**13. Adenovirus vectors vaccines**

Adenovirus vectors first appear in the 1980s. They have received great attention as gene delivery systems for vaccine antigens and were extensively tested in several preclinical and clinical studies. Adenovirus-based vector vaccines have been developed and are being studied against a variety of infectious diseases, including influenza, measles, hepatitis B, rabies, anthrax, Ebola, severe acute respiratory syndrome (SARS), human immunodeficiency virus 1 (HIV-1), malaria, tuberculosis [36–40]. A study of an oral tableted vaccine based on a nonreplicative recombinant adenovirus-5 serotype carries DNA that encodes the hemagglutinin of A/California/04/2009 (H1N1) pdm with an adjuvant added in the form of double-stranded RNA (dsRNA) [41] showed that after a single immunization, significant systemic and local immunity occurs. Seroconversions of anti-hemagglutinating antibodies to A/H1N1 pandemic influenza viruses were detected in 92% of participants [41].

The advantages of adenoviral vectors are that they efficiently transfer genes to both dividing and nondividing cells, do not integrate into the genome, and provide high titers of recombinant virus and high expression levels of the introduced genes. Although currently used adenoviral vectors may cause nonspecific inflammation and antiviral cellular response [42]; this problem still needs to be solved.
