Respuesta humoral en la hemoncosis ovina : Dinámica de la producción de anticuerpos y caracterización antigénica de "Haemonchus contortus"

Tesis de la Universidad Complutense de Madrid, Facultad de Veterinaria, Departamento de Sanidad Animal, leída el 14-07-1992Se ha estudiado la respuesta humoral del ganado ovino manchego a las infestaciones por Haemonchus Contortus mediante Enzimoinmunoensayo (Elisa), caracterización antigénica por Western Blotting, exploración inicial de antigenicidad cruzada con otros tricostrongiloideos y selección de antígenos de posible valor diagnóstico e inmunoprofiláctico. Se comprobó la falta de capacidad protectora en los corderos (<6-6,5 meses) y una resistencia parcial en los animales mayores ( =1 año). El Elisa IGC permitió el diagnóstico ( 0,41 a405) de la hemoncosis ovina ( 6-6,5 meses). Se apreció el papel de las IGA fecales como marcador de primoinfestación. Se demostró la capacidad de los sueros procedentes de corderos (<6 meses) infestados, para reconocer antígenos del parásito; se observó la variabilidad individual en el reconocimiento y un elevado grado de antigenicidad cruzada con otros trichostrongyloidea; no obstante, se confirmó el valor diagnóstico de un péptido de ca. 25 kda de extracto soluble de adultos de haemonchus contortus en la hemoncosis ovina.Depto. de Sanidad AnimalFac. de VeterinariaTRUEpu

Immunization against Lamb Haemonchosis with a Recombinant Somatic Antigen of Haemonchus contortus (rHcp26/23)

Haemonchosis, caused by the abomasal nematode Haemonchus contortus, is a common parasitic disease of sheep. Our previous results showed that a soluble fraction from adult stages of the nematode (p26/23) induced partial protection against challenge. Recombinant DNA technology was applied to obtain a synthetic protein (rHcp26/23). Immunological assays (ELISA, Western blotting, and immunolocalization), using sera from lambs immunized with p26/23, confirmed the identity of the recombinant protein and demonstrated that the synthetic protein is equivalent to the purified protein employed in the previous immunoprophylaxis studies. Vaccination of lambs with 300 μg of rHcp26/23 and Freund's adjuvant elicited a notable specific antibody response. Immunization did not induce any significant protection after challenge with 16000 infective larvae of H. contortus, and comparable values for parasite faecal egg output, packed cell volume, and abomasal parasite burdens were found in vaccinated and control animals

Respuesta humoral en la hemoncosis ovina : Dinámica de la producción de anticuerpos y caracterización antigénica de "Haemonchus contortus"

Se ha estudiado la respuesta humoral del ganado ovino manchego a las infestaciones por Haemonchus Contortus mediante Enzimoinmunoensayo (Elisa), caracterización antigénica por Western Blotting, exploración inicial de antigenicidad cruzada con otros tricostrongiloideos y selección de antígenos de posible valor diagnóstico e inmunoprofiláctico. Se comprobó la falta de capacidad protectora en los corderos (<6-6,5 meses) y una resistencia parcial en los animales mayores ( =1 año). El Elisa IGC permitió el diagnóstico ( 0,41 a405) de la hemoncosis ovina ( 6-6,5 meses). Se apreció el papel de las IGA fecales como marcador de primoinfestación. Se demostró la capacidad de los sueros procedentes de corderos (<6 meses) infestados, para reconocer antígenos del parásito; se observó la variabilidad individual en el reconocimiento y un elevado grado de antigenicidad cruzada con otros trichostrongyloidea; no obstante, se confirmó el valor diagnóstico de un péptido de ca. 25 kda de extracto soluble de adultos de haemonchus contortus en la hemoncosis ovina

Vaccination of lambs against Haemonchus contortus with the recombinant rHc23. Effect of adjuvant and antigen dose.

Haemonchus contortus is the most pathogenic gastrointestinal helminth of small ruminants. Natural or experimental repeated infections and several native antigens confer a partially protective immune response but vaccination with subunit antigens has been elusive. Promising results have been obtained with a recombinant form of a somatic antigen (rHc23). In this paper we present the results obtained in vaccination trials in lambs using two dosages of rHc23 and standard adjuvants. Six-months old Manchego females lambs were vaccinated with rHc23 (50 or 200 μg/dose) adjuvanted with 1mL aluminum hydroxide on days -42, -28 and -14 or with 200 μg/dose rHc23 and 5 mg Quil A on days -49, -28 and -7. Control lambs were kept receiving only the adjuvants the same days or no treatment. Moreover one group did not receive any treatment or infection. On day 0 vaccinated lambs, untreated animals and those receiving the adjuvant were infected per os with a monospecific single infection of 4000 L3 of H. contortus. Infection was kept for 58 days and follow-up included the determination of serum specific antibody response (ELISA, WB), hematological parameters (eosinophil counts, hematocrit) and fecal egg counts (epg). Absence of hematocrit alterations, reduction of helminth's eggs output and abomasal parasite burden at the end of the experiment were the efficacy criteria of vaccination with the recombinant. Immunization with both adjuvants and antigen dosages elicited strong antibody responses particularly with Quil A. Vaccinated groups showed significant reduction of fecal egg excretion and abomasal helminth burdens. Highest protection of lambs against challenge was achieved with aluminum hydroxide and 200 μg/dose rHc23 with a reduction of over 70% of the abomasal burden and over 80% of fecal egg output. Results suggest that rHc23 could be a valuable recombinant candidate for vaccination against haemonchosis. No clear relationship was found between antibody levels and protection this pointing towards involvement of both humoral and cellular components in the protective response elicited by rHc23

Experimental design of the vaccination trial of lambs vaccinated with rHc23 against <i>Haemonchus contortus</i> challenge.

<p>Experimental design of the vaccination trial of lambs vaccinated with rHc23 against <i>Haemonchus contortus</i> challenge.</p

Cumulative fecal <i>Haemonchus contortus</i> eggs output (AUC 21–49 dpi) of lambs vaccinated with rHc23.

<p>Cumulative fecal <i>Haemonchus contortus</i> eggs output (AUC 21–49 dpi) of lambs vaccinated with rHc23.</p

Fecal egg output of vaccinated lambs with rHc23 after challenge.

<p>Values are geometric means of individual log transformed (log x+1) <i>Haemonchus contortus</i> eggs excretion (eggs per gram, epg) from week 3 post challenge onwards. Individual fecal analyses were performed with a modified McMaster technique. Symbols as in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0193118#pone.0193118.g001" target="_blank">Fig 1</a>.</p

Serum specific IgG response of vaccinated lambs with rHc23 after challenge with 4000 L3 <i>Haemonchus contortus</i>.

<p>Fig 1A: Anti-rHc23 serum IgG response of experimental lambs. Fig 1B: Anti-Adult Soluble Extract of <i>H</i>. <i>contortus</i> (ASE) serum IgG levels along the experiment. Sera were diluted 1/200 and data are mean±standard deviation of the optical density (OD) values found before infection (weeks -7 and -3), the day of the infection (week 0) and weekly afterwards up to week 7 post challenge.</p

Abomasal adult <i>Haemonchus contortus</i> burdens (males, females and total) of vaccinated lambs with rHc23.

<p>Abomasal adult <i>Haemonchus contortus</i> burdens (males, females and total) of vaccinated lambs with rHc23.</p

Haemonchus contortus-sheep relationship: A review

La hemoncosis, causada por el nematodo del abomaso de rumiantes Haernonchus contortus, constituye una de las enfermedades parasitarias más notables del ganado ovino en todo el mundo. Las infecciones provocan síndromes anémicos y de mala digestión/absorción que pueden causar la muerte en los casos agudos y disminución de la producción en las formas crónicas. Las claves principales para la aparición de esta enfermedad son el comportamiento biológico del helminto, su patogenia, además de la respuesta del hospedador. El conocimiento actualizado de estos aspectos permitirá una mayor eficiencia de los métodos de diagnóstico y control del proceso y, como consecuencia, la disminución de los riesgos de aparición de esta enfermedad. La presente revisión analiza y discute algunos aspectos de la relación ganado ovino - H. contortus de interés para disminuir el impacto de esta parasitosis sobre la salud y producción ganaderas.577 - [email protected], caused by the abomasal nematode Haemonchus contortus, is among the most relevant parasitic diseases of small ruminants all over the world. The infections are responsible for anemic and bad digestion/absorption syndromes causing the death of severely infected animals in acute cases and the reduction of production scores in the chronic forms of the disease. The keys for the appearance of the disease include the biological behavior of the helminth and mechanisms of pathogenesis, besides the host's response. The updated knowledge of these aspects would result in a higher efficiency of diagnostic and control methods, thus reducing the risks of appearance of the disease. In the present review, several aspects of the sheep - H. contortus relationship are analyzed with the aim of reducing the impact of this parasitosis on livestock health and productivity