Mouse Model of Respiratory Tract Infection Induced by Waddlia chondrophila

Abstract

Waddlia chondrophila, an obligate intracellular bacterium belonging to the Chlamydiales order, is considered as an emerging pathogen. Some clinical studies highlighted a possible role of W. chondrophila in bronchiolitis, pneumonia and miscarriage. This pathogenic potential is further supported by the ability of W. chondrophila to infect and replicate within human pneumocytes, macrophages and endometrial cells. Considering that W. chondrophila might be a causative agent of respiratory tract infection, we developed a mouse model of respiratory tract infection to get insight into the pathogenesis of W. chondrophila. Following intranasal inoculation of 2 x 108 W. chondrophila, mice lost up to 40% of their body weight, and succumbed rapidly from infection with a death rate reaching 50% at day 4 post-inoculation. Bacterial loads, estimated by qPCR, increased from day 0 to day 3 post-infection and decreased thereafter in surviving mice. Bacterial growth was confirmed by detecting dividing bacteria using electron microscopy, and living bacteria were isolated from lungs 14 days post-infection. Immunohistochemistry and histopathology of infected lungs revealed the presence of bacteria associated with pneumonia characterized by an important multifocal inflammation. The high inflammatory score in the lungs was associated with the presence of pro-inflammatory cytokines in both serum and lungs at day 3 post-infection. This animal model supports the role of W. chondrophila as an agent of respiratory tract infection, and will help understanding the pathogenesis of this strict intracellular bacterium.

Chlamydia-Like Organisms (CLOs) in Finnish Ixodes ricinus Ticks and Human Skin

“…A variety of CLOs have been detected in various environmental (water and soil) samples, in amoebae and in animals, such as bats, deer, seabirds, snakes, arthropods, isopods and fish [ 2 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. The role of CLOs as human pathogens is currently being explored: Recent publications have reported association between Waddlia chondrophila and tubal factor infertility [ 11 ], adverse pregnancy outcome [ 12 ] and lower respiratory tract infections [ 13 ]; Simkania negevensis and Rhabdochlamydia spp. may be associated with respiratory infections [ 14 , 15 , 16 ], and Parachlamydia acanthamoebae with pneumonia [ 17 , 18 , 19 ].…”

Culture‐independent genomics of a novel chlamydial pathogen of fish provides new insight into host‐specific adaptations utilized by these intracellular bacteria

“…Molecular and sero‐ epidemiological surveys have detected CRBs in association with respiratory disease in humans (Kahane et al ., ; Friedman et al ., ) and livestock (Wheelhouse et al ., ) and reproductive disease in both humans and animals (Borel et al ., ; Baud et al ., ; Barkallah et al ., ). Further, murine respiratory disease models have recently been established for Waddlia chondrophila (Pilloux et al ., ) and Parachlamydia acanthamoebae (Casson et al ., ), as has a bovine model of P. acanthamoebae respiratory disease (Lohr et al ., ) and a murine model of W. chondrophila genital infection (Vasilevsky et al ., ), confirming Koch's postulates for these causative agents of disease. Questions nevertheless remain about whether these organisms are truly pathogens of their varied host species.…”

Sex-dependent vulnerability for Wistar rats model following intranasal instillation with Klebsiella pneumoniae ATCC 43816 causing lobar pneumonia.

“…It is an opportunistic pathogen causing both community-acquired and nosocomial infections [20], ranging from mild urinary tract infections to severe pneumonia with high morbidity and mortality rates [21][22][23]. Various studies have investigated the role of gender on the infectivity of K. pneumoniae or other pneumonic pathogens on animal models of pneumonia, such as mice (Swiss albino, C57BL/6, BALB/c, NMRI, DBA/2, Swiss Webster, etc) and Sprague Dawley rats [2,8,14,24,25].…”