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				<title>Modelling the Evolution of Immunological Memory</title>
				<author>
					<firstname>Catherine</firstname>
					<surname>Lloyd</surname>
					<affiliation>
						<shortaffil>Auckland Bioengineering Institute, The University of Auckland</shortaffil>
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				<title>Model Status</title>
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            This model runs in Open Cell but due to the timescale being in days it is not able to be easily graphed in COR. The model can produce output that matches figure 2A in the published paper.  The units have been checked and they balance.
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				<title>Model Structure</title>
				<para>
ABSTRACT: Memory is a central characteristic of immune responses. It is defined as an elevated number of specific immune cells that remain after resolution of infection and can protect the host against reinfection. The evolution of immunological memory is subject to debate. The advantages of memory discussed so far include protection from reinfection, control of chronic infection, and the transfer of immune function to the next generation. Mathematical models are used to identify a new force that can drive the evolution of immunological memory: the duration of memory can regulate the degree of competition between different pathogens. While a long duration of memory provides lasting protection against reinfection, it may also allow an inferior pathogen species to persist. This can be detrimental for the host if the inferior pathogen is more virulent. On the other hand, a shorter duration of memory ensures that an inferior pathogen species is excluded. This can be beneficial for the host if the inferior pathogen is more virulent. Thus, while in the absence of pathogen diversity memory is always expected to evolve to a long duration, under specific circumstances, memory can evolve toward shorter durations in the presence of pathogen diversity.    
</para>
				
				<para>
The original paper reference is cited below:
</para>
				<para>
Evolution of Immunological Memory and the Regulation of Competition between Pathogens, Dominik Wodarz, 2003, <emphasis>Current Biology</emphasis>, 13, 1648-1652.  <ulink url="http://www.ncbi.nlm.nih.gov/pubmed/13678598">PubMed ID: 13678598</ulink>
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					<caption>Interactions between a single pathogen population and a host population.</caption>
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					<caption>Interactions between two pathogen populations and a host population.</caption>
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                     <ci>R_1</ci>
                  </apply>
               </apply>
               <apply>
                  <times/>
                  <ci>beta_2</ci>
                  <ci>R_1</ci>
                  <ci>P_2</ci>
               </apply>
            </apply>
         </apply>
      </math>
   </component>
   <component xmlns="http://www.cellml.org/cellml/1.0#" name="R2">
      <variable name="R_2" units="dimensionless" initial_value="0" public_interface="out"/>
      <variable name="alpha_2" units="first_order_rate_constant" public_interface="in"/>
      <variable name="beta_1" units="first_order_rate_constant" public_interface="in"/>
      <variable name="d" units="first_order_rate_constant" public_interface="in"/>
      <variable name="g" units="first_order_rate_constant" public_interface="in"/>
      <variable name="I_2" units="dimensionless" public_interface="in"/>
      <variable name="P_1" units="dimensionless" public_interface="in"/>
      <variable name="time" units="day" public_interface="in"/>
      <math xmlns="http://www.w3.org/1998/Math/MathML">
         <apply>
            <eq/>
            <apply>
               <diff/>
               <bvar>
                  <ci>time</ci>
               </bvar>
               <ci>R_2</ci>
            </apply>
            <apply>
               <minus/>
               <apply>
                  <minus/>
                  <apply>
                     <minus/>
                     <apply>
                        <times/>
                        <ci>alpha_2</ci>
                        <ci>I_2</ci>
                     </apply>
                     <apply>
                        <times/>
                        <ci>d</ci>
                        <ci>R_2</ci>
                     </apply>
                  </apply>
                  <apply>
                     <times/>
                     <ci>g</ci>
                     <ci>R_2</ci>
                  </apply>
               </apply>
               <apply>
                  <times/>
                  <ci>beta_1</ci>
                  <ci>R_2</ci>
                  <ci>P_1</ci>
               </apply>
            </apply>
         </apply>
      </math>
   </component>
   <component xmlns="http://www.cellml.org/cellml/1.0#" name="R12">
      <variable name="R_12" units="dimensionless" initial_value="0" public_interface="out"/>
      <variable name="alpha_2" units="first_order_rate_constant" public_interface="in"/>
      <variable name="alpha_1" units="first_order_rate_constant" public_interface="in"/>
      <variable name="d" units="first_order_rate_constant" public_interface="in"/>
      <variable name="g" units="first_order_rate_constant" public_interface="in"/>
      <variable name="I_21" units="dimensionless" public_interface="in"/>
      <variable name="I_12" units="dimensionless" public_interface="in"/>
      <variable name="time" units="day" public_interface="in"/>
      <math xmlns="http://www.w3.org/1998/Math/MathML">
         <apply>
            <eq/>
            <apply>
               <diff/>
               <bvar>
                  <ci>time</ci>
               </bvar>
               <ci>R_12</ci>
            </apply>
            <apply>
               <minus/>
               <apply>
                  <minus/>
                  <apply>
                     <plus/>
                     <apply>
                        <times/>
                        <ci>alpha_2</ci>
                        <ci>I_12</ci>
                     </apply>
                     <apply>
                        <times/>
                        <ci>alpha_1</ci>
                        <ci>I_21</ci>
                     </apply>
                  </apply>
                  <apply>
                     <times/>
                     <ci>d</ci>
                     <ci>R_12</ci>
                  </apply>
               </apply>
               <apply>
                  <times/>
                  <ci>g</ci>
                  <ci>R_12</ci>
               </apply>
            </apply>
         </apply>
      </math>
   </component>
   <component xmlns="http://www.cellml.org/cellml/1.0#" name="P1">
      <variable name="P_1" units="dimensionless" initial_value="1" public_interface="out"/>
      <variable name="k_1" units="first_order_rate_constant" initial_value="1"/>
      <variable name="u" units="first_order_rate_constant" public_interface="in"/>
      <variable name="I_1" units="dimensionless" public_interface="in"/>
      <variable name="I_21" units="dimensionless" public_interface="in"/>
      <variable name="time" units="day" public_interface="in"/>
      <variable name="log_P1" units="dimensionless"/>
      <math xmlns="http://www.w3.org/1998/Math/MathML">
         <apply>
            <eq/>
            <apply>
               <diff/>
               <bvar>
                  <ci>time</ci>
               </bvar>
               <ci>P_1</ci>
            </apply>
            <apply>
               <minus/>
               <apply>
                  <times/>
                  <ci>k_1</ci>
                  <apply>
                     <plus/>
                     <ci>I_1</ci>
                     <ci>I_21</ci>
                  </apply>
               </apply>
               <apply>
                  <times/>
                  <ci>u</ci>
                  <ci>P_1</ci>
               </apply>
            </apply>
         </apply>
         <apply>
            <eq/>
            <ci>log_P1</ci>
            <apply>
               <log/>
               <ci>P_1</ci>
            </apply>
         </apply>
      </math>
   </component>
   <component xmlns="http://www.cellml.org/cellml/1.0#" name="P2">
      <variable name="P_2" units="dimensionless" initial_value="1" public_interface="out"/>
      <variable name="k_2" units="first_order_rate_constant" initial_value="1"/>
      <variable name="u" units="first_order_rate_constant" public_interface="in"/>
      <variable name="I_2" units="dimensionless" public_interface="in"/>
      <variable name="I_12" units="dimensionless" public_interface="in"/>
      <variable name="time" units="day" public_interface="in"/>
      <variable name="log_P2" units="dimensionless"/>
      <math xmlns="http://www.w3.org/1998/Math/MathML">
         <apply>
            <eq/>
            <apply>
               <diff/>
               <bvar>
                  <ci>time</ci>
               </bvar>
               <ci>P_2</ci>
            </apply>
            <apply>
               <minus/>
               <apply>
                  <times/>
                  <ci>k_2</ci>
                  <apply>
                     <plus/>
                     <ci>I_2</ci>
                     <ci>I_12</ci>
                  </apply>
               </apply>
               <apply>
                  <times/>
                  <ci>u</ci>
                  <ci>P_2</ci>
               </apply>
            </apply>
         </apply>
         <apply>
            <eq/>
            <ci>log_P2</ci>
            <apply>
               <log/>
               <ci>P_2</ci>
            </apply>
         </apply>
      </math>
   </component>
   <component xmlns="http://www.cellml.org/cellml/1.0#" name="memory_duration">
      <variable name="G" units="dimensionless"/>
      <variable name="g" units="first_order_rate_constant" initial_value="0.01" public_interface="out"/>
      <math xmlns="http://www.w3.org/1998/Math/MathML">
         <apply>
            <eq/>
            <ci>G</ci>
            <apply>
               <divide/>
               <cn cellml:units="first_order_rate_constant">1</cn>
               <ci>g</ci>
            </apply>
         </apply>
      </math>
   </component>
   <component xmlns="http://www.cellml.org/cellml/1.0#" name="kinetic_parameters">
      <variable name="beta_1" units="first_order_rate_constant" initial_value="1" public_interface="out"/>
      <variable name="alpha_1" units="first_order_rate_constant" initial_value="0.1" public_interface="out"/>
      <variable name="beta_2" units="first_order_rate_constant" initial_value="1" public_interface="out"/>
      <variable name="alpha_2" units="first_order_rate_constant" initial_value="0.1" public_interface="out"/>
      <variable name="a_1" units="first_order_rate_constant" initial_value="0.03" public_interface="out"/>
      <variable name="a_2" units="first_order_rate_constant" initial_value="1" public_interface="out"/>
      <variable name="d" units="first_order_rate_constant" initial_value="0.01" public_interface="out"/>
      <variable name="u" units="first_order_rate_constant" initial_value="0.5" public_interface="out"/>
   </component>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="S" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I1" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I2" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I12" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I21" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R1" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R2" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R12" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="P1" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="P2" component_2="environment"/>
      <map_variables variable_1="time" variable_2="time"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="S" component_2="P1"/>
      <map_variables variable_1="P_1" variable_2="P_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="S" component_2="P2"/>
      <map_variables variable_1="P_2" variable_2="P_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="S" component_2="R1"/>
      <map_variables variable_1="R_1" variable_2="R_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="S" component_2="R2"/>
      <map_variables variable_1="R_2" variable_2="R_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="S" component_2="R12"/>
      <map_variables variable_1="R_12" variable_2="R_12"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I1" component_2="S"/>
      <map_variables variable_1="S" variable_2="S"/>
      <map_variables variable_1="I_1" variable_2="I_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I2" component_2="S"/>
      <map_variables variable_1="S" variable_2="S"/>
      <map_variables variable_1="I_2" variable_2="I_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I12" component_2="S"/>
      <map_variables variable_1="I_12" variable_2="I_12"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I21" component_2="S"/>
      <map_variables variable_1="I_21" variable_2="I_21"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I1" component_2="P1"/>
      <map_variables variable_1="I_1" variable_2="I_1"/>
      <map_variables variable_1="P_1" variable_2="P_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I2" component_2="P2"/>
      <map_variables variable_1="I_2" variable_2="I_2"/>
      <map_variables variable_1="P_2" variable_2="P_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I21" component_2="P1"/>
      <map_variables variable_1="I_21" variable_2="I_21"/>
      <map_variables variable_1="P_1" variable_2="P_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I12" component_2="P2"/>
      <map_variables variable_1="I_12" variable_2="I_12"/>
      <map_variables variable_1="P_2" variable_2="P_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R1" component_2="I1"/>
      <map_variables variable_1="I_1" variable_2="I_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R1" component_2="I12"/>
      <map_variables variable_1="R_1" variable_2="R_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R2" component_2="I21"/>
      <map_variables variable_1="R_2" variable_2="R_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R2" component_2="I2"/>
      <map_variables variable_1="I_2" variable_2="I_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R1" component_2="P2"/>
      <map_variables variable_1="P_2" variable_2="P_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R2" component_2="P1"/>
      <map_variables variable_1="P_1" variable_2="P_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R12" component_2="I21"/>
      <map_variables variable_1="I_21" variable_2="I_21"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R12" component_2="I12"/>
      <map_variables variable_1="I_12" variable_2="I_12"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="S" component_2="kinetic_parameters"/>
      <map_variables variable_1="d" variable_2="d"/>
      <map_variables variable_1="beta_1" variable_2="beta_1"/>
      <map_variables variable_1="beta_2" variable_2="beta_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I1" component_2="kinetic_parameters"/>
      <map_variables variable_1="alpha_1" variable_2="alpha_1"/>
      <map_variables variable_1="a_1" variable_2="a_1"/>
      <map_variables variable_1="beta_1" variable_2="beta_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I2" component_2="kinetic_parameters"/>
      <map_variables variable_1="alpha_2" variable_2="alpha_2"/>
      <map_variables variable_1="a_2" variable_2="a_2"/>
      <map_variables variable_1="beta_2" variable_2="beta_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I21" component_2="kinetic_parameters"/>
      <map_variables variable_1="alpha_1" variable_2="alpha_1"/>
      <map_variables variable_1="a_1" variable_2="a_1"/>
      <map_variables variable_1="beta_1" variable_2="beta_1"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="I12" component_2="kinetic_parameters"/>
      <map_variables variable_1="alpha_2" variable_2="alpha_2"/>
      <map_variables variable_1="a_2" variable_2="a_2"/>
      <map_variables variable_1="beta_2" variable_2="beta_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R1" component_2="kinetic_parameters"/>
      <map_variables variable_1="alpha_1" variable_2="alpha_1"/>
      <map_variables variable_1="d" variable_2="d"/>
      <map_variables variable_1="beta_2" variable_2="beta_2"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R2" component_2="kinetic_parameters"/>
      <map_variables variable_1="alpha_2" variable_2="alpha_2"/>
      <map_variables variable_1="beta_1" variable_2="beta_1"/>
      <map_variables variable_1="d" variable_2="d"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R12" component_2="kinetic_parameters"/>
      <map_variables variable_1="alpha_1" variable_2="alpha_1"/>
      <map_variables variable_1="alpha_2" variable_2="alpha_2"/>
      <map_variables variable_1="d" variable_2="d"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="P1" component_2="kinetic_parameters"/>
      <map_variables variable_1="u" variable_2="u"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="P2" component_2="kinetic_parameters"/>
      <map_variables variable_1="u" variable_2="u"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="S" component_2="memory_duration"/>
      <map_variables variable_1="g" variable_2="g"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R1" component_2="memory_duration"/>
      <map_variables variable_1="g" variable_2="g"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R2" component_2="memory_duration"/>
      <map_variables variable_1="g" variable_2="g"/>
   </connection>
   <connection xmlns="http://www.cellml.org/cellml/1.0#">
      <map_components component_1="R12" component_2="memory_duration"/>
      <map_variables variable_1="g" variable_2="g"/>
   </connection>
</model>