Transmission ofPseudoloma neurophiliain Laboratory Zebrafish (Danio rerio) When Using Mass Spawning Chambers and Recommendations for Chamber Disinfection

Abstract

Pseudoloma neurophilia, a microsporidium that primarily infects neural tissues, is a common pathogen in laboratory zebrafish. The risk of parasite transmission with different spawning apparatuses and the effectiveness of disinfection are unknown. In this study, we spawned uninfected zebrafish with P. neurophilia-infected zebrafish in either 50 L mass spawning chambers (MSCs) or 1 L standard breeding tanks (BTs). Fish were spawned once or thrice, with and without chamber disinfection between uses, to evaluate risk of vertical and horizontal transmission. Six disinfection protocols were tested to determine which effectively eliminated residual spores. We demonstrated that three consecutive uses of an MSC significantly increased the risk of transmission to other fish when compared to the use of BTs or only one spawning event in an MSC (both p < 0.0001). Vertical transmission was not detected with any method. Disinfection with ∼100 ppm bleach soak (pH ∼7.0), 75 ppm Wescodyne soak, and 175 ppm Wescodyne Plus spray was 100% effective in eliminating spores from the MSCs. Disinfection of MSCs before spawning did not decrease P. neurophilia transmission when infected fish remained present in the breeding population. Researchers should avoid using endemically infected fish in MSCs to minimize transmission of pathogens within their colonies.

Reviewing Pseudoloma neurophilia infections in the popular zebrafish model

“…Wastewater is filtered by a particulate bead filter, a fluidized biofilter and a 10-µm bag filter, and then, water is passed through biological UV treatment (100,000 µWs cm -2 ) before being returned to aquaria (Kent et al 2011). Post-filtration UV sterilizers have been also described as useful against other species of taxonomic division microsporidian (Peneyra et al 2018).…”

“…Diseases caused by P. neurophilia infection in zebrafish can have a wide spectrum of symptomatology, from benign effects to emaciation, skeletal deformities and even death (Peneyra et al 2018;Sanders et al 2020). Nevertheless, many infected fish are asymptomatic, in particular at early stages of infection, thus causing hidden infections that can generate outbreaks and cause serious sanitary problems in the fish facilities.…”

“…(2015a) and Peneyra et al . (2018)). It can be outlined that infection outbreaks may depend on the zebrafish laboratory strain as differences in the occurrence of aggregates and parasite‐associated lesions were observed.…”

“…Only few screening protocols have been developed so far (e.g. those found in Kent et al (2011), Spagnoli et al (2015a) and Peneyra et al (2018)). It can be outlined that infection outbreaks may depend on the zebrafish laboratory strain as differences in the occurrence of aggregates and parasite-associated lesions were observed.…”

The Tagging Procedure of Visible Implant Elastomers Influences Zebrafish Individual and Social Behavior

“…19 This tagging procedure has been repeatedly reported to beget major advantages in terms of feasibility and durability and, in light of its minimal side effects, is becoming a standard in fish experiments. 12,[20][21][22][23][24][25] Notwithstanding its safety, this procedure-developed with the aim of assisting behavioral studies-needs to be systematically assessed to evaluate whether it affects social behavior. 26 The potential confounds introduced by VIE tagging may take different forms, ranging from simple locomotor effects (the implant may interfere with natural patterns of locomotion) 27 to more complex social interactions, where shoal mates may have a differential appraisal of a color-marked individual compared to a naturally colored conspecific.…”