Immune Responses to Mycoplasma Conjunctivae in Alpine Ibex, Alpine Chamois, and Domestic Sheep in Switzerland

Abstract

The humoral immune response of three alpine chamois (Rupicapra rupicapra rupicapra), two alpine ibex (Capra ibex ibex) and three domestic sheep naturally affected with infectious keratoconjunctivitis (IKC), and four ibex and two sheep experimentally infected with Mycoplasma conjunctivae was analysed. In addition, the local immune response to M. conjunctivae was analysed using conjunctival washes from chamois and sheep. Immunoblot analysis of sera using whole cell antigens of M. conjunctivae revealed the major immunogenic proteins which had molecular masses of 175, 83, 68, 60, 50, 42, 36, and 33 kDa. Major antigens were found at 83, 68, 60, and 42 kDa in both sera and conjunctival washes from naturally infected animals of all three Caprinae species. In experimentally infected animals, antibodies to the 68 and 60 kDa antigens were dominant. Naturally infected animals showed much stronger immune reactions than those experimentally infected, and specific antibodies appeared 2 to 4 wk after experimental infection. To evaluate possible cross-reactions, whole cell antigen of M. conjunctivae was analysed by immunoblot against hyperimmune sera of closely related Mycoplasma spp. Antibodies to the 175, 73, 68, 60, and 33 kDa antigens appeared to be specific to M. conjunctivae. Cross-reactions mainly with 83, 50, and 42 kDa antigens were detected, in particular with M. ovipneumoniae and M. bovoculi hyperimmune sera, but also with antisera against M. capricolum capricolum and M. putrefaciens.

Molecular and Antigenic Characterization of aMycoplasma BovisStrain Causing an Outbreak of Infectious Keratoconjunctivitis

“…mycoides SC is the causative agent of contagious bovine pleuropneumonia 21,36 ; other Mycoplasma species are associated with the bovine respiratory tract, both as normal flora (e.g., M. bovirhinis, M. bovoculi, M. arginini, M. canadense, M. alkalescens, and M. bovigenitalium) or as pathogens in diseased calves (M. dispar). 48 Mycoplasma bovoculi and Mycoplasma conjunctivae have been reported to cause conjunctivitis and play an important role in infectious bovine keratoconjunctivitis (IKC) 8,20,27,42 ; M. bovigenitalium, Mycoplasma californicum, M. canadense, M. arginini, and M. bovirhinis are often associated with mastitis. 11,48 Mycoplasma bovis is a major and often overlooked cause of bovine pneumonia, 10 mastitis, 6 and arthritis 33 and has also been reported to cause diseases of the From Istituto di Patologia Speciale e Clinica Medica Veterinaria, Università degli Studi di Sassari, 07100 Sassari, Italy (Alberto, Filippa, Bernardo, Tiziana, Marco), the Center for Biotechnology Development and Biodiversity Research, Università degli Studi di Sassari, 07100 Sassari, Italy (Alberto, Filippa, Marco), Dipartimento di Produzioni Animali, Epidemiologia ed Ecologia, Università degli Studi di Torino, Grugliasco (TO), Italy (Margherita, Sergio), and Istituto Zooprofilattico Sperimentale della Sardegna, Oristano, Italy (Angelo).…”

Detection of specific Mycoplasma conjunctivae antibodies in the sera of sheep with infectious keratoconjunctivitis

“…bovoculi have been reported [5]. Based on the immunoblot analysis of full antigen preparations of M. conjunctivae we have shown in this work that these cross reactions are mainly due to cross-reacting antigens of 83 kDa and 42 kDa of M. conjunctivae which react with anti-M. ovipneumoniae hyperimmune antiserum and with serum from sheep which were seropositive for M. ovipneumoniae.…”

“…These similarities lead to strong serological cross reactions which often hinder an accurate serological diagnosis of the infection. Infection of domestic sheep and wild caprinae with M. conjunctivae was shown to induce a strong humoral response which can be detected by immunoblot analysis through the presence of seroreactive proteins of molecular masses of 175, 83, 68, 60, 50, 42, 36 and 33 kDa [5,9]. However, serological cross reactions between M. conjunctivae and M. ovipneumoniae and Mycoplasma …”

“…However, this method is cumbersome and requires specialised technical experience. Recently, a PCR method based on the 16 S rRNA gene, for the detection and identification of the agent from clinical material was described as well as a Western blot technique for the detection of M. conjunctivae antibodies in infected animals [5,7]. In contrast, no method is available for the rapid detection of specific M. conjunctivae antibodies in sera.…”

“…This is particularly important in the context of M. ovipneumoniae which is very often isolated from sheep with respiratory disease [4] and which is phenotypically and antigenetically the most closely related mycoplasma species to M. conjunctivae [5,15]. The hypothesis was made that the sheep population was acting as a reservoir of M. conjunctivae infections in Switzerland [8], but this role is still unproved.…”