Host Factors Affecting Generation of Immunity Against Porcine Epidemic Diarrhea Virus in Pregnant and Lactating Swine and Passive Protection of Neonates

Abstract

Porcine epidemic diarrhea virus (PEDV) is a highly virulent re-emerging enteric coronavirus that causes acute diarrhea, dehydration, and up to 100% mortality in neonatal suckling piglets. Despite this, a safe and effective PEDV vaccine against highly virulent strains is unavailable, making PEDV prevention and control challenging. Lactogenic immunity induced via the gut-mammary gland-secretory IgA (sIgA) axis, remains the most promising and effective way to protect suckling piglets from PEDV. Therefore, a successful PEDV vaccine must induce protective maternal IgA antibodies that passively transfer into colostrum and milk. Identifying variables that influence lymphocyte migration and IgA secretion during gestation and lactation is imperative for designing maternal immunization strategies that generate the highest amount of lactogenic immune protection against PEDV in suckling piglets. Because pregnancy-associated immune alterations influence viral pathogenesis and adaptive immune responses in many different species, a better understanding of host immune responses to PEDV in pregnant swine may translate into improved maternal immunization strategies against enteric pathogens for multiple species. In this review, we discuss the role of host factors during pregnancy on antiviral immunity and their implications for generating protective lactogenic immunity in suckling neonates.Pathogens 2020, 9, 130 2 of 21 PEDV [2]. The increased rates of protection were associated with high titers of sIgA antibodies in colostrum and milk [2]. This demonstrates that protecting suckling piglets from devastating enteric viral pathogens is dependent on efficient trafficking of intestinal IgA + plasmablasts to the mammary gland (MG) and accumulation of sIgA antibodies in milk, defined as the gut-MG-sIgA axis [2,3]. While it is known that the migration of IgA + plasmablasts to the MG depends on the regulation of mucosal homing receptor and chemokine expression, the mechanisms that regulate this process are much less understood. Identifying variables that influence lymphocyte migration during gestation and lactation is imperative for designing maternal immunization strategies that generate the highest amount of lactogenic immune protection against PEDV in suckling piglets. In this review, we will discuss the role of host factors during pregnancy on antiviral immunity and its implications for generating protective lactogenic immunity against PEDV infection in neonatal suckling piglets. PEDV: A Re-Emerging Enteric CoronavirusPEDV is a highly virulent re-emerging enteric coronavirus belonging to the Alphacoronavirus genus within the family of Coronaviridae. Currently, there are four genera, including Alphacoronavirus, Betacoronavirus, Gammacoronavirus, and Deltacoronavirus, within the Coronaviridae family. Other alphacoronaviruses include transmissible gastroenteritis virus (TGEV) in swine, feline coronaviruses (FCoV), canine coronaviruses (CCoV), ferret enteric coronavirus (FRECV) and two human coronaviruses NL63 and 229E. Additionally, five...

Analysis of SARS-CoV-2 vertical transmission during pregnancy

“…Further studies are required to assess whether this represents an infectious and replicative virus or not and whether it may depend on viremia or other factors. It has been previously reported that other β-coronaviruses may pass through milk [37][38][39] . Although precautions were adopted, we cannot exclude a contamination of the sample by other maternal positive sites.…”

Systemic and intestinal porcine epidemic diarrhea virus-specific antibody response and distribution of antibody-secreting cells in experimentally infected conventional pigs

“…Similarly, an earlier study also detected PEDV IgA and IgG ASCs in both systemic and intestinal tissues [ 32 ]. Possible explanations for this observation are that B cells that become activated and differentiated following activation by the virus are transported from the gut to the blood and other secondary lymphoid organs prior to antibody secretion [ 52 ], and/or B cells are activated in systemic secondary lymphoid tissues by PEDV antigens in systemic circulation [ 18 , 53 ]. We observed lower IgA antibody levels in the culture supernatants of MNCs isolated from intestinal tissues than those from blood and spleen (Figure 3 ).…”

The EPICENTRE (ESPNIC Covid pEdiatric Neonatal Registry) initiative: background and protocol for the international SARS-CoV-2 infections registry

“…org/news/2020/03/12/coronavirus031220), while a number of other scientific societies and bodies more optimistically recommend to breastfeed. Other β-coronaviruses, and particularly the Middle East Respiratory Syndrome coronavirus, which shares more than 50% of genetic sequence and several biological characteristics with SARS-CoV-2 [32], are known to be transmitted through breast milk in animals [33][34][35][36]. We clearly need more data, based on welldesigned, large studies analyzing breast milk samples obtained in different phases of COVID19 disease to clarify if the virus is present and transmittable and if there are any antibodies secreted in the milk.…”