Molecular and immunohistochemical diagnosis of Francisella noatunensis subsp. orientalis from formalin-fixed, paraffin-embedded tissues

Abstract

Abstract. Members of the genus Francisella (viz., F. noatunensis subsp. orientalis [Fno] and F. noatunensis subsp. noatunensis) have been described as causative agents of chronic granulomatous and pyogranulomatous lesions in wild and cultured fish species. In the present study, 68 archived formalin-fixed, paraffin-embedded (FFPE) tissues from several fish species, collected at different geographical locations from 2000 to 2011, were analyzed using a real-time polymerase chain reaction assay for the detection of the Fno intracellular growth loci C (iglC) gene and by immunohistochemistry for the demonstration of Fno antigens. The results revealed a high correlation between these 2 diagnostic techniques validating their use for the diagnosis of Fno infection in archived FFPE tissues and confirming the presence of Fno in fish species from the Caribbean, Hawaii, and continental North and South America in the early years of the present century.

Francisella noatunensis subsp. orientalis infects striped catfish (Pangasianodon hypophthalmus) and common carp (Cyprinus carpio) but does not kill the hosts

“…The result obtained in the current study was consistent with previous publications that Nile tilapia and red tilapia were gravely vulnerable to Fno infection (Nguyen et al, 2015;Soto et al, 2013). Apart from tilapia, other fish species such as three-lined grunt (Kamaishi et al, 2005), hybrid striped bass (Ostland et al, 2006), 11 species of ornamental cichlids (Hsieh et al, 2007), Chinese catfish and barramundi (Soto et al, 2012) have also been reported as naturally infected hosts of Fno.…”

Molecular detection of Francisella noatunensis subsp. orientalis in cultured Nile tilapia (Oreochromis niloticus L.) in three Brazilian states

“…orientalis ( Fno ), characterized by systemic granulomatous infection and high mortality rates, is regarded as one of the most important diseases of cultured tilapia worldwide, particularly in temperate regions, where temperatures drop below 25 °C (Colquhoun & Duodu ; Soto et al . ).…”

“…At present, intensive fish production systems and their high stocking densities are a driving force in the establishment and dissemination of emergent infectious diseases, including piscine francisellosis (Birkbeck, Feist & Verner-Jeffreys 2011 (Colquhoun & Duodu 2011;Soto et al 2012a).…”

Outbreaks and genetic diversity of Francisella noatunensis subsp orientalis isolated from farm-raised Nile tilapia (Oreochromis niloticus) in Brazil

“…Francisella asiatica), have been shown to be associated with francisellosis in the chicken grunt (Parapristipoma trilineatum), hybrid striped bass (Morone saxatilis x M. chrysops), Atlantic salmon (Salmo salar), Atlantic cod (Gadus morhua), tilapia (Oreochromis spp), ornamental cichlid, and damselfish (Chromis viridis) (Hsieh et al, 2007;Birkbeck et al, 2011;Camus et al, 2013). Francisellosis primarily affects the fry and fingerling stages of fish, which exhibit systemic granulomatosis with multifocal granulomas in the internal organs, including the liver, spleen, and kidney (Soto et al, 2009(Soto et al, , 2012a.…”