Which virus can be eliminated from a colony by embryo rederivation?

• A. Bacteriophage
• B. Mouse parvovirus
• C. Mouse hepatitis virus
• D. Minute virus of mice

Answer: (C)

Embryo rederivation works by removing an infected dam from the equation and producing offspring from embryos that are transferred into pathogen-free surrogate mothers. The pups then develop in a virus-free environment, so infections that were carried by the dam or acquired around birth are not passed on to the new colony. Mouse hepatitis virus is particularly susceptible to this approach because it is primarily spread through contact and secretions after birth and does not persist in the embryo itself. By deriving from clean embryos and rearing in a clean facility, the offspring become free of the virus.

Bacteriophages are viruses of bacteria and not pathogens that propagate in the mammalian host, so they aren’t addressed by this method. Parvoviruses like mouse parvovirus and minute virus of mice can be challenging to eradicate with embryo rederivation because they can persist in tissues or be associated with the germline, making complete removal less reliable.