Current Progress of Avian Vaccines Against West Nile Virus

Abstract

Birds are the main natural host of West Nile virus (WNV), the worldwide most distributed mosquito-borne flavivirus, but humans and equids can also be sporadic hosts. Many avian species have been reported as susceptible to WNV, particularly corvids. In the case that clinical disease develops in birds, this is due to virus invasion of different organs: liver, spleen, kidney, heart, and mainly the central nervous system, which can lead to death 24–48 h later. Nowadays, vaccines have only been licensed for use in equids; thus, the availability of avian vaccines would benefit bird populations, both domestic and wild ones. Such vaccines could be used in endangered species housed in rehabilitation and wildlife reserves, and in animals located at zoos and other recreational installations, but also in farm birds, and in those that are grown for hunting and restocking activities. Even more, controlling WNV infection in birds can also be useful to prevent its spread and limit outbreaks. So far, different commercial and experimental vaccines (inactivated, attenuated, and recombinant viruses, and subunits and DNA-based candidates) have been evaluated, with various regimens, both in domestic and wild avian species. However, there are still disadvantages that must be overcome before avian vaccination can be implemented, such as its cost-effectiveness for domestic birds since in many species the pathogenicity is low or zero, or the viability of being able to achieve collective immunity in wild birds in freedom. Here, a comprehensive review of what has been done until now in the field of avian vaccines against WNV is presented and discussed.

The Role of Birds of Prey in West Nile Virus Epidemiology

“…These have been in use for over ten years and are highly effective at preventing infection if used appropriately, specifically annual booster injections used to maintain protection. Despite the clear evidence of disease in some avian species, there are no licensed vaccines for use in birds, as recently reviewed by Jiménez de Oya and colleagues [ 110 ]. However, most vaccine candidates have demonstrated the development of anti-WNV antibodies in several bird species including raptors and some studies were able to confirm that these vaccines conferred partial protection from virus challenge [ 111 , 112 ].…”

Animal and Human Vaccines against West Nile Virus

“…Birds are the natural hosts of WNV and play a key role in the epidemiology of the virus, being many species susceptible to the infection, particularly corvids [4,25]. The disease shows up due to virus invasion of different organs: liver, spleen, kidney, heart, and mainly the central nervous system, and can lead to death within 24-48 h later [26,27]. Several commercial and experimental vaccine candidates have been assayed in wild and domestic birds, although not one has yet been authorized for use on them [27].…”

West Nile Virus: An Update on Pathobiology, Epidemiology, Diagnostics, Control and “One Health” Implications

“…There have been several reviews covering various aspects of WNV, including virus ecology and pathobiology [ 1 , 47 , 48 , 49 , 50 ], epidemiology [ 1 , 51 , 52 , 53 ], medicine and clinical pathology [ 1 , 44 , 52 , 54 ], and vaccine development [ 55 , 56 , 57 ]. This review provides a comprehensive update on WNV, focusing on virus biology and pathobiology, epidemiology, diagnostics, public and One Health importance and control, including new approaches made towards vaccine development, as well as other modes of prevention and treatment.…”