ELISA = Enzyme-linked Immunosorbent Assay

The ELISA is a biomolecular technique to detect pathogen-specific antibodies or antigens by means of an antigen-antibody reaction. We use indirect ELISAs to detect antibodies against various bacteria and viruses.

Significance/ advantages and disadvantages:

We employ highly sensitive and highly specific in-house developed ELISA`s as well as commercial kits. In order to validate positive results, we cooperate with other laboratories and, if possible, have questionable results checked with other methods. With this examination method, there is a risk of immunological cross-reactions, which can cause a non-specific positive result. In addition, the detection of antibodies against a pathogen is not to be equated with an acute infection, but rather proof that the animal's immune system has had contact with the pathogen.

IFA = Immunfluoreszenz - Assay

The indirect IFA is an examination method for the detection of pathogen-specific antibodies by means of an antigen-antibody reaction.

Significance/ advantages and disadvantages:

The significance as well as the advantages and disadvantages of the IFA are comparable to those of the ELISA. However, electronic quantification is more difficult with IFA.

Culture and MALDI-TOF MS = Matrix-Assisted Laser Desorption-Ionisation with Time-Of-Flight analysis and subsequent Mass Spectrometry

Cultural cultivation is a direct detection method, especially for bacterial pathogens, but also for fungi.

Significance/ advantages and disadvantages:

The cultivation of bacteria and their determination in the MALDI-TOF MS has advantages and disadvantages like any other examination method. Given that this is a direct pathogen detection, the significance of this examination is very good if the samples are taken correctly. It can give an overview of the bacterial flora of the sampled localization and represents the only possibility of a complete resistance determination of a bacterium.

Because of the dependence on the reproduction rate of the pathogens, the cultural examination takes a comparatively long time. The accuracy of the image of the germ flora in a culture depends not only on correct sampling, but also on the correct selection of the culture medium and the cultivation conditions (temperature, aerobic, anaerobic, microaerophilic, etc.).

Microscopy

Microscopic examination is used as a direct detection method, especially in parasitology.

Significance/ advantages and disadvantages:

As this is a direct pathogen detection method, the informative value of this examination is very good if the samples are taken correctly. The parasites are diagnosed on the basis of their morphology and movement patterns.

Microbiome analysis

The term microbiome refers to the totality of all microorganisms (bacteria, fungi, viruses, protozoa, etc.) that colonise a living organism. The most diverse microbiome and the most frequently studied microbiome is that of the intestine. For a microbiome analysis, the entire DNA is isolated from a faecal sample and completely sequenced using NGS shotgun sequencing. The sequences obtained are then analysed bioinformatically. With the help of this procedure, several hundred species can be identified and their percentage share in the examined sample can be determined.

Significance/ advantages and disadvantages:

The gut microbiome influences a variety of physiological processes, the nervous system, the immune system and many other factors and is therefore more decisive for the phenotype of the animal studied than its genotype. In addition, the microbiome can constantly change due to various factors. It therefore makes sense, for example, to analyse the microbiome of the test animals at the beginning of a study and to do this at regular intervals in long-term studies. In comparative studies of genetically modified animals and their wild type, a microbiome analysis can show whether the phenotypic changes found are caused by induced changes in the microbiome. Changes in housing conditions, feed or the use of medicines can also lead to a change in the microbiome; here too, a microbiome analysis can show the influence on experiments.

NGS = Next Generation Sequencing

The term Next Generation Sequencing (NGS) is used to describe gene analysis methods that can be used to sequence a very large number of DNA molecules in parallel in a high-throughput process. It represents a technological advancement of the original Sanger sequencing, but is faster, more accurate and less expensive than it. NGS enables the rapid sequencing of entire genomes using shotgun sequencing or the targeted sequencing of individual or multiple genes using panel sequencing.

Significance/ advantages and disadvantages:

Compared to conventional Sanger sequencing, NGS offers higher sensitivity, a lower error rate, more sequence information, and an improved possibility to discover sequence variants. With a higher number of targets, it is also faster and more cost-effective than conventional methods. NGS technology can be used effectively for a wide range of diagnostic questions: With the help of panel sequencing, for example, a large number of pathogens can be detected simultaneously specifically and beyond doubt.

PCR= Polymerase Chain Reaction

PCR is an examination method in which the DNA or RNA of a specific pathogen is detected. For this purpose, a short, precisely defined sequence section (target, amplicon) of the pathogen's DNA is amplified. The PCR product is then detected qualitatively or quantitatively.

Significance/ advantages and disadvantages:

Since this is a direct pathogen detection, the significance of this examination is very good if the sample is taken correctly. PCR is a very sensitive examination method that can detect the smallest amounts of pathogens. The accuracy of the result also depends on correct sampling.