Preexisting Neutralizing Antibodies to Adeno-Associated Virus Capsids in Large Animals Other Than Monkeys May Confound In Vivo Gene Therapy Studies.

Adeno-associated virus (AAV) vectors are currently being tested not only in small animal models such as mice but also in large animal models, including pigs, dogs, and horses. Natural exposure to AAV occurs in most of the species used in these studies and potentially elicits a neutralizing humoral immune response to AAV. In this study, we show the prevalence of neutralizing antibodies (NAbs) to several AAV serotypes in these large animals as measured by an in vitro NAb assay and the ability of these NAbs to block AAV transduction in an in vivo mouse model of NAb passive transfer assay. The results of this study clearly show the importance of evaluating large animal models for the presence of AAV NAbs before enrolling them in AAV-mediated gene therapy studies.

Effect of the nuclear-donor cell lineage, type, and cell donor on development of somatic cell nuclear transfer embryos in cattle.

Potential applications of somatic cell nuclear transfer to agriculture and medicine are currently constrained by low efficiency and high rates of embryonic, fetal, and neonatal loss. Nuclear transfer efficiency in cattle was compared between three donor-cell treatments from a single animal, between four donor-cell treatments in sequential stages of differentiation from a single cell lineage and genotype, and between the same cell type in two donors. Cumulus and granulosa donor cells resulted in a greater proportion of viable day-7 embryos than ear-skin cells; pregnancy rate and losses were not different among treatments. The least differentiated cell type in the follicular cell lineage, preantral follicle cells, resulted in fewer cloned blastocysts (11%) than cumulus (30%), granulosa (23%), and luteal (25%) donor cells. Cloned blastocysts that did develop from preantral follicle cells (75%) were more likely to progress through implantation into later stages of pregnancy than cloned blastocysts from cumulus (10%), granulosa (9%), and luteal (11%) donor cells (p < 0.05). Day-7 embryo development from granulosa cells was similar between two donors (19 vs. 24%) and proved to be a poor indicator of further development as day-30 pregnancy rates varied threefold between donors (48 vs. 15%, p < 0.05). Results reported here emphasize the crucial role of the nuclear donor cell in the outcome of the nuclear-transfer process.