The fossil record shows that shrimp have been close to their current form for upwards of 350 million years.   Clearly shrimp are high evolved and have developed a variety of mechanisms to ensure survival.    Shrimp are invertebrates.   They have no spine and their skeletons are outside of their bodies, unlike vertebrates that have an internal spinal column and whose skeletons are internal.   Vertebrates have evolved highly complex immune systems.   They have many different types of while blood cells and produce a variety of types of proteins, referred to as antibodies, and they can remember (known as an amnestic response) for the life of the animal an exposure to a pathogen, mounting a rapid immune response.    Shrimp, as with all invertebrates, have a very small number of different types of white blood cells and have no amnestic response.   They produce a very limited number of proteins, termed lectins, that react generically with the cell wall sugars of pathogens.  

 

Vertebrates have a specific immune response, invertebrates do not.   Their response is on-specific.    Many substances have been reported to induce this response with a great deal of variability as to effectiveness.  They cannot be immunized.   While there are some that will tell you that they can indeed make shrimp immune to specific viruses, etc. this is not through the immune system.   RNA interference (RNAi) acts by interfering at the gene level with gene expression.   It can be used to turn off the ability of a cell to be infected or once infected to be taken over by a virus.   This effectively prevents the disease process. 

 

MBXC was developed at a time when we knew little about what was going on inside of the shrimp.   It was tested extensively under controlled laboratory conditions and it was found to "protect" shrimp in a very broad, generic manner against TSV, WSSV, various vibrios including the etiologic agent of EMS or AHPNS.   This benefit is short lived although the natural diet more than likely reenforces it to some extent.    It was used in the field and found, when applied as a single feeding during PL production (the animals ingest the material much as they would yeast-which contain a different cell wall component that is thought to have similar properties) was found to have a benefit in the field.   This benefit is not such that one could claim that it is solely as a result of non-specific immune stimulation.   The high free nucleotide content in MBXC is more than likely a very important if not the primary component of the observed impacts.   

 

Extensive field testing has shown that it is a cost effective tool and that it can have a favorable impact on growth, growth rates, and other factors relevant to profitability.    This has been borne out through field tests in several countries on billions of shrimp.    This is a tool much as other nutrients are.   It does not function in a void and it will do little if anything to help animals that are seriously stressed, carrying high loads of pathogens and in general not fit for optimum production.    If the animals are properly fed, held under relatively stress free conditions, and not carrying high loads of pathogens then the nutrients can have a positive impact.