The immune response against Chlamydia suis genital tract infection partially protects against re-infection

Evelien De Clercq,Eric Cox,Koen Chiers,Lizi Yin,Bert Devriendt,Daisy Vanrompay

doi:10.1186/preaccept-1798426261135375

Evelien De Clercq, Eric Cox + Show 4 more

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https://doi.org/10.1186/preaccept-1798426261135375

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Abstract

The aim of the present study was to reveal the characteristic features of genital Chlamydia suis infection and re-infection in female pigs by studying the immune response, pathological changes, replication of chlamydial bacteria in the genital tract and excretion of viable bacteria. Pigs were intravaginally infected and re-infected with C. suis strain S45, the type strain of this species. We demonstrated that S45 is pathogenic for the female urogenital tract. Chlamydia replication occurred throughout the urogenital tract, causing inflammation and pathology. Furthermore, genital infection elicited both cellular and humoral immune responses. Compared to the primo-infection of pigs with C. suis, re-infection was characterized by less severe macroscopic lesions and less chlamydial elementary bodies and inclusions in the urogenital tract. This indicates the development of a certain level of protection following the initial infection. Protective immunity against re-infection coincided with higher Chlamydia-specific IgG and IgA antibody titers in sera and vaginal secretions, higher proliferative responses of peripheral blood mononuclear cells (PBMC), higher percentages of blood B lymphocytes, monocytes and CD8+ T cells and upregulated production of IFN-γ and IL-10 by PBMC.

Highlights

Chlamydia suis is widespread in commercial pig production and causes important economic losses [1]
In 60% of the pigs of the infection group, a large amount of clear watery exudate was present in almost the entire genital tract (Additional file 1), whereas only one animal (20%) of the re-infection group showed a moderate amount of watery exudate in the cervix
Genital C. suis infections are likely to be transmitted venereally, since these bacteria have been detected in the semen of boars [1,12,13]

Summary

Introduction

Chlamydia suis is widespread in commercial pig production and causes important economic losses [1]. C. suis infections are associated with a variety of diseases including conjunctivitis [2], rhinitis [3], pneumonia [3,4], enteritis [5,6], periparturient dysgalactiae syndrome (PDS) [7] and numerous reproductive disorders [1,7,8,9,10] such as abortion, mummification, perinatal and neonatal mortality, repeat breeding, vaginal discharge and endometritis in addition to orchitis, epididymitis and urethritis in boars [11]. Experimental infection of gnotobiotic and conventionally raised pigs with C. suis proved its pathogenic potential for the porcine respiratory system [3,4,17], gastrointestinal tract [5,6,18] and eyes [2].

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