Rederivation of Transgenic and Gene-Targeted Mice by Embryo Transfer

Abstract

Research on genetically engineered mice provides insights into the etiology, therapy, and genetic basis of human diseases. An important variable that affects the results of mouse studies is the health status of the animals. Pathogen burdens may confound observations and obscure underlying mechanisms. Mouse resource centers frequently rederive infected mouse strains. We review our experience on the use of a well-established technique, embryo transfer to rederive infected mouse strains. The following mouse pathogens were eliminated by embryo transfer: Mouse Parvovirus, Mouse Hepatitis Virus, Mouse Rotavirus, Mouse Encephalomyelitis Virus, Mouse Adenovirus, Helicobacter species, endoparasites, and ectoparasites. We rederived transgenic mouse lines, gene-targeted mouse lines, and lines with spontaneous mutations. In the majority of strains, fertilized eggs for embryo transfer were obtained by mating superovulated egg donors with males of the desired genotype. A total of 309 embryo transfers were performed to rederive 96 mouse strains. The pregnancy rate was 76%; 1996 pups were born, of which 43% carried the desired genotype. We performed 44 additional embryo transfers to rederive 15 other strains. The pregnancy rate was lower (45%) and none of the 135 pups carried the desired genotype. Although we successfully eliminated the pathogens in all transfers, we were unable to obtain pups with the desired genotype in 15 of 111 mouse lines. Multiple factors affect the efficiency of rederivation by embryo transfer. They include the response to superovulation by embryo donors, the number and age of stud males, the yield of fertilized eggs, the number of embryo transfers, and genotyping.

New Building, Old Parasite: Mesostigmatid Mites--An Ever-Present Threat to Barrier Rodent Facilities

“…Regular health surveillance (Livingston 2003) helps to detect excluded organisms, and should there be an outbreak, mites and pinworms are variously susceptible to treatment with parasiticides such as avermectins, pyrethroids, and benzimidazoles (Baumans et al 1988;Bean-Knudsen et al 1986;Bornstein et al 2006;Coghlan et al 1993;Flynn et al 1989;Hill et al 2005Hill et al , 2006Huerkamp et al 2000Huerkamp et al , 2004Huerkamp et al , 2005Klement et al 1996;Pullium et al 2005;Santora et al 2002;Sueta et al 2002). Also in the event of an outbreak, the rederivation of valuable genetic lines is possible through embryo transfer (Baker 1988;Reetz et al 1988;Van Keuren and Saunders 2004), cesarean rederivation (Nagy et al 2003), and neonatal transfer (Hickman and Thompson 2004;Huerkamp et al 2005;Singletary et al 2003;Truett et al 2000;Watson et al 2005).…”

Risk Assessment of Mouse Hepatitis Virus Infection via In Vitro Fertilization and Embryo Transfer by the Use of Zona-Intact and Laser-Microdissected Oocytes1

“…Due to the fact that subclinical infections can have an impact on the physiological reaction of mice under experimental conditions, the demand for such animals in current research is rapidly increasing. Specific pathogen-free (SPF) mice are generally obtained by hysterectomy or by embryo transfer [3][4][5][6][7]. Additionally, embryo transfer is a well-established procedure used to recover in vivoand in vitro-produced embryos stored in frozen embryo banks [8] or for recovery of frozen sperm samples [9,10].…”

Prevalence of Helicobacter hepaticus, Murine Norovirus, and Pneumocystis carinii and Eradication Efficacy of Cross-Fostering in Genetically Engineered Mice

“…To eradicate these pathogens, various methods have been used such as antibiotic therapy, embryo transfer, Caesarean section, and cross-fostering. In most studies, embryo transfer has shown the highest efficacy for rederivation [30], and Caesarean section can be successful for eradication of pathogens if there is no transplacental transmission. However, these surgical methods are expensive and time-consuming.…”