The present invention relates to novel adenovirus strains with a high immunogenicity and no pre-existing immunity in the general human population. The lack of pre-existing immunity is due to novel hypervariable regions in the adenoviral capsid protein hexon. The novel adenovirus strains also have an improved capacity for reproduction. The present invention provides nucleotide and amino acid sequences of these novel adenovirus strains, as well as recombinant viruses, virus-like particles and vectors based on these strains. Further provided are pharmaceutical compositions and medical uses in the therapy or prophylaxis of a disease, and methods for producing an adenovirus or virus-like particles utilizing the novel sequences, recombinant viruses, virus-like particles and vectors.