Immunity to Rhodococcus equi: antigen-specific recall responses in the lungs of adult horses

Hines, Melissa T.; Paasch, Kathleen; Alperin, Debra C.; Palmer, Guy H.; Westhoff, Nanette C.; Hines, Stephen A.

doi:10.1016/s0165-2427(01)00258-6

Cited by 49 publications

(60 citation statements)

References 25 publications

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“…Adult immune horses showed marked lymphoproliferative responses to recombinant VapA following intrabronchial challenge with virulent R. equi [33], as well as a marked CD4 + and CD8 + T-lymphocyte response, suggesting that both subsets play a role in clearance of infection from the lung, reinforcing also earlier conclusions of the importance of VapA as an immunodominant antigen. Stimulated cells showed significant increases in antigen-specific IFN-γ but not in IL-4 expression, and local levels of IgGa and IgGb isotypes against VapA were dramatically enhanced after challenge, suggesting that these are important correlates of protective immunity.…”

Section: Immunitysupporting

confidence: 82%

Rhodococcus equi

2004

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-Rhodococcus equi is an important cause of subacute or chronic abscessating bronchopneumonia of foals up to 3-5 months of age. It shares the lipid-rich cell wall envelope characteristic of the mycolata, including Mycobacterium tuberculosis, as well as the ability of pathogenic members of this group to survive within macrophages. The possession of a large virulence plasmid in isolates recovered from pneumonic foals is crucial for virulence. The plasmid contains an 27 kb pathogenicity island (PI) that encodes seven related virulence-associated proteins (Vaps), including the immunodominant surface-expressed protein, VapA. Only PI genes are differentially expressed when the organism is grown in macrophages in vitro. Ten of the PI genes, including six Vap genes, have signal sequences, suggesting that they are exported from the cell to interact with the macrophage. Different PI genes are regulated by temperature, pH, iron, oxidative stress and probably also by magnesium, all environmental changes encountered after environmental R. equi are inhaled in dust and are ingested into macrophages in the lung. The basis of pathogenicity of R. equi is its ability to multiply in and eventually to destroy alveolar macrophages. Infectivity is largely or exclusively limited to cells of the monocyte-macrophage lineage. Current evidence suggests that infection of foals with virulent R. equi results in some foals in subversion of cellmediated immunity and development of an ineffective and sometimes lethal Th2-based immune response. Significant progress has been made recently in the development of R. equi-E. coli shuttle vectors, transformation and random and site specific mutagenesis procedures, all of which will be important in molecular dissection of the mechanisms by which R. equi subverts normal macrophage killing mechanisms and cell-mediated immunity.

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Section: Immunitysupporting

confidence: 82%

Rhodococcus equi

2004

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“…Die Beseitigung einer R. equi Infektion beim adulten Pferd ist mit einem signifikanten Anstieg der CD4 + -und CD8 + -T-Lymphozyten in der bronchoalveolären Spülflüssigkeit (BALF), einer Proliferation der Lymphozyten als Antwort auf die R. equi Antigen-Präsentation, der Entwicklung von R. equi spezifischen cytotoxischen T-Lymphozyten, und der Induktion von IFN-g assoziiert (Hines et al 2001. Wäh-rend die CD8 + -T-Lymphozyten im Laufe einer akuten Infektion keine wesentliche Rolle spielen, beteiligen sich die CD4 + -TLymphozyten an der Aktivierung der Alveolarmakrophagen und der IFN-g-Synthese, die zu einer Abtötung des Erregers führen (Kanaly et al 1993(Kanaly et al , 1996.…”

Section: Das Immunsystem Des Pferdes Und Die R Equi-infektionunclassified

Prophylaxis of Rhodococcus equi pneumonia in foals – a review of literature

Schmitz¹,

Block²,

Lämmer³

et al. 2013

PHK

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ZusammenfassungRhodococcus equi (R. equi ) ist ein Bakterium, welches weltweit häufig chronisch verlaufende, abszedierende Bronchopneumonien bei Fohlen im Alter bis sechs Monaten verursacht. Im Gegensatz zu Fohlen entwickeln erwachsene Pferde nur äußerst selten eine Erkrankung durch eine Infektion durch R. equi. Dies liegt daran, dass die Th1-Immunantwort bei Adulten ausgeprägter ist als in der Neugeborenenphase und somit der intrazelluläre Keim auch in den Makrophagen abgetötet wird. Versuche, die Mutterstuten zu impfen haben zwar dazu geführt, dass hohe Konzentrationen an spezifischen Antikörper über das Kolostrum erfolgreich dem Fohlen übertragen wurden, aber die Erkrankungsrate wurde bei den Fohlen auf endemisch betroffenen Betrieben keinesfalls reduziert. Auch die Verabreichung von spezifischem Hyperimmunplasma bewirkt keinen Schutz der Fohlen vor der R. equi-Pneumonie. Diese enttäuschenden Ergebnisse lassen sich dadurch erklä-ren, dass bei einer Infektion der Fohlen mit R. equi die humorale Immunantwort mit spezifischen Antikörpern selbst in hohen Konzentrationen die Tiere nicht vor einer Erkrankung schützt. Es gibt Hinweise dafür, dass die Infektion durch R. equi vielmehr durch Mechanismen der zellulären Immunantwort abgewehrt wird. Weitere Ansätze zur Vorbeugung der R. equi-Pneumonie wie die prophylaktische Verabreichung von Antibiotika bei jungen Fohlen wurden in Erwägung gezogen und geprüft. Insgesamt erwies sich die Behandlung der Fohlen mit Antibiotika in den ersten Lebenswochen nicht als geeignet, um der R. equi-Erkrankung vorzubeugen. Bedauerlicherweise sind die bisherigen Anstrengungen, einen Impfstoff für Fohlen zu entwickeln, erfolglos geblieben. Erste Untersuchungen zeigen, dass Lebendimpfstoffe die Th1-Immunantwort bei Fohlen stimulieren und die Fohlen bei experimenteller Infektion mit R. equi-Bakterien vor der Erkrankung schützen. Allerdings liegen bisher keine Ergebnisse von Feldstudien über die Wirksamkeit von Lebendimpfstoffen zur Vorbeugung der R. equi-Pneumonie bei Fohlen vor. Schlüsselwörter: Rhodococcus equi / Fohlen / Vorbeugung / Literaturübersicht / Infektiologie / MikrobiologieProphylaxis of Rhodococcus equi pneumonia in foals -a review of literature Rhodococcus equi (R. equi) is a bacterium that causes sporadically and endemically chronic abscess-forming bronchopneumonia in foals under the age of six months. Adult horses in contrast to foals, usually successfully overcome the infection by R. equi. This is due to the effective Th1 immune response, which is more pronounced in adults than in the neonatal period and leads to the destruction of the intracellular pathogens. Attempts to vaccinate mares have actually led to high concentrations of specific antibodies transferred successfully via the colostrum to the foals, but the rate of R. equi pneumonia in foals on endemic farms was not reduced. The administration of specific hyperimmune plasma is not effective for the prevention of R. equi pneumonia either. These disappointing results can be explained by the fact that antibodies alone ...

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“…Observou-se em alguns animais picos de aumento da concentração de linfócitos associados a não mais recuperação da bactéria (Quadro 3). Provavelmente esse aumento de linfócitos contribuiu para promover o "clearence" de Rhodococcus equi do pulmão, já que segundo Hines et al(2001) o "clearance" de R. equi em animais adultos está associado entre outros fatores com um significante aumento de linfócitos CD4+ e CD8+ no fluido do lavado traqueobrônquico. Já nos Potros 6 e 7 as porcentagens de neutrófilos continuaram predominantes, associada a uma constante recuperação bacteriana.…”

Section: Quadro 1 Volumes Recuperados Nas Três Coletas De Lavado Traunclassified

Ureia como marcador de diluição em amostras de lavado traqueobrônquico de potros com rodococose

et al. 2010

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No estudo das infecções e dos mecanismos inflamatórios do trato respiratório posterior, a diluição desconhecida de amostras de lavados traqueobrônquicos leva a um grave problema na interpretação das concentrações de várias substâncias. Foi investigada a amplitude da diluição em uma situação clínica verdadeira, com o objetivo de determinar a validez do uso da dosagem da ureia em lavados traqueobrônquicos para correção da diluição. As amostras do estudo consistiram em lavados traqueobrônquicos obtidos de sete potros com infecção por Rhodococcus equi. Foi realizada a contagem celular total e diferencial e comprado com o quadro clínico e a recuperação bacteriana de todas as amostras. Os fatores de diluição dos lavados variaram entre 14,3 e 130 (média 59,7). O uso da ureia como marcador de diluição melhorou a exatidão na determinação da concentração total de células nos lavados. Estes resultados sugerem que a prática de mensurar substâncias em lavado traqueobrônquico sem correção da diluição possa induzir a falsas conclusões.

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Immunity to Rhodococcus equi: antigen-specific recall responses in the lungs of adult horses

Cited by 49 publications

References 25 publications

Rhodococcus equi

Rhodococcus equi

Prophylaxis of Rhodococcus equi pneumonia in foals – a review of literature

Ureia como marcador de diluição em amostras de lavado traqueobrônquico de potros com rodococose

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