The Current State of Knowledge onInnate and Adaptive Responses

during FMDV Infection

Bryan Charleston

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Diagnostic windows

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FMD virus in blood

Clinicallesions

antibody response

FMD virus at mucosal sites

Transmission

FMDV-sequence of events

Effect of CD4 T cell depletion onneutralising antibody response to

vaccination

T-dependent response to antigen

McHeyzer-Williams, L.J. & McHeyzer-Williams, M.G. Antigen-specific memory B cell development. Annu Rev Immunol 23, 487-513 (2005).

Short-lived plasma cells:Supposed to secrete Ab in situ for a short period of time within the lymphoid organ in which they are generated

Memory B cells:Recirculate between blood and tissues in a quiescent state (do not spontaneously secrete Ab)

Long-lived plasma cells:Spontaneously secrete Ab for a long period of time.Only detectable when transiting from the lymphoid organs towards specific niches (bone marrow, red pulp of spleen)

Day 7

Day 1 Day 7

MiceFMDV infection of mouse BMDCs is abortive, infected cells lose their ability to stimulate T-cells and differentiate towards a macrophage-like phenotype.

Generalized suppression of T-dependent responses has been observed in vivo in mice between 3 and 5 days p.i., thought to be mediated in part byMHC class II and CD40 downregulation on DCs and by IL-10.

FMDV infection induces a reduction in splenic plasmacytoid dendritic cells (pDCs) and conventional DCs (CD11c+ /CD8a+).

Antigen presentation

PigsFMDV infection of porcine pDCs, monocyte derived DCs (MODCs) and BMDCs is abortive.

Porcine MODCs respond in vitro by increasing expression of MHC class II and CD86,But data generated in vitro from cells derived from infected pigs are moreconsistent with the suppressive responses described in vitro and in vivo in mice.

Cattle FMDV infection of bovine MODCs is productive and infected cellsdie, losing their ability to stimulate T-cell proliferation in vitro.

Immune complexs induce low quantities of IFN from pDC

No reports of generalized immunosuppression during the acute phase of FMDV infection in cattle.

Antibody mediated infection/ uptake of virus and antigen

Acute FMD: naïve buffalo

Windsor et al., 2011

Reid et al., 2011

Biologically active type 1 IFN

Days post challenge

I.U./

ml I

FN

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X1X2X3X441718192526334344476061

Acute FMD: naïve buffalo

Days post challenge

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/ml

Day 0

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Buffalo leucocyte count (n = 16)

Windsor et al., 2011

Bovine B cell response to antigen

TD antigen-specific response FMDV-specific response

FMDV D46 DAPI

LZ

DZFMDV D46

80 µm

MLN 38DPCI

Budras, Bovine Anatomy

Follicles with central crypt

Casteleyn et al.,

M Hofmeyr

FMD: buffalo

Fundamental differences between cattle and human antibodies

Variable (VH)

Diversity (DH)

Junctional (JH)

Constant (CH)

Germline

κλ

Variable (VL)

Junctional (JL)

Constant (CL)

Germline

λGene segment recombination

Gene segment recombination

Translation

-S-S--S-S-

-S-S--S-S-

3.6 x 106

potential combinations of heavy and light chains

X X XXX

X

Bimodal bovine CDR3 distribution

Bovine antibodies – long CDR3

Wang et al., 2013Cell 153 1379

Oyen et al., 2011J. Mol. Biol. 407, 138

And there are revolutions in electron microscopy…

Wonderful new detectors, that collect 4k movies, and allow virus particle movements to be tracked in software … so we can see atomic detailLive virus in cryo – in a water ‘glass’ Expensive – hence a National Facility for the UK

70hrs Collection on Polara70hrs Collection on Polara

PirbrightClare GrantVeronica CarrJohn HammondClaudine PortaNick JuleffMirrie WindsorEva PerezJulian Seago

Oxford/ DiamondDave StuartLiz FryAbhay KotechaAnna FowlerMarton Munz Gerton Lunter

ReadingIan Jones