INFECTIVE FMDV SEROTYPES A/ARG/2001 AND O1 CAMPOS/BRA/58 HAVE DIFFERENT IMPACT ON BOVINE AFFERENT LYMPH DENDRITIC CELLS (

SORIA IVANA; FERRARIS, SERGIO; MALDONADO, VERONICA; QUATTROCCHI VALERIA; GAMMELLA MARIELA; CARRILLO, JORGE; CHARLESTON, BRYAN; CECILIA ANA LANGELLOTTI; ANGELETTI P; VAGNONI, LUCAS; ZAMORANO, PATRICIA INÉS

Bangkok

Congreso; GFRA Scientific Meeting 2019; 2019

Global Foot-and-Mouth Disease Research Alliance

Dendritic cells (DCs) play a central role in immunity. They present antigens to naive T cells and act as messengers between the adaptive and innate immune responses. In vitro differentiated DCs have been useful to understand mechanisms in the development of the immune response. Nevertheless, in vitro culture and factors used to differentiate DCs, can affect DCs physiology. As an alternative, a technique for collection of migrating DCs from lymph (ALDCs) by cannulation of bovine lymphatic vessels has been developed earlier (Charleston and collaborators, 2006).Currently used vaccines against Foot and Mouth Disease (FMD) are formulated with inactivated virus. It is known that the virus in the infective or inactive form produce different immune responses and the infective form is the most effective to limit the infection and generate immunological memory. Our group has developed several works about the differential effect that infective or inactive FMDV has on murine DCs, but comparison over bovine ALDCs has never been made.The aim of the present work was to compare how FMDV serotypes A/ARG/2001 (A2001) and O1 Campos/Bra/58 (O1C) (both included in commercial vaccine currently used in Argentina), impact on bovine ALDCs. Holstein calves were cannulated (pseudo afferent lymphatic vessels)to obtain ALDCs. ALDCs were incubated with inactive or infective virus from both serotypes.Then cellular viability was measured by anexin V/ propidium iodide staining. The presence ofthe non- structural polyprotein 3ABC, was also measured by intracellular staining using amonoclonal antibody at different times post-incubation of ALDCs with the infective virus. Theestablishment of a productive infection on lymph cells was also measured by seedingsupernatants of infected cells over BHK-21 cells. Regulation of co-stimulatory molecules CD40, CD86 and MHCII, was measured for surface staining with monoclonal antibodies after incubation of lymph cells with the infective or inactive virus.We demonstrate that neither FMDV A2001 nor FMDV O1C were capable of producing aproductive infection on lymph cells. Nevertheless, the non-structural protein 3ABC was present inside ALDCs incubated with infective A2001 virus, indicating that some viral protein expression is taking place. This did not happen with O1C serotype. ALDCs incubated with infective A2001 virus had higher apoptosis percentages than those incubated with O1C. Accordingly, costimulatory molecules CD40, CD86 and MHCII were down-regulated in ALDCs incubated with A2001 serotype. Infection with O1C only down-regulates MHCII expression on ALDCs. On the other hand, inactive forms of both serotypes up-regulates the expression of co-stimulatory molecules.We conclude that infective A2001 induce ALDCs death while O1C seems to maintain ALDCs in an immature state. Both effects would be harmful for antigen presentation to T-cells, in accordance with previously reported incapacity of FMDV infected DCs of stimulated Tdependent immune response. On the other hand, inactive forms of FMDV from both serotypes, produce ALDCs maturation thus enabling the T presentation and development of classical Tdependent immune response previously reported with the vaccine.