On days 7 and 12 post-challenge (days 35 and 40 post-immunization), calves immunized with either rLasota/gDFL or rLasota/gDF virus had higher levels of serum neutralizing antibodies (ranging from 1:80 to

1:1280) against BHV-1 compared to check details the control rLaSota calves (1:40) (Table 4). The level of serum neutralizing antibodies in two animals (R42 and R45) of rLaSota/gDFL group was 32 and 16 times higher than those of the calves of control rLaSota and rLaSota/gDF groups, respectively (Table 4). This difference in the magnitude of the secondary responses support the interpretation that the initial immunization with rLasota/gDFL was more immunogenic than that of rLasota/gDF, consistent with the better protective efficacy observed with rLasota/gDFL. Bovine respiratory disease (BRD) complex is a leading cause of economic loss in the U.S. cattle industry. BHV-1 plays a major role in the BRD complex. Currently, safe and effective vaccines are not available against

BHV-1. There are also many devastating cattle diseases that are foreign to the U.S., such as Foot and Mouth disease (FMD), Rinderpest, and Rift ISRIB Valley fever. Live vaccines against these diseases based on attenuated forms of the pathogen are prohibitory in a disease-free country like the U.S. because of concerns about the introduction of live pathogen. Therefore, there is a need to develop alternative vaccine strategies for BHV-1 and these foreign animal diseases that do not involve attenuated versions of the pathogens. Among the possible strategies, one of the most promising is the use of live viral vectored vaccines. The major advantage of a live viral vectored vaccine is that they do not require

the use of the whole infectious pathogen but can have the efficacy of a live-attenuated vaccine. NDV has several features that make it a promising viral vaccine vector. NDV grows to high titers in embryonated chicken eggs and in cell lines. In contrast to other viral vectors that encode large number of proteins, such as herpes viruses and pox Histone demethylase viruses, NDV encodes only eight proteins; therefore, there is less competition for immune responses between vector proteins and the expressed foreign antigen. NDV replicates in the cytoplasm and does not integrate into the host cell DNA. Genetic exchange is either rare or does not occur in NDV, as with other NNSV, thus making it a stable vaccine vector. NDV can infect efficiently via the IN route and induce local IgA and systemic IgG antibody and cell-mediated immune responses. NDV vectors are available that are based on lentogenic strains that are already in widespread use as live vaccines and pose no danger to the poultry industry. NDV is an avian virus, but is capable of infecting non-avian species including cattle [29] and [38]. NDV is attenuated in non-avian species due to a natural host-range restriction.