A NEW VACCINE FOR THE PREVENTION OF EPIZOOTIC HAEMORRHAGIC DISEASE IN CATTLE

The IZSAM institute recently concluded a research study leading to the development of a safe and effective inactivated vaccine against a specific strain of the virus responsible for the Epizootic haemorrhagic disease (EHD). EHDV, not dangerous for humans, primarily affects wild and domestic ruminants, including cattle, and is transmitted through bites of Culicoides midges.

Clinical signs in affected animals vary, ranging from milder ones, such as fever, reddened conjunctiva, and drooling, to more severe signs like erosions of the oral and nasal mucosa, lameness, weight loss, difficulty breathing and death.

The virus has historically been recorded in Japan, Australia and North America, where the most affected species is the white-tailed deer. However, in recent years, it has spread to European cattle, raising alarm among farmers.

EHDV comprises seven serotypes (1, 2, and 4-8), each with characteristics that can influence both the immune response and the severity of the disease. Recently, outbreaks caused by serotypes 6 and 7 have progressively emerged in the Mediterranean basin, especially in the Middle East and Northern Africa.

In 2022, serotype 8 appeared in Europe, likely due to infected midges carried by winds from Northern African countries. Several cases have been recorded in Italy - even though they were contained in the regions of Sicily and Sardinia - and in Spain. The spread to other European countries, such as France and Portugal, is causing concern among farmers who fear serious economic impact for the livestock industry.

Given the lack of measures to prevent further virus spread in Europe, IZSAM developed an inactivated vaccine containing the dead (inactivated) virus (vEHDV8-IZSAM), and tested it on the target species.

The experiment was conducted on Holstein-Friesian calves according to the protocol approved by the Animal Care and Welfare Board of the IZSAM, and authorized by the Italian Ministry of Health. The results have been published in the scientific journal Virus Research.

The selected calves were assigned to two groups: the first received two doses of the inactivated vaccine administered 21 days apart, while the second group (control) received a placebo. Subsequently, both groups were experimentally exposed to the EHDV-8 virus to test the vaccine’s capability to protect from disease.

The results of this study, whose lead authors are Dr. Massimo Spedicato and Dr. Gaetano Federico Ronchi, showed that vaccinated calves developed an immune response that prevented the appearance of both clinical signs of the disease and viremia (the presence of the virus in the blood). In contrast, animals belonging to the control group exhibited both clinical signs and viremia.

“Not only does this vaccine prevent clinical signs in cattle – says Dr. Spedicato - but it’s also important to highlight the complete absence of viremia in vaccinated calves exposed to the virus. This factor is crucial for limiting the further spread of EHDV-8”

Further studies are underway to verify the vaccine’s efficacy in real-world settings, by increasing the number of animals involved in the experiment and assessing the potential need for annual booster doses. “We believe - Dr. Ronchi adds – that this vaccine has great potential for controlling and preventing EHDV-8 outbreaks in cattle, both in Italy and in the rest of Europe, thereby filling an important gap in disease management”.