Protection of chickens vaccinated with combinations of commercial live infectious bronchitis vaccines containing Massachusetts, Dutch and QX-like serotypes against challenge with virulent infectious bronchitis viruses 793B and IS/1494/06 Israel variant 2

Abstract

Infectious bronchitis virus (IBV) is a coronavirus which affects chickens of all ages. IBV mainly causes respiratory disease but can also result in reduced weight gain, reduced egg production, increased frequency of abnormal eggs and increased rates of mortality. Vaccination is the most important way to control the disease. Nevertheless, novel strains of infectious bronchitis (IB) continue to emerge in the field. In order to respond promptly, combinations of existing IB vaccines are frequently tested to see whether they can provide cross-protection. The efficacy of a combination of vaccines based on Massachusetts, Dutch and QX-like IB strains against emerging IB Israel variant 2 and IB 793B strains was assessed by means of four challenge studies. At least 80% of the birds vaccinated with IB H120 (Mass type) combined with IB D274 (Dutch type) followed by a QX-like IB vaccine booster or vaccinated with a combination of IB H120, IB D274 and QX-like IB were protected against a challenge with IB 793B. In addition, IB 1263 (Mass type) boosted by QX-like IB showed an 85% protection following challenge with IB 793B. A combination of IB H120 and IB D274 boosted by QX-like IB vaccine conferred 70% protection whilst H120 and IB D274 combination on its own showed 61.1% protection against Israel variant 2 challenge. IB 1263 boosted by a QX-like IB vaccine showed 50% protection against IB Israel variant 2. Therefore, it can be concluded that a combination of the IB H120, IB D274 and QX-like IB confers broad protection against different non-related virulent IB strains.

Field Efficacy of an Attenuated Infectious Bronchitis Variant 2 Virus Vaccine in Commercial Broiler Chickens

“…The maximum IBV ELISA antibody titers were detected at day 1 of age (i.e., MDA titers) and at 28 days of age (i.e., 12th day post-second IBV vaccination with H120). The observed low to moderate levels of IBV ELISA antibody titers at the 14th day of age in 60% of vaccinated birds were similar to other observations with both vaccine strains [ 30 , 31 , 32 ] and virulent IBV inoculation [ 33 ]. The high IBV HI antibody titers until the 35th day of age and the high antibody ELISA antibody titers at the 28th day of age were almost similar to the data reported previously with Massachusetts and 793B serotype IBV vaccines [ 34 ].…”

Research Note: First evidence of infectious bronchitis virus Middle-East GI-23 lineage (Var2-like) in Germany

“…The peculiarity of symptoms was mild, and losses were low compared with other outbreaks, and this can be because of the vaccination scheme, consisting of 2 live-attenuated vaccines used. A combination of 2 live-attenuated vaccines from the genotype QX and Massachusetts and D274 combined with H120, respectively, was shown to have 50 and 70% protection (Bru et al, 2017).…”

Pathogenic characteristics of a QX-like infectious bronchitis virus strain SD in chickens exposed at different ages and protective efficacy of combining live homologous and heterologous vaccination

“…Analyses of genetic evolution, antigenicity and pathogenicity reveal many major differences among QX-like IBVs and other serotypes [17,[27][28][29]. Several QX-like IBV vaccines have also been developed to combat infections induced by the virus [30][31][32][33].…”