MSP^® IMMUNITY contributes to limit the diffusion of marek’s virus disease

Despite the availability of vaccines, Marek’s disease continues to threat the poultry industry with economic losses estimated at 1-2 billion dollars per year. Indeed, the huge vaccination campaigns set up since the end of 1960 years increased the pathogenesis of the virus. Thus, current vaccines protect infected animals against the development of tumors but don’t prevent the replication and the shedding of the virus usually leading to chronical immunodepression.

To date, no treatment (other than vaccine prophylaxis) is available to control the replication of the virus and its dissemination in the environment. Consequently, it is necessary to development alternative and sustainable strategies to control MD.

Numerous scientific publications have reported that algal extracts can have different biological activities, included viral infections inhibition.

We recently demonstrated that MSP® IMMUNITY, the sulfated polysaccharides (SPs) fraction purified from green macroalgae (Ulva. sp) can activate chicken heterophils and monocytes in vitro and in vivo in standard conditions of farms. This suggested that MSP® IMMUNITY can potentially be used as an immunomudulator to reinforce natural defenses of animals and enable them to resist particularly against viral challenges.

In a new study lead in collaboration with INRAE, we explored the capacity of the same algae extracts to reduce MDV lytic replication and MDV reactivation from latently infected cells in vitro. The results demonstrated that these algae reduce significatively (80%) of the in vitro MDV viral load with a limited or no cytotoxicity.

Moreover, MDV replication is reduced, limiting the infection at the early stages of infection. These extracts already have an effect of the virus spreading, the lyse plate sizes being reduced by half compared to the not-treated infected cells.

The study finally demonstrates that these extracts could support the immune system at a later stage of infection.

Consequently, these algae extracts could represent innovative and efficient natural solutions to reduce the risk of Marek’s virus pressure in poultry industry and potentially the risks linked to another avian virus.

These results have been published in BMC veterinary research, The sulphated polysaccharides extract Ulvans from Ulva armoricana limits Marek’s disease virus dissemination in vitro and promotes viral reactivation in lymphoid cells.