The invention provides a method of inducing an immune response in a mammal. The method comprises administering to the mammal a non-subgroup C adenoviral vector comprising an adenoviral fiber protein having an amino acid sequence comprising about 80 % or more identity to an amino acid sequence encoding a subgroup C adenoviral fiber protein. The adenoviral vector further comprises a nucleic acid sequence encoding an antigen which is expressed in the mammal to induce an immune response. The invention further comprises a method of producing an adenoviral vector, and a composition comprising a serotype 41 or a serotype 35 adenoviral vector and a carrier. The invention also provides an adenoviral vector comprising a nucleic acid sequence encoding an adenoviral pIX protein operably linked to a heterologous expression control sequence, as well as a method of enhancing the stability and/or packaging capacity of an adenoviral vector.