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Prevention and control against egg-drop syndrome with good results. When the birds
Fowl adenoviruses are associated with mild and severe diseases are vaccinated at 14–16 week of age, the immunity will last up
in poultry; IBH, HPS and GE are economically important to a year (Baxendale et al., 1980; Kaleta et al., 1980; Solyom et
(McFerran and Smyth, 2000). EDSV is widely distributed in al., 1982; Cook, 1983). EDSV fibre protein expressed by E.coli
domestic and wild ducks and geese. Infection of chickens with induced a high neutralizing antibody titre after two vaccinations
EDSV causes major economic losses due to its direct effect on that lasted more than 50 weeks of lay (Gutter et al., 2008). A
egg production and eggshell quality (Kang et al., 2017). HEV is further engineered fibre protein expressed in E. coli prevented
associated with acute haemorrhagic gastro-intestinal disease of clinical signs of the disease when the vaccinated chickens were
6–11-week-old turkeys and ablation of the humoral and cellular challenged with a pathogenic EDSV (Harakuni et al., 2016).
immune response (Dhama et al., 2017). There are live attenuated virus vaccines available that would
In general, avian adenoviruses are quite resistant to inactivation provide good protection against HE of turkeys (Pierson and
and persist in the environment for a long period of time. Manage- Fitzgerald, 2013; Dhama et al., 2017). The orally administered
ment practices and good biosecurity are very important, however cell culture vaccine is commercially available and recommended
because of the vertical viral transmission and co-infection with in many countries (Fadly et al., 1985; Barbour et al., 1993).
other viruses, such as IBDV and CAV, which could enhance path- Genetic engineering techniques have been also utilized to gen-
ogenicity (Hess, 2013), the control of the diseases often seems to erate subunit vaccines against HEV. The earlier ones expressed
be difficult. Therefore, vaccination is generally recommended and the major immunogenic protein, the hexon, either by a bacterial
practised with promising successes. system or through a fowlpox virus vector (van den Hurk and van
Protective antibody response is detectable after one week of Drunen Littel-van den Hurk, 1993; Cardona et al., 1999, 2001).
infection with fowl adenoviruses (Hess, 2013). The first suc- A recombinant penton-fibre knob subunit vaccine has also been
cessful protection of chickens against inclusion body hepatitis developed and it is marketed in certain countries (Pitcovski et al.,
through vaccination was reported over 40 years ago (Fadly and 2005).
Winterfield, 1975). Both live and inactivated vaccines containing Commercial vaccines, inactivated or live attenuated, are avail-
different serotypes have been evaluated. In Australia, an FAdV-8b able to control diseases caused by avian adenoviruses. Inactivated
strain-based commercially available live vaccine is given to broiler EDSV vaccines are available in many countries including the
breeders. However, IBH outbreaks in broilers were reported and USA, as either monovalent or multivalent (e.g. Agrovet, Volvac ®
it was shown that the disease resulted from alternative FAdV AC, Boehringer Ingelheim Vetmedica Inc, etc.). Other vaccines
strains of different species (Steer et al., 2011). Inactivated, wild to EDS, available in other countries but not in the USA, are
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type FAdV-8 and FAdV-11 strains have been successfully used prepared as multivalent vaccines (e.g. Volvac ) for infectious
to confer protection via maternal antibodies to broiler-breeders bronchitis and HPS/IBH (FAdV-4/8). Subunit vaccines for EDS
when grandparents were vaccinated (Alvarado et al., 2007). In (knob fibre protein), delivered by subcutaneous or intramuscular
some countries, for example Canada, the broiler breeders are vac- injections, have also been licensed in many countries including
cinated with autogenous vaccines against IBH, resulting in greatly the USA. Such vaccines are also prepared as multivalent ones for
reduced mortality (Brash, 2012). In many countries, vaccines other poultry diseases namely Newcastle disease and infectious
derived from liver homogenate are commonly used against HPS/ bronchitis (e.g. Phibro Vaccines).
IBH (Asthana et al., 2013). Effective protection of the progeny Vaccines to HE can be generated from spleen homogenates
of chickens against HPS/IBH is achieved by dual vaccination obtained from 6-week-old turkeys inoculated with an avirulent
of breeders with killed FAdV-4 and CAV (Toro et al., 2002). HEV strain. However, live-attenuated vaccines obtained from
Virulent FAdV-4 isolates were attenuated by adapting to grow in cell culture systems or originating from other avian species are
a quail fibroblast cell line (QT-35) or in SPF chicken embryos available commercially (Dhama et al., 2017). For example, some
and applied as vaccines (Schonewille et al., 2008; Mansoor et al., HE vaccines are of pheasant origin (e.g. Ceva Adenomune™) or
2011). Immunization resulted in reduced mortality upon FAdV-4 propagated in Marek’s disease induced B-lymphoblastoid cell
challenge of the chicks but did not prevent virus shedding. Simi- line (MDTC-RP19) of turkey origin (e.g. Arko Laboratories
larly, administration of FAdV-1 to SPF broiler chickens did not Ltd). Both vaccines are administered in the drinking water to
prevent virus shedding but protected against clinical signs of GE 30-day-old turkeys. Subunit vaccines that consist of the fibre
(Grafl et al., 2014). In addition to whole virus vaccines, subunit knob protein have also been developed to control HE (e.g. Abic
vaccines with the primary FAdV antigens, the hexon, penton base Biological Laboratories Teva Ltd).
and fibre were also reported. When baculovirus expressed puri- Autogenous vaccines are formalin-inactivated liver homoge-
fied fibre 2 protein of FAdV-4 was administered intramuscularly nates used to control mainly HPS (Mansoor et al., 2011).
to 1-day-old chickens the mortality was reduced to 3.5% after Commercial inactivated vaccines to control HPS/IBH are avail-
challenge with a virulent virus (Schachner et al., 2014). Similarly, able in many countries but not in the USA. These vaccines are
E. coli expressed purified FAdV-4 penton base provided 90% pro- directed mainly to FAdV-4 and FAdV-8a and available as either
tection against subcutaneous challenge 2 weeks later (Shah et al., monovalent or bivalent versions. These vaccines are also available
2012). as multivalent forms for the control of other poultry diseases (e.g.
Oil adjuvanted killed vaccines are used for the immunization Avimex Animal Health and Boehringer Ingelheim Vetmedica