NASYM, a live intranasal vaccine, protects young calves from bovine respiratory syncytial virus in the presence of maternal antibodies

Abstract

Background: Bovine respiratory syncytial virus (BRSV) is a major problem for cattle worldwide during their first year of life. The aim of the present study was to evaluate efficacy and longevity of immunity of a live vaccine (NASYM, HIPRA) in the presence of maternally derived antibodies (MDA). Method: Calves (36) were distributed in four groups, based on MDA status and treatment. They received NASYM or a placebo at an early age (less than two weeks) by intranasal route. Eight weeks later, animals were challenged with the Asquith strain of BRSV. Efficacy was assessed by monitoring clinical signs and mortality, PaO 2 , virus shedding and lung lesions. The immunological response was evaluated by measuring IgG in serum and IgA in nasal secretions. Results: A reduction of mortality, lung lesions, shedding and a higher PaO 2 was achieved in NASYM vaccinated groups, independently of MDA status. An anamnestic IgG response was observed after challenge in vaccinated animals, both in MDA+ and MDA-groups. An IgA response was also observed in vaccinated animals after vaccination and challenge. Conclusion: NASYM protected newborn calves with MDAs during the first 10 weeks of life, against a very virulent challenge that caused extensive pulmonary lesions and deaths in control animals, with just a single intranasal dose.

Bovine Respiratory Disease Complex: Prevalence of the Main Respiratory Viruses Involved in Pneumonia in Spain

“…Other studies have reported that its prevalence within BRD is 60% in dairy cattle [18] and up to 70% in beef cattle [19]. These results are not surprising, since infection with BRSV is the major cause of BRD in cattle worldwide, especially during their first year of life [20]. Due to the nature of the service, it is difficult to classify samples by production type, so the results obtained represent both systems, dairy and beef.…”

“…Calves between one and three months of age are most susceptible to BRSV, while maternal derived antibodies (MDAs) are still present. Intranasal BRSV vaccines have demonstrated to be effective in the presence of MDAs; however, the route of administration may not be the only factor related to the efficacy of these vaccines [20]. For instance, a commercial vaccine available in Europe that can be used from the first day of life had reduced efficacy against BRSV in calves vaccinated in the presence of MDAs -according to the summary of product characteristics [20,21].…”

“…There is a need for a multivalent vaccine including the most relevant viruses with an IBR-On the other hand, a monovalent BRSV vaccine demonstrated to significantly reduce viral shedding, clinical signs, lung lesions and mortality even in the presence of MDAs. Protection was shown until at least ten weeks of age, when an intramuscular booster would commonly be applied, for instance through a multivalent vaccine, especially if containing the same strain [20]. Some authors have suggested this heterologous prime-boost approach as a possible solution to overcome BRSV-related problems.…”