Introduction:

GUMBOHATCH® is a new immune-complex vaccine against Infectious bursal disease (IBD) developed by HIPRA (Spain). This new immune-complex vaccine has introduced a different formulation (IgY of egg origin) and control parameters (free IgY detection and neutralization control) to ensure the complete coating of the IBDV virus.

All these new improvements have resulted in a newly formulated immune-complex vaccine, which ensures the maintenance of the maximum potency of the vaccine and consistent results in the field, even in the presence of high levels of maternal antibodies¹.

The present multicentre, positive-controlled and blind clinical trial was performed with the aim of evaluating the safety and efficacy of GUMBOHATCH® (immune-complex vaccine against Infectious bursal disease) when administered via the subcutaneous route under field conditions compared with a standard formulated immune-complex vaccine in Europe.

Methods:

A total of 160,731 one-day-old chicks were vaccinated via the subcutaneous route with GUMBOHATCH® (n= 77,152) or with a commercial IBD-complex vaccine (n=83,579) as a standard vaccine, following the manufacturer’s instructions. After vaccination, the chicks were distributed to 2 commercial broiler farms in France and to one farm in Belgium.

On each farm the two groups were housed in separate units under identical conditions and monitored up to the end of rearing (35 days of life). Several safety and efficacy parameters were evaluated during this period.

Blood sampling and necropsy of 15 chicks per group and farm were performed at different time points. Antibody titres to the IBD virus were determined using CIVTEST® AVI IBD (HIPRA). During necropsies macroscopic bursal lesions were evaluated and bursal imprints on FTA cards were collected for PCR analysis. Data from the three farms were analyzed altogether.

• SAFETY: No adverse reactions to either of the two vaccines were observed. Similar hatchability and body weight after hatching were also observed in both groups.

• EFFICACY: No clinical outbreak of IBD occurred on any of the farms, so no impact was expected on the productive parameters regarding the use of the two different vaccines (Table 1).

PCR results from bursal imprints (Figure 1) and BB ratio evidenced replication of the vaccine virus from day 21 onwards in both groups.

The evolution of antibody titres to the IBD virus after vaccination followed a similar pattern in both groups, with a progressive decrease in maternally-derived antibodies between days 0 and 21, followed by a rapid increase in vaccine-induced antibodies from day 28 onwards up to the end of rearing.

However, statistically significant differences (p<0.05) in vaccine-induced antibody titres were detected on days 28  and 35 in favour of the GUMBOHATCH® group, evidencing a faster humoral protection (Figure 2).

Also, a numerical difference was observed in the percentage of serological positivity between groups, with a higher number of positive animals in the case of GUMBOHATCH® at 28 and 35 days (Figure 3).

Conclusions

The results obtained in this study allow the conclusion to be drawn that vaccination with GUMBOHATCH® is safe and confers a faster humoral protection against IBD when administered via the subcutaneous route under field conditions.

The more rapid humoral response observed with GUMBOHATCH® compared to a standard formulated vaccine, may correspond to the new formulation and controls performed that prevent the neutralization of the vaccine virus when in contact with high levels of maternal antibodies.

REFERENCES:

¹Perozo et al. 2019. World Veterinarian Poultry Association Congress. 0262.60 (3), 603-612.

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