Passive Transfer of Naturally Acquired Specific Immunity against West Nile Virus to Foals in a Semi-Feral Pony Herd

Abstract

Horses naturally exposed to West Nile Virus (WNV) or vaccinated against WNV develop humoral immunity thought to be protective against development of clinical disease in exposed or infected animals. No reports evaluate the efficacy of passive transfer of naturally acquired specific WNV humoral immunity from dam to foal. The purpose of this study was to investigate passive transfer of naturally acquired immunity to WNV to foals born in a herd of semi-feral ponies, not vaccinated against WNV, in an endemic area, with many dams having seroconverted because of natural exposure. Microwell serum neutralization titers against WNV were determined in all mares and foals. Serum IgG concentration was determined in foals by serial radial immunodiffusion. Differences in IgG concentration between seropositive and seronegative foals were examined by means of the Mann-Whitney U-test. Linear regression was used to evaluate the association between mare and foal titers. Seventeen mare-foal pairs were studied; 1 foal had inadequate IgG concentration. IgG concentration was not different between seronegative and seropositive foals (P = .24). Mare and foal titers were significantly correlated in foals with adequate passive transfer of immunity (Spearman's rho = .84; P < .001); >90% of the foal's titer was explained by the mare's titer (R2 = 0.91; P < .001). Passive transfer of specific immunity to WNV is present in pony foals with adequate passive transfer of immunity born to seroconverted mares.

Passive immunisation, an old idea revisited: Basic principles and application to modern animal production systems

“…Just like ruminant neonates, foals acquire immunoglobulins from the dam's colostrum by enteric uptake during a limited 'open gut' period just after birth as for example illustrated by passive transfer of immunity against West Nile Virus and rotavirus from dam to foal (Sheoran et al, 2000;Wilkins et al, 2006), and indeed several licensed vaccines for horses are available (Wilson, 1999) providing maternal passive immunity for foals against many diseases (see Table 3). The foal are usually re-vaccinated four months after parturition (Wilson, 1999).…”

Change of antibody levels to ferritin in the sera of foals after birth: Possible passive transfer of maternal anti‐ferritin autoantibody via colostrum and age‐related anti‐ferritin autoantibody production

“…In bovines, colostral ferritin and maternal autoantibodies (IgG and IgM) to ferritin are likely to be transferred to newborn calves (Kanno et al 2013). Colostrum-fed foals showed a sharp increase in ferritin antibody activities after 2 weeks of age, suggesting that maternal anti-ferritin autoantibody is passively transferred via colostrum (Wilson et al 2001;Holznagel et al 2003;Giuère & Polkes 2005;Wilkins et al 2006). We examined the relative activities of antibodies to ferritin in three colostrum samples.…”

“…The high ferritin-binding activity observed just after birth suggests that FBPs, probably including antibodies to ferritin, are involved in iron metabolism during foal growth (Ohya et al 2011). In assessment of colostral transfer of IgG, the failure of passive transfer of immunoglobulin via colostrum showed the decrease of IgG to specific pathogens as compared with foals with passive transfer of colostrum (Erhard et al 2001;Wilkins et al 2006). Further studies are needed to examine the effects of defective transfer of antibodies to ferritin on foal iron metabolism.…”

Seroprevalence of West Nile Virus in Feral Horses on Sheldon National Wildlife Refuge, Nevada, United States

“…[1][2][3][4] The Bureau of Land Management currently manages an estimated 33,700 wild horses in 10 of the western United States. 5 As part of the management of these herds, non-domestic horses are routinely rounded up or "gathered" by natural resource management agencies to reduce populations.…”