Biosecurity

Question 1

What is the most dependable approach for eliminating infections with unrecognized and known pathogens?

Answer 1

Rederivation

Question 2

What has fostering Cesarian-section derived pups onto gnoto or SPF dams largely been replaced by?

Answer 2

Embryo transfer into pseudopregnant females.

Question 3

How does embryo transfer protect against vertical transmission?

Answer 3

Zona pellucida surrounding embryo and oocytes excludes pathogens. Risk of infecting recipient females minimized by washing of embryos.
Vertical transmission has been demonstrated for viruses and bacteria capable of colonizing the uterus.

Question 4

How does neonatal transfer of pups work?

Answer 4

Within several days of parturition. Pups transferred to SPF dams after being immersed in a disinfectant. Does not require euthanasia of dam.

Question 5

Can fostering be cross-species?

Answer 5

Yes. Gerbils onto rats and mice, with gerbil pup survival higher for those weaned onto mice.

Question 6

How are pinworm and mite infestations typically treated?

Answer 6

Chemotherapy - Avermectins and benzimidazoles. Risk of toxicity from crossing BBB in young, genetic background, or GEM.

Question 7

For which agents has antibiotic treatment been efficacious?

Answer 7

P. pneumotropica and H. hepaticus. They do not survive long ex vivo and are unlikely to infect host after treatment is stopped.

Question 8

Burnout is historically applied to what type of agents? Is burnout recommended?

Answer 8

Nonpersistent infections of immunocompetent hosts with enveloped viruses. Sendai, SDAV
Not recommended due to increasing number of genetically modified rodents and unknown immune competence and atypical response to infection.

Question 9

Why is MNV not susceptible to burnout?

Answer 9

Shed indefinitely

Question 10

What is the principal reservoirs of adventitious infection for SPF animals?

Answer 10

Infected animals of the same or related species.

Question 11

Which agent is notable exception to most pathogens being efficiently transmitted via direct contact?

Answer 11

Lactate dehydrogenase-elevating virus (LDV)

Question 12

Generally, what type of pathogens do not transmit well in soiled bedding?

Answer 12

Host-adapted bacteria, enveloped viruses, and organisms that are unstable ex vivo.

Question 13

Diet has been linked to outbreaks of what pathogens? (2) How can this be reduced?

Answer 13

MPV and mouse rotavirus
Gamma irradiation of diets

Question 14

What the erythrocyte parasites of mice and rats?

Answer 14

M: Eperythrozoon coccoides
R: Mycoplasma haemofelis

Question 15

What agents are generally resistant to inactivation?

Answer 15

Bacterial spores, free-living stages of parasites (pinworm eggs and protozoan cysts), and hydrophilic nonenveloped viruses.

Question 16

What are two physical processes for disinfection?

Answer 16

Autoclaving and electromagnetic irradiation

Question 17

What temps are foods heated to during pelleting? What does this result in?

Answer 17

Heated to 75-80C. Substantially reduces bacterial count but not sufficient to inactivate thermostable pathogens.

Question 18

Why is gamma irradiation of diets preferred to autoclave?

Answer 18

Autoclaving causes a greater reduction in nutritional content of feed. Also difficult to achieve uniform steam penetration and temperature throughout a load.

Question 19

How is gamma radiation typically emitted? What does this create at the microscopic level?

Answer 19

From a cobalt-60 source. Creates breakages in the nuclei acid of microorganisms.

Question 20

What wavelengths is UV? Where on the spectrum is the peak of UV bactericidal activity? How does UV function in inactivation?

Answer 20

UV = 210-328 nm. Bactericidal activity is maximal near peak of DNA absorption at 260 nm.
UV does not have sufficient energy to cause ionization. Damages DNA but does not cause DNA breaks. Instead, produces thiamine and other pyrimidine dimers.

Question 21

How does UV and gamma radiation interact with solid objects?

Answer 21

Gamma radiation passes through solid objects, UV does not. UV only for disinfection of surfaces and drinking water.

Question 22

What factors reduce the efficacy of UV sterilization of water?

Answer 22

Intensity of UV source, cleanliness of source, and particles or dissolved organics in water.

Question 23

Why is UV irradiation an attractive option for water disinfection?

Answer 23

Viricidal. In contrast to chlorination, does not convert organic precursors into potentially carcinogenic trihalomethanes.

Question 24

Generally, what is the radiosensitivity of organisms related to? What are examples of resistant agents?

Answer 24

Correlates with genome volume and ability of an organism to repair DNA damage. Small viruses, such as parvoviruses, bacterial spores, protozoan cysts, and vegetative bacteria with highly efficient DNA repair capabilities are resistant.

Question 25

Describe depth versus membrane filters.

Answer 25

Depth filters entrap and adsorb, membrane filters exclude particles according to pore site. Depth filters have no meaningful pore size, and thus are given nominal ratings to indicate the efficiency with which they retain particles of a particular size.

Question 26

What are the three classifications of filtration size? What can each catch?

Answer 26

Microfiltration = 0.1-10 um Ultrafiltration = 1k - 1000k molecular weight Reverse osmosis = low molecular weight molecules, including salts. Microfiltration retains bacteria, fungi, and their spores, but only ultrafiltration or RO can remove viruses.

Question 27

What are the characteristics of waterborne viruses?

Answer 27

Small to medium sizes, nonenveloped, and shed in feces.

Question 28

How do denaturants, reactants, and oxidants act?

Answer 28

Denaturants - Disrupt protein or lipid structures Reactants - Form or break covalent bonds Oxidants.

Question 29

What class of chemical disinfectants are most commonly used? Why? What are examples?

Answer 29

Oxidants, as they are generally considered more effective than reactants and denaturants for inactivating resistant pathogens such as spore-forming bacteria, nonenveloped viruses, and free-living forms of parasites.

Question 30

Question 31

Question 32

Question 33

Can disinfectants be layered?

Answer 33

Yes, especially when disinfection requirements are especially strict.

Question 34

What agents are phenolics and quarternary ammonium compounds effective against?

Answer 34

Lipophilic, enveloped viruses

Question 35

What agents are oxidants effective against?

Answer 35

All organic compounds, inactivating hydrophilic and lipophilic viruses

Question 36

How does pH and temperature affect chlorine's function?

Answer 36

Increasing the pH or temp of the water reduces chlorine concentration of hypochlorous acid in favor of hypochlorite ion, which is less biocidal

Question 37

Where do the majority of mycoplasma found in cell culture originate from?

Answer 37

Human, porcine, and bovine origin.