DNA deaminase (cytidine deaminase) which acts as an inhibitor of retrovirus replication and retrotransposon mobility via deaminase-dependent and -independent mechanisms (By similarity). Selectively targets single-stranded DNA and does not deaminate double-stranded DNA or single- or double-stranded RNA (By similarity). Does not reduce infectivity of foamy feline virus, feline immunodeficiency virus or feline leukemia virus (PubMed:18315870). a 2'-deoxycytidine in single-stranded DNA + H(+) + H2O = a 2'-deoxyuridine in single-stranded DNA + NH4(+) (Microbial infection) Interacts with feline foamy virus protein Bet (PubMed:15911774). This interaction does not induce APOBEC3Ca degradation but prevents its dimerization and incorporation into the virion (Probable). One of 3 related APOBEC3C genes in cat, APOBEC3Ca, APOBEC3Cb and APOBEC3Cc, which are likely to have been generated after two consecutive gene duplications. Potent inhibitor of Bet-deficient foamy feline virus (PubMed:15911774, PubMed:18315870). Does not inhibit Vif-deficient feline immunodeficiency virus (PubMed:18315870). Belongs to the cytidine and deoxycytidylate deaminase family.