Overall, studies have shown that the tested vaccine formulation (IVV suspension subtype H5N1 or H1N1-stabilizing media-adjuvant), regardless of age and pregnancy status of the cattle, is completely safe and not abortogenic (in both pregnant heifers and adult cows). Vaccinated animals in all age groups demonstrated increased IgG antibody responses against Omp16 and L7/L12 proteins with calves demonstrating the greatest increase in humoral responses. Following Apogossypolone (ApoG2) experimental challenge with 544, vaccinates demonstrated greater protection and no signs of clinical disease, including abortion, were observed. The vaccine effectiveness against infection was 75, 60 and 60%, respectively, in calves, heifers and adult cows. were not isolated from calves of vaccinated cattle that were experimentally challenged during pregnancy. Our data suggests that the Flu-BA vaccine is safe and efficacious in cattle, including pregnant animals; and can therefore be administered to cattle of any age. Keywords: bovine brucellosis, influenza viral vector, vaccine, registration trials, protective efficacy, calves, heifers, cows Introduction and are all considered Apogossypolone (ApoG2) to be zoonotic (OCallaghan and Whatmore, 2011). Brucellosis is one of the most common zoonotic diseases of humans, with more than 500,000 cases reported annually. Depending upon the system of controls and the socioeconomic conditions, different countries have Apogossypolone (ApoG2) reported from 0.09 to 1 1,603 cases per million inhabitants (Pappas et?al., 2006). is the primary cause of brucellosis of cattle. Because of its impact on human health, in Kazakhstan, regulatory actions for cattle herds infected with brucellosis include quarantine (Yespembetov et?al., 2019). In cattle, brucellosis can be manifested by orchitis in males, but clinical signs are primarily in females and include nonviable calves, abortions, retained placentas, and infertility (OCallaghan and Whatmore, 2011). Vaccination is an effective tool for controlling brucellosis in livestock (Garin-Bastuji et?al., 1998), and is also effective in protecting human health in endemic areas (Zinsstag et?al., 2007). Currently, brucellosis vaccines for cattle are live attenuated strains (19, 82 and RB51). Although these vaccines have high efficacy for cattle (protection against abortion >70%, complete protection against infection >50%) (Confer et?al., 1985; Stevens et?al., 1995; Cheville et?al., 1996; Cardena et?al., 2009; Ivanov et?al., 2011), they have a number of serious disadvantages including causing abortions in pregnant animals, virulence in humans, and, with the exception of strain RB51, cause high titers on brucellosis serologic tests that cannot be differentiated from responses of infected animals (Spink et?al., 1962; Beckett and MacDiarmid, 1985; Smith and Ficht, 1990). Additionally, the strain RB51 is resistant to rifampicin, an antibiotic commonly used to treat brucellosis in humans (Schurig et?al., 1991). These characteristics of commercial vaccines have limited their wide use in cattle in some Apogossypolone (ApoG2) countries. Development of an improved brucellosis vaccine for cattle with high efficacy, improved safety characteristics, and the ability to be serologically differentiated from infected animals (DIVA) would be an important advancement. Previously, attempts to develop safe and effective vaccines have utilized attenuated mutants (Vemulapalli et?al., 2000a; Vemulapalli Apogossypolone (ApoG2) et?al., 2000b; Vemulapalli et?al., 2004; Olsen et?al., 2009), subunit (recombinant proteins) vaccines (Tabatabai and Pugh, 1994; Oliveira et?al., 1994a; Oliveira et?al., 1994b; Oliveira and Splitter, 1996; Oliveira et?al., 1996; Kurar & Splitter, 1997; Al-Mariri et?al., 2001; Cassataro et?al., 2005a; Mallick et?al., 2007; Pasquevich et?al., 2009), DNA vaccines (Leclercq et?al., 2003; O?ate et?al., 2003; Cassataro et?al., 2005b; Luo et?al., 2006), RNA vaccine (O?ate et?al., 2005) and vector-based vaccines (He et?al., 2002; Cabrera et?al., 2009; Zhao et?al., 2009). The above mentioned vaccine candidates induced antigen-specific Th1 immune responses, and demonstrated protection against brucellosis challenge that SEMA3A was comparable to commercial attenuated vaccine strains (S19 or RB51) (Tabatabai and Pugh, 1994; Oliveira et?al., 1994a; Oliveira et?al., 1994b; Oliveira and Splitter, 1996; Oliveira et?al., 1996; Kurar and Splitter, 1997; Vemulapalli et?al., 2000a; Vemulapalli et?al., 2000b; Al-Mariri et?al., 2001; He et?al., 2002; Leclercq et?al., 2003; O?ate et?al., 2003; Vemulapalli et?al., 2004; Cassataro et?al., 2005a; Cassataro et?al., 2005b; O?ate et?al., 2005; Luo et?al., 2006; Mallick et?al., 2007; Cabrera et?al., 2009; Olsen et?al., 2009; Pasquevich et?al., 2009; Zhao et?al., 2009). However, the vaccine candidates were usually not tested in large animal.