs. This definitively demonstrated that together with genetic differences, environmental factors could also play roles in ASF susceptibility. Furthermore, fecal microbiota comparisons between two swine species (pigs and warthogs), grown in diverse environmental conditions, confirmed that microbiota composition varies depending on genetic and environmental factors.
With this data at hand and taking into account that gut microbiota is one of the key players driving body homeostasis equilibrium, immune system maturation and pathogen resistance, the main objective here was to investigate the potential role of warthog fecal microbiota in ASF resistance. We proposed four specific objectives: 1) To establish a fecal microbiota transplantation (FMT) model in DPs using microbiota from DPs or warthogs. 2) To use this animal model to compare the ASF susceptibility after experimental challenge with virulent or attenuated ASFV strains. 3) To isolate individual bacteria from warthog fecal microbiota for further characterization of their in vitro microbicidal or immunostimulatory capabilities, and 4) to inoculate in vivo DPs with selected components of the in vitro characterized microbiota, aiming to mimic the effects observed after FMT.
The main findings obtained can be summarized as follows: (1) Transplantation of fecal microbiota from warthog is not harmful to domestic weaned piglets. (2) FMT from warthog modifies the microbiota composition of transplanted DPs. (3) FMT from warthog improves the mucosal immunity of transplanted DPs, with higher levels of total IgA in sera. (4) FMT from warthog to DPs confers partial protection against intramuscular infection with E75CV1, an attenuated strain. Thus, pigs transplanted with fecal microbiota from warthog, showed a very significant reduction of virus in serum, nasal shedding and clinical signs, while FMT from pigs to pigs did not. No effect was observed against intramuscular challenge with E75, a highly virulent strain. (5) Isolation of individual bacteria from warthog feces allowed the characterization of individual microbiota components in vitro. Therefore, some bacteria showed beneficial properties on pig ileum and colon organoids, others showed microbicidal properties against different pig pathogenic bacteria, including: Clostridium perfringens (type B), Salmonella enterica, Salmonella enterica serovar Typhimurium monophasic variant, Escherichia coli K88 and Streptococcus suis (virulent and apathogenic strains). Several bacteria were able to stimulate in vitro IFNγ secretion by gut associated lymphoid tissues, a key cytokine involved in ASFV protection. (6) The intragastric inoculation of 15 selected isolates strains, improved the mucosal immunity in the recipient animals denoted by the increase in total IgA production in sera and the ASFV-specific IgA in both serum and nasal swabs upon E75CV1 challenge.
The results obtained during the present doctoral thesis will open new avenues for the future fighting not only against ASFV, but also against other pathogens.
