# An Overview of the Public Health Challenges in Diagnosing and Controlling Human Foodborne Pathogens
## 4 Diagnostic Approaches of Foodborne Pathogens
### Methods Based on Nucleic Acids
#### 4.2.3 Diagnostic Immunology  
Since the advent of immunologic diagnostic techniques and their widespread use, immunological diagnostic tools have evolved tremendously from their initial invention into the present day; they have established a hegemonic status in the fields of biological science, food science, and clinical medicine. In immunological detection, specific antibodies (polyclonal antibodies or monoclonal antibodies) bind to specific antigens, which is known as an antibody-antigen interaction [158; 159; 160; 161]. The detection of microbial toxins and pathogens in food has been accomplished with the use of several antibodies. Specificity of the antibodies is the most important factor in determining the appropriateness of the antigen-antibody combination [146]. A polyclonal antibody, which is made from either rabbit or goat serum, contains multiple antibodies of varying biological origins and levels of specificity. When identifying molecules with precision, monoclonal antibodies are frequently more helpful than polyclonal antibodies. Immunological detection of microbial contamination has become more specific, sensitive, reproducible and reliable with the development of monoclonal antibodies [162]. There are two immunologically based techniques that are being used increasingly for the detection of foodborne microorganisms: lateral flow immunoassays and enzyme-linked immunosorbent assays (ELISA). Enzyme-Linked Immunosorbent Assay (ELISA)  
In terms of a diagnostic biochemical test, ELISA can be regarded as a sensitive and specific method that does not require the use of elaborate or expensive instruments for the detection, quantification and analysis of analytes [163; 164; 165]. Although conventional ELISA is widely utilized in scientific research and testing organizations today and is regarded as an effective technique for the identification of viruses and antibodies, this conventional method requires skilled operation techniques and it is also extremely time-consuming [166; 167]. Therefore, the researchers modified the conventional methodology in order to carry out their study. A variety of anti-NoV antibodies were tested by [PERSON] et al. [168] using an indirect ELISA, which they developed to evaluate the antibodies. Throughout the entire testing process, two hours were needed to complete the testing of the entire range of unknown antibodies. Within and between the tests, there was no difference in the coefficients of variance, which both fell under 10%. In a sandwich-ELISA based on the _Salmonella enteritidis_ antigen, [PERSON] et al. [169] successfully found 6 CFU/mL of _Salmonella enteritidis_ in milk after 10 h of enrichment. A wax-printed paper-based enzyme-linked immunosorbent assay based on microfluidic paper-based analytical equipment was developed by [PERSON] et al. [170] in less than 3 hours and a sample volume of only 5 uL was required for detection. In the case of _Eherichia coli_ O157:H7, the limit of detection was \(10^{4}\) CFU/mL. There are many advantages of ELISA tests, including simplicity, high specificity and sensitivity, high efficiency (since multiple tests can be conducted simultaneously), and cost-effectiveness (because reagents are cheap) [171]. However, it is labor-intensive and expensive to make antibodies, and expensive growth mediums are necessary to obtain a specific antibody. Moreover, there is a risk of false positives or negatives due to insufficient blocking of the antigen-immobilized microtiter plate surface [171]. Immunomagnetic Separation Technology (IMS)  
As one sample preparation technique of pre-concentrating food samples, IMS has been proposed to rapidly and precisely remove and concentrate target germs from challenging food substrates [172; 173]. Generally, superparamagnetic particles are chemically modified, and then they are combined with antibacterial proteins made from immunomagnetic beads separation, which then can be used to identify and capture the target bacteria in the samples that are being tested according to the main theory [174; 175].