function dydt = spovmivan(t,y,P0,A0,b0,k1,k_1,k2,k_2,k3)
    % [P5B] is y(1), [P5BA3] is y(2),[P5BA5] is y(3)
    sp=P0-y(1)-y(2)-y(3); % P0 is the initial SpoVM concentration,sp is the free SpoVM binding concentration
    sa=A0-y(2)-y(3); %A0 is the initial SpoIVA concentration
    dydt =zeros(3,1);
    dydt(1) = sp^5*b0*k1-y(1)*k_1-A0^3*y(1)*k2+y(2)*k_2; 
    dydt(2) = A0^3*y(1)*k2-y(2)*k_2-(A0-y(2))*y(2)*k3; 
    dydt(3) = y(2)*(A0-y(2))*k3;    
end