The previous experiment  demonstrated how different immunizing schedules shape the interaction between host and parasite. The image below  depicts three states of  a two-CA system: Isolation, encroachment and immunity.  CA-2 immunity is manifested by two features: 1. CA-2 thrives and  kills CA-1. We may wonder what happens to the system after eliminating the parasite?   In the present experiment, both CA interact and  I = { +,  +}. CA-1 was  then killed at rising times.

The graphs below depict the change of CA-2 parameters following CA-1 killing at rising times. In 11 instances (=18%)  CA-1 killing was followed by CA-2 death, which is somewhat unexpected. One might assume that parasite removal ought to save the host.  Apparently the relationship between CA-1 and CA-2 involves more than just a one way exploitation. In most cases both CA gained.

When CA-2 dies soon after CA-1 is killed it indicates, that during their brief encounter CA-2 benefited from a vital substance produced by CA-1  In 18% of such encounters CA-2 developed an absolute  dependency on the CA-1 product. In the rest  CA-2 may have also benefited, yet remained independent and survived CA-1 killing.

Each curve starts with the value of an isolated CA-2,  marked by an A, and ends with a value observed in an independent CA-2 marked by a B. An isolated (or virgin) CA-2 did not interact with CA-1. while the independent CA-2 interacted with CA-1 until its killing or its own  death at t = 62 (see the image above) and then became independent..

Cell count proceeds through three phases:
I Partial dependency on CA-1. Apparently CA-1 secreted a trophic factor which made the CA-2 bigger. Since after  CA-1 killing the factor is missing, CA-2  shrunk.
II Independence:  CA-2 remains big even when CA-1 was killed.
III Mounting dependence: CA-2 size declines until becoming smaller than that of an isolated CA-2 (B)

Production follows a similar course, only health is different.  From the beginning CA-2 becomes healthier (more efficient). Later its health declines and becomes  lower than that of an isolated CA-2 (B).  On t = 62 the immunized CA-2 kills  CA-1  ( see  upper image). Its  on going health deterioration  results from a factor produced by CA-1 which after its death is missing.

Below are two representative CA-1.

Symbiosis and Parasitism

The relationship  between the two CA  involves more than just  a  one way exploitation. The declining parameters indicate that both CA benefit from this relationship. Parasite and symbiont are not as distinct as is commonly viewed.   Each host parasite relationship involves also symbiosis, which explains how parasites turn into symbionts. By a gradual shift of dependencies between them and their host. Lyn Margulies believes that the  symbiosis between unicellular organism promoted  the transition from prokaryotes to eukariotes. Two unicellular organisms intended to exploit each other, but established a mutual relationship similar to that described here. In the end one was engulfed by the other  and became its nucleus.

injurystate[1, j, mm, f[[1,1]], 27, 0]; effect[1, 30 + 2 sa[[2]]]; effect[2, 15 + sa[[1]]]; age[[no, f[[no, 1]] ]] = 0;

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