Evaluation of the Humoral Response after Immunization with a Chimeric Subunit Vaccine against Shiga Toxin-Producing Escherichia coli in Pregnant Sows and Their Offspring.

Shiga toxin-producing Escherichia coli (STEC) poses a significant public health risk due to its zoonotic potential and association with severe human diseases, such as hemorrhagic colitis and hemolytic uremic syndrome. Ruminants are recognized as primary reservoirs for STEC, but swine also contribute to the epidemiology of this pathogen, highlighting the need for effective prevention strategies across species. Notably, a subgroup of STEC that produces Shiga toxin type 2e (Stx2e) causes edema disease (ED) in newborn piglets, economically affecting pig production. This study evaluates the immunogenicity of a chimeric protein-based vaccine candidate against STEC in pregnant sows and the subsequent transfer of immunity to their offspring. This vaccine candidate, which includes chimeric proteins displaying selected epitopes from the proteins Cah, OmpT, and Hes, was previously proven to be immunogenic in pregnant cows. Our analysis revealed a broad diversity of STEC serotypes within swine populations, with the cah and ompT genes being prevalent, validating them as suitable antigens for vaccine development. Although the hes gene was detected less frequently, the presence of at least one of these three genes in a significant proportion of STEC suggests the potential of this vaccine to target a wide range of strains. The vaccination of pregnant sows led to an increase in specific IgG and IgA antibodies against the chimeric proteins, indicating successful immunization. Additionally, our results demonstrated the effective passive transfer of maternal antibodies to piglets, providing them with immediate, albeit temporary, humoral immunity against STEC. These humoral responses demonstrate the immunogenicity of the vaccine candidate and are preliminary indicators of its potential efficacy. However, further research is needed to conclusively evaluate its impact on STEC colonization and shedding. This study highlights the potential of maternal vaccination to protect piglets from ED and contributes to the development of vaccination strategies to reduce the prevalence of STEC in various animal reservoirs.

Caracterización de cepas patógenas extraintestinales de Escherichia coli aisladas de perros y gatos de companía de Buenos Aires, Argentina / Characterization of extraintestinal pathogenic Escherichia coli strains isolated from household dogs and cats in Buenos Aires, Argentina

El pangenoma de Escherichia coli se compone de un core conservado y regiones genómicas variables. El componente genético constante permite determinar la filogenia del microorganismo, mientras que la variabilidad genética ha permitido el surgimiento de cepas patógenas intestinales y extraintestinales. En este estudio caracterizamos genéticamente 85 cepas patógenas extraintestinales aisladas de caninos y felinos. Se utilizó el esquema de Clermont para agruparlas en relación con elfilogrupo de pertenencia (intestinal: Ay B1; extraintestinal: B2 y D) y se investigó en ellas la presencia de varios marcadores de virulencia (pap1-2, pap3-4, sfa, afa, hlyA, aer y cnf), así como de marcadores de patovares híbridos. El 69,4% de los aislamientos pertenecieron al filogrupo A; el 1,2% al B1; el 16,5% al B2 y el 12,9% al D. El gen encontrado con mayor frecuencia fue sfa (21/85), seguido de los genes pap1-2 y cnf (20/85) y pap3-4 (19/85). No se detectaron híbridos. Los aislamientos en animales deben ser estudiados debido al potencial zoonótico del microorganismo.

The pangenome of Escherichia coli is composed of a conserved core and variable genomic regions. The constant genetic component allows to determine the phylogeny of the microorganism, while genetic variability promoted the emergence of intestinal pathogenic strains and extraintestinal strains. In this study we characterized 85 extraintestinal pathogenic isolates genetically isolated from canines and felines. We used the Clermont scheme that includes intestinal (A and B1) and extraintestinal (B2 and D) phylogroups, virulence markers (pap1-2, pap3-4, sfa, afa, hlyA, aer and cnf) and hybrid pathogens. A percentage of 69.4% of the isolates belonged to phylogroupA; 1.2% to phylogroup B1; 16.5% to phylogroup B2 and 12.9% to phylogroup D. The most commonly found gene was sfa (21/85), followed by pap1-2 and cnf (20/85) and pap3-4 (19/85). No hybrids were detected. Animal isolates should be studied due to the zoonotic potential of the microorganism.

Escherichia coli shigatoxigénica en animales relacionados con casos de diarreas sanguinolentas o síndrome urémico hemolítico y prevalencia en roedores de la Ciudad de Buenos Aires / Shiga toxin-producing escherichia coli in animals related to cases of bloody diarrhea

Escherichia coli shigatoxigénica (STEC) es un patógeno endémico en Argentina, responsable de diarrea aguda sanguinolenta (DAS) y/o síndrome urémico hemolítico (SUH). La correlación entre SUH y alimentos contaminados ha sido documentada, aunque no siempre se estableció la fuente de infección. La ruta de contagio persona-persona es relevante. Dados los registros previos de prevalencia de STEC en animales de compañía y los hábitos de convivencia humano-animal en centros urbanos, es necesario evaluar la ruta mascota-persona. A su vez, los roedores podrían tener un papel epidemiológico en la endemia. OBJETIVO: Estudiar posibles reservorios animales relacionados con casos de SUH/DAS en la Ciudad Autónoma de Buenos Aires y estimar la prevalencia de STEC en roedores. MÉ-TODOS: Se intervino en 28 casos de SUH y 49 de DAS. Se realizó rastrillaje de cepas STEC por PCR a partir de hisopados rectales de los animales vinculados a cada caso. La prevalencia en roedores se estimó por PCR de sus hisopados rectales. RESULTADOS: Se aislaron cepas STEC en 1/10 caninos y 1/3 felinos con vivientes con casos de SUH, y 1/9 felinos contacto con casos de DAS. Rattus rattus fue hospedero de cepas STEC en 33% de los animales capturados en focos de SUH. En roedores, la prevalencia fue de 3,1%. CONCLUSIONES: Las cepas STEC circulan en los animales que conviven o tienen al menos un hábitat compartido con la población en riesgo, quienes podrían participar en la transmisión del agente. Es necesario reevaluar las intervenciones sanitarias en focos y en programas de control de SUH/DAS

Shigatoxigenic Escherichia coli(STEC) is an endemic pathogen in Argentina, which causes bloody diarrhea (BD) and/or hemolytic uremic syndrome (HUS).The co-relation between HUS and contaminated food has been documented, although the source of infection was not always established. Person-to-person route of infection is relevant. Taking into account previous STEC prevalence data in companion animals and the habits of human-animal coexistence in urban centers, it is necessary to evaluate pet-to-person transmission. On the other hand, rodents may also play an epidemiologic role in the endemic transmission. OBJECTIVE: To study potential animal reservoirs related to HUS and BD cases in the City of Buenos Aires and to estimate the prevalence of STEC in rodents. METHODS: An intervention was conducted in 28 cases of HUS and 49 of BD. Screening for STEC was performed by PCR from rectal swabs of linked animals to each case. The prevalence in rodents was estimated by PCR from rectal swabs. RESULTS: STEC strains were isolated in 1/10 dogs and 1/3 cats cohabiting with HUS cases, and in 1/9 cats in contact with DAS cases. Rattus rattus was host of STEC strains in 33% of the animals captured in HUS areas. In rodents, the prevalence was 3.1%. CONCLUSIONS: STEC strains circulate in animals that live withor share at least the same habitat with the population at risk, and could participate in the transmission of the agent. It is necessary to re-evaluate health interventions both in outbreaks and in control programs of HUS/BD

El rol epidemiológico de las mascotas en el ciclo de transmisión urbana de cepas STEC / Epidemiological role of pets in urban transmission cycle of STEC

Escherichia coli is an important constitutional element of both animal's and men's microbiote. Rumiants in general and bovine in particular have been pointed out as reservoirs of shigatoxigenic (STEC) and enterohemorragic strains (EHEC). These strains are rarely reported in pets isolations and are badly documented. Revisions of the pathogenic role of E. coli in small animals, particulary based on intestinal and urogenital isolations, involve in a very low proportion the STEC strains. In dogs, ocasional isolations are reported, from feces coming from both healthy and diarreic dogs. The STEC intestinal strains prevalence in dogs and cats from urban centers, based on the habit of including regular or ocasional raw meat in their diet, should not be understimated.