Zebrafish Health & Husbandry: ILAR Journal 2012 Flashcards
Which of the following fields of research was the first one to expand when using zebrafish models as part of an integrative approach to improve human health:
a. Toxicology b. Aging c. Oncology d. Developmental genetics
d. Developmental genetics
Which of the following agents is the most common cause of Microsporidiosis in laboratory zebrafish:
a. Pseudoloma neurophilia b. Pseudocapillaria tomentosa c. Schistocephalus solidus d. Pleistophora hyphessobryconis
a. Pseudoloma neurophilia
Which of the following Mycobacteria has been found to cause severe outbreaks of Mycobacteriosis in laboratory zebrafish:
a. M. fortuitum b. M. chelonae c. M. haemophilium d. M. ulcerans
c. M. haemophilium
Which of the following wild-type strains was the one used for the sequencing and mapping of the zebrafish genome:
a. AB b. SAT c. TL d. SJA
b. SAT
Name the two most common infections found in zebrafish submitted to the ZIRC diagnostic laboratory
Pseudoloma neurophilia (74%)
Mycobacterium spp. (43%)
Which species of mycobacteria is of particular concern because it infects humans?
a. M. fortuitum
b. M. haemophilum
c. M. chelonae
d. M. marinum
d. M. marinum
True or False: Acid fast staining is the primary technique recommended by the Zebrafish International Resource Center for routine surveillance.
True
True or False: The ability of piscine mycobacteria to persist in surface biofilms is not one of the challenges in eliminating infection.
False
Mycobacterium are facultative pathogens that can survive outside the host on biofilms. Screening animals & eggs alone may be ineffective at elimnating the infection.
Which of the following is the currently recommended treatment for elimination of mycobacteria from a facility once it has been established?
a. Vaccination with extracellular mycobacterial products
b. Depopulation
c. Vaccination with attenuated mycobacteria
d. Rifampicin
b.Depopulation
T/F: Mycobacteriosis in fishes is attributable to 3 species of mycobacteria: M. chelonae, M. fortuitum, & M. marinum
False: using more refined diagnostic methods, at least 16 mycobacterium species have been in fish
In zebrafish, at least 6 have been described
Which of the following are clinical signs of mycobacteriosis in zebrafish?
- Non-specific dermal lesions
- Raised scales
- Swollen abdomen
- Emaciation
- No clinical signs
- Erratic swimming
Clinical signs of mycobacteriosis are broad ranging, so any of the listed clinical signs are possible
ID male and female zebrafish
The male is smaller & more stream-liined
The female is larger with a distented abdomen
T/F: Mycobacteria have been observed in the ovaries of zebrafish, suggesting the potential for contamination of off-spring, if not vertical transmission
True
What is considered to be the primary route of transmission of mycobacteria in fish?
Ingestion: the intestine is likely the primary route of invasion
This highlights the importance of removing dead and moribund fish as soon as possible
Which of the following species of mycobacterium is of particular concern regarding zoonotic disease.
- M. chelonae
- M. fortuitum
- M. marinum
- M. haemophilum
M. marinum
It is known to infect humans
Direct transmission from fish has not been confirmed, but is strongly suspected
What is thought to limit the establishment and spread of fish-associated mycobacterial infections in humans?
Human core body temperature
Fish-associated mycobacteria do not grow well at 37ºC
Name two acid fast stains that can be used to ID mycobacteria in histologic sections.
Ziehl-Neelsen
Fite’s
Describe culture conditions used for mycobacteria
Middlebrook 7H10 agar supplemented with oleic acid, albumin, dextrose & catalase
Or growth on Lowenstein-Jensen Slants
Cultures are incubated at 28-30ºC and monitored for 6-8 weeks
Which of the following is considered the gold-standard for a thorough investigation and subsequent storage and cataloguing of mycobacterial species and strains?
- Acid fast staining of histo sections
- PCR detection & sequencing
- Culture
Culture
PCR detection & sequencing are useful to ID mycobacterial species, but not strains
T/F: Different strains of a given species of mycobacterium will develop their own unique properties & challenges.
True
Which of the following mycobacteria are associated with low-level chronic disease? Which are associated with higher virulence, disseminated infections, & higher levels of mortality?
- M. marinum
- M. chelonae
- M. abscessus
- M. fortuitum
- M. haemophilum
- M. peregrinum
M. marinum & M. haemophilum are associated with a higher level of virulence, disseminated infections & higher mortality rates
The others are associated with low-level chronic disease
T/F: Environmental conditions & the nutritional and immunological state of zebrafish are probably the most important variables affecting the pathogenesis of mycobacteriosis.
True
While different species & strains of mycobacterium have different effects, the overall health of the zebrafish affects the course of disease the most
T/F: All lines of zebrafish appear equally susceptible to mycobacterial infection
False
Different lines of zebrafish appear to be more or less susceptible to infection based on a cross-sectional study at a single facility (2 references listed)
Name the three tissues most likely to harbor mycobacterial granulomas in zebrafish.
Liver, kidney, spleen
T/F: In the aquatic environment, biofilms are found on all surfaces, and this biofilm and the detritus at the bottom of the tank are thought to be the source of mycobacterial infection.
True
T/F: The efficacy of the standard practice of bleaching eggs for 10 minutes at 50ppm is well established.
False
Various studies have evaluated the efficacy of bleach solutions on mycobacterial cultures exist, but no evidence regarding the efficacy of bleach myocbacteria in biofilms or on eggs exists.
Bacteria harbored within eggs are protected from disinfectants & present a risk to other eggs
T/F: The life cycle of Microsporidia consists of two general developmental stages: merogony and sporogony
True
Meronts multiply within the infected host cell, eventually forming sporonts and then spores, which are ultimately released from the host cell and transmit the infection.
T/F: Microsporidia are generally susceptible to many standard forms of surface decontamination used for fish eggs, such as chlorine and iodophores.
False.
The infectious spore stage has a thick, chitinous endospore making it extremely resistant to environmental stress and lysis.
T/F: Spores of P. neurophilia relesed from aggregates in myocytes or peripheral nerves in the somatic muscle typically elicit a severe inflammatory reaction.
True
T/F: Spores of P. hyphessobryconis can also be observed in the kidney, spleen, intestine and ovaries in heavier infections.
True
T/F: PCR-based assays are recommended for the specific detection of P. hyphessobryconis.
False.
No PCR-based assays currently exist for the specific detection of this parasite
T/F: the cryopreservation of zebrafish sperm prevents the spread of microsporidians.
False.
Microsporidians have the ability to survive during cryopreservation.
T/F: Pseudoloma neurophilia is the most common pathogen detected in zebrafish
True
Detected in 74% of the facilities examined by the ZIRC diagnostic service in 2010
What does ZIRC stand for?
- Zebrafish International Research Consortium
- Zebrafish Institute Research Center
- Zebrafish International Resource Center
- Zebrafish International Research Consortium
Zebrafish International Resource Center
Which of the following are clinical signs of Pseudoloma neurophila infection in zebrafish?
- Emaciation
- Lordosis
- Scoliosis
- No clinical signs
- Reduced fecundity
Infection produces a wide range of clinical signs & any of the listed signs are possible
Which of the following is a muscle-infecting microsporidium that has been described in laboratory populations of zebrafish?
- Paracheirodon innesi
- Pleistophora hyphessobryconis
- Danio nigrofasciatus
- Encephalitozoon cuniculi
Pleistophora hyphessobryconis
The following histology was obtained from a fish with emaciation and scoliosis…what is the diagnosis?
Pseudoloma neurophilia - microsporidiosis
A. Low magnification showing inflammation in skeletal muscle. Bar = 100 µm. Inset at upper left shows macrophage with 4 spores
B-D. Spores (arrows) in eggs. B) H&E. C) Acid fast, spores fill a degenerate egg, D) Gram, showing blue-staining spores.
E. Spores in spinal cord stain blue with the tissue Gram stain.
T/F: Microsporidian spores can often be seen in wet mounts from infected tissues and are discernible by their generally refractile appearance and characteristic posterior vacuole.
True
This is a wet-mount and geimsa stained tissue prepared from the brain & spinal cord of a zebrafish at necropsy. What is the diagnosis?
Microsporidiosis - Pseudoloma neurophilia
Pseudoloma from brain.
A. Giemsa stain
B. Wet mount with Nomarski’s phase interference
Bar = 10 µm.
What additional stain requiring fluorescence microscopy can be used to increase sensitivity of microsporidian spore detection by histology. An image below represents this stain.
Chitin-specific Fungi-Fluor stain
A. Low magnification showing numerous spores (stained blue with DAPI filter) in spinal cord xenomas (arrow).
B. High magnification of spores (S) in ovaries.
In which of the following tissues may large aggregates of P. neurophilia spores be seen?
- Neural tissue of the posterior brain & spinal cord
- Kidney
- Skeletal muscle
- Gut epithelium
- Ovary
Large aggregates are typically found in neural tissue of the posterior brain & spnal cord
Smaller groups or individual spores can be seen in the other tissues listed
What molecular diagnostic techiques are available for detecting P. neurophilia?
Convential & real-time PCR targeting the small subunit of the ribosomal DNA gene are available
T/F: Microsporidia are spread through direct transmission through ingestion of spores and infected tissue in the water
True
T/F: Zebrafish frequently spawn spontaneously in aquaria, and hence release of eggs, ovarian fluids, and tissues at spawning provides an important potential route of horizontal transmission.
True
T/F: Maternal transmission has not been reported for microsporidans in fish
False
Vertical transmission of microsporidans have been documented in fish
Experimental & observational lines of evidence suggest that maternal transmission of P. neurophilia, either transovarial or transova, does occur
Which of the following is considered the best method for routine health monitoring of zebrafish?
- Serologic testing
- PCR
- Culture
- Histopath
Histopathologic analysis is the best overall method for routine health monitoring of zebrafish because of the ability to assess all tissues and to detect novel pathogens, which would not be detected by PCR. Serologic testing is not available for zebrafish.
T/F: Exposing a population of known uninfected fish to the untreated effluent from other tanks on the system allows facility managers to assess the infection status of fish in the system on a large scale
True
Also…exposing sentinels to treated effluent can be used to assess the decontamination efficacy of the system.
What is the recommended quarantine procedure for introducing new fish into a facility?
Bring adults into quarantine, spawn them, and then move only the progeny of those adults that are screened and determined to be microsporidian-free into the main facility.
Which of the following doses of UV sterilization has been shown to be effective in the inactivation of microsporidian parasites of human concern?
- 1 mJ/cm sq
- 6 mJ/cm sq
- 30 mJ/cm sq
- 100 mJ/cm sq
6 mJ/cm sq
What is the generally recommended method of disinfecting zebrafish eggs with bleach?
Is this effective at killing P. neurophilia?
Bath treatment with 25-50 ppm bleach for 10 minutes
No, it is not effective at killing P. neurophilia & probably not mycobacterium
T/F: Microsporidian spores are highly resistant to current methods of surface sterilization of eggs, and these methods cannot be relied upon to eliminate P. neurophilia or other microsporidia from a population
True
T/F: Current molecular diagnostic methods can easily be applied to the testing of eggs, sperm, and larval fish. These methods have been used to establish P. neurophilia SPF colonies of zebrafish
True
What level of chlorine is required to kill >95% of P. neurophilia spores?
- 5 ppm, pH 7
- 5 ppm, pH 8
- 100 ppm, pH 7
- 100 ppm, pH 8
100 ppm, pH 8
Efficacy of chlorine is pH dependent
This dose is lethal for embryos