E. coli vaccine stable when rehydrated with diverse water types or combined with coccidiosis vaccine

A modified-live Escherichia coli vaccine remained “extremely” stable when rehydrated with diverse types of water and when it was combined with a coccidiosis vaccine, indicate the results of a recent study.

Throughout Europe and elsewhere, poultry producers use different types of water to “suspend” or rehydrate poultry vaccines before diluting them to either spray on birds or add to drinking water; different vaccines are also administered together to save on time and labor, said Gerhard Glünder, Dr. med. vet., of the Clinic for Poultry, University of Veterinary Medicine, Hannover, Germany.

Glünder and colleagues sought to determine if these common practices would affect the stability of Poulvac E. coli, a live vaccine manufactured by Zoetis, which sponsored the study. Zoetis recommends the vaccine be rehydrated with cool distilled[1] or chlorine-free water[2], depending on the region.

First the researchers tested the stability of the E. coli vaccine alone with either cold tap water, demineralized water, isotonic salt solution, bottled water, demineralized water with a THIO tracer (a stabilizer) or hot tap water that was 40° C (104° F). They rehydrated the vaccine (one dose/0.5 ml) in each type of water, then stored the reconstituted vaccine preparation at 25° C (77° F) or 40° C (104° F) to mimic possible real-world conditions.

At 2, 4 and 24 hours after preparation, the researchers tested for stability, which was determined based on E. coli cell counts per dose in the stored solutions as compared to cell counts immediately after rehydration.

The vaccine was stable under realistic conditions. Even when stored at 40° C (104° F), no significant losses in stability occurred (Figure 1), Glünder said at the 2015 World Veterinary Poultry Association congress in Cape Town, South Africa.

Figure 1. Stability of E. coli vaccine after suspension in various types of water. Deviation of E. coli counts from the initial value (log10) set equal to zero

Next the researchers combined one dose of the E. coli vaccine with one dose of either Paracox-5 or Paracox-8, which are coccidiosis vaccines.

Because coccidiosis vaccines are often used with dye to help ensure uniform application when sprayed onto chicks at 1 day of age, the researchers also tested for interactions between the E. coli vaccine and the coccidiosis vaccines with and without dye. A suspension of the E. coli vaccine in demineralized water served as a control.

The E. coli vaccine was stable when combined with the coccidiosis vaccines with and without dye (Figure 2), he said.

Figure 2. Stability of E. coli vaccine combined with coccidiosis vaccines with and without dye. Deviation of E. coli counts (log10) from the initial value of the pure E. coli vaccine set equal to zero

  “It could clearly be demonstrated that the live E. coli vaccine is extremely stable in the diverse suspension media tested for even a longer time than the vaccination period of 2 hours recommended under field conditions,” Glünder said.

Furthermore, the in vitro studies demonstrated that adding a coccidiosis vaccine had no adverse effects on the E. coli vaccine, he concluded.

[1] Poulvac E. coli. Zoetis United States. https://www.zoetisus.com/products/poultry/poulvac-e-coli.aspx

[2] Annex 1. Summary of product characteristics.
http://www.ema.europa.eu/docs/en_GB/document_library/EPAR_-_Product_Information/veterinary/002007/WC500138144.pdf

This article contains information on veterinary products based on international registration dossiers. The registered indications as well as safety and efficacy assessment for specific products may vary with local regulations and approvals. Always refer to the product label specific to your market for usage guidelines. Product and trademark registrations may vary by country. Contact your Zoetis representative for availability.