The use of vegetal oil for veterinary vaccines

The effectiveness of vegetable oils in veterinary vaccine formulations is a topic that often sparks curiosity, although replacing mineral oil with vegetable oil may seem appealing, it has been shown that formulations containing vegetable oils are not as potent in boosting immunity and may be unstable when compared to the same formulations using mineral oils, however with the current advances in technology this paradigm could change soon.  

Vegetable oils are derived from various sources such as canola, coconut, corn, cottonseed, olive, palm, palm kernel, peanut, safflower, and soybean. They are commonly used to enhance the flavor and texture of food, as well as in cooking. These oils undergo an extraction and processing procedure before being refined to reach the desired purity level.

The quest to discover a vegetable oil appropriate for vaccines is motivated by two key factors. Firstly, using mineral oil in vaccines has been linked to adverse local reactions. Secondly, there are reservations regarding the potential side effects in individuals who consume meat or milk from animals immunized with this substance. Despite numerous trials, identifying an oil that can elicit a potent immune response without any negative side effect or traces of residual oil continues to be challenging.

Studies performed with Miglyol (1,3-butanediol and plant-derived caprylic/capric fatty acids) have shown significantly lower immune response when compared to mineral oil-based adjuvants (1). The research paper demonstrates that using biodegradable oils in vaccinations resulted in a significantly lower immune response and, therefore, provided less protection compared to traditional mineral oil formulations with the same antigen. This is believed to be due to the depot effect and the likelihood that biodegradable oils are more easily broken down by enzymatic reactions, leading to a faster release or dispersion of the antigen in the formulations rather than activation of the immune system, as mineral oil does.

It has been observed that other factor could affect the immune response such as the emulsion’s viscosity and particle size. For instance, chickens vaccinated with higher viscosity emulsions tend to have a lower immune response than those immunized with less viscous formulations (2). When evaluating an emulsion, the oil type is just one parameter to consider. The emulsion’s droplet size and water-to-oil ratio also play an important role in the immune response.

Work performed with olive oil, peanut oil, and sunflower oil associated with Ginseng saponin has shown promising results and low local reactions, suggesting that this can be one alternative and, other oils, such as soybean combined with vitamin E and ginseng saponin, have been shown good antibody titers, and local reaction (2,3,4).

It’s important to note that using saponin ginseng as an adjuvant in chickens has been found to elicit a strong immune response when administered with Newcastle vaccine and emulsions containing mineral oil. This is in contrast to the common Qulilara Saponin, which is not recommended for use in chickens.

It’s not just viruses that can be combined with vegetable oils – bacterial diseases like bordetella bronchiseptica, which is a major problem in China’s rabbit industry, have shown promising results with mineral oils like E515, and vegetable oils like soybean oil, vitamin E, and ginseng, had showed good antibody response (4,5).

The vaccine industry has raised significant concerns surrounding the use of vegetable oils and the variability in crops and seasons across different regions that may lead to batch-to-batch differences, which could potentially intensify the innate biological variability of vaccines.

Previous animal health products have utilized vegetable oils such as olive oil, soybean, and corn but never in vaccine production. When selecting an adjuvant for a vaccine, it’s important to consider various factors such as vaccine stability, interaction with primary packaging, viscosity, syringeability, and feasibility for large-scale production. The immune response is “just” one part of the equation; although it is undoubtedly essential, using oils in a GMP environment, is complex. Even if a vaccine generates a high immune response with low local reactions, it’s not a viable solution if the adjuvant oil selected cannot be used in commercial-scale GMP production. Furthermore, the cost of raw materials is also a significant consideration when selecting an adjuvant oil, making the choice complex.

Thanks to the latest technological advancements, we now access highly effective adjuvants like AdjuVac (https://esadjuvants.com/product which can be safely used with oils to produce strong immune responses while minimizing local reactions. Furthermore, mineral oils such as Ondina X (https://www.shell.com/business-customers/lubricants-for-business/process-oils/shell-ondina-x-as-animal-vaccine-adjuvant.html are now readily available and leave behind an extremely low residual effect. This simplifies the local reaction, residual effect, and immune response balance. For more information, you can visit the product page links provided.

Sunflower	Avocado	Sesame oil	Cod Liver
Olive oil	Almond	Cottonseed oil	Mink
Soybean	Fish	Castor oil	O. roughy fish
Corn oil	Shark	Peanut
Miglyol	Orange roughy	Apricot

Literature:

1. Stable URL: http://www.jstor.org/stable/1591665
2. Vaccines 2020, 8, 180; doi:10.3390/vaccines8020180
3. http://dx.doi.org/10.14737/jimb.2307-5465/2.1.6.10
4. Doi:10.1128/CV1.00127-14
5. Vaccine23(2005)1053-1060
6. Vaccine monitor, vol.25,no.2,pp.55-59,2016
7.