The development of molecular biology techniques will help in the diagnosis of salmonellosis and other pathologies in birds.
Las new techniques developed for diagnosis of salmonellosis in birds, they include a wide range of systems and processes that have been achieved to determine exactly what species it is in infections salmonella and differentiation between field strains and vaccine strains.
They exist semi-automatic systemskits based on biochemical characteristics and sensitivity/resistance to certain antibiotics, immunological techniques, serological methods, etc.
Among all of them, which are being worked on with greater intensity, due to their great potential to overcome the limitations of traditional techniques, are the so-called techniques of molecular biologyemphasizing especially those based on polymerase chain reactionknown as PCR by its abbreviation in English.
They were used classically techniques based on susceptibility/resistance to certain antibiotics for the identification of vaccine strains.
Characteristics of sensitivity or resistance to certain antibiotics are acquired characteristics vaccine bacteria in the process of modifying its properties immunogenicity, excretion and/or attenuation.
- However, these properties are purely phenotypic and lack precision which may have a molecular technique based on the identification of genetic material.
Salmonellosis is one of the zoonoses that has the greatest impact on human health. causing gastrointestinal processes that can be of varying severity and can cause serious problems in infected people.
The infection It is usually produced by a company consumption food of animal origin and especially by consuming contaminated eggs and poultry meat with insufficient culinary preparation.
In order to reduce the prevalence of salmonellosis in birds as much as possible and with it the subsequent transmission to humans, the European Union established guidelines for the control of this disease, which subsequently led to National Programs for Salmonella Control (PNCS) where all measures are aimed at reducing Salmonella in birds.
Currently the diagnosis is salmonella in birds, it is performed using a standard-based methodology ISO 6579 and which consists of analyzing different samples using different culture media that allow us to do this isolation and subsequent identification of the strain salmonella.
Based on strain identification Salmonella Zoonotics (Salmonella Enteritidis o Salmonella Typhimurium) is essential identify the vaccine strain if live vaccines were used.
This analytical procedure, if based on susceptibility to certain antibiotics, may present inaccuracies (field strains with the same antibiotic profile), interpretive limitations and excessive time to obtain a result, taking into account that the poultry farmer needs maximum speed determine the existence of a positive field.
Diagnosis by PCR It offers numerous advantages over other techniques, of which the main ones stand out:
- AND increased sensitivity (the ability to distinguish at the molecular level between different bacterial strains)
- More speed especially the implementation of high-impact actions on farms sampled in national salmonella control programs is a very important aspect in obtaining results.
PCR techniques have evolved from traditional PCR to real-time or RT (Real Time) PCR.
Real-time PCR is currently the most widely used for the diagnosis of numerous major diseases in animal health.
Unlike the traditional method – in which we work only on a qualitative level and to obtain results it is also necessary to combine other techniques (e.g. electrophoresis) Real-time PCR enables continuous monitoring and quantification of datawithout any subsequent modification.
One of the main applications of this technique in the diagnosis of salmonellosis in birds is the possibility distinguish between the strains present in various registered vaccines such as the Calier vaccine Primary salmonella E y The first Salmonella T and field tribes.
Based on this technology, different DIVA diagnostic test (Differentiating Infected from Vaccinated Animals), which, in addition to this distinction between vaccine and field strains, also allows us to perform excretion control vaccine strains, as well as detect their presence in different types of samples.
- This is all very helpful do follow-up actions vaccinations carried out on farms.
The continued progress and development of these molecular biology techniques will provide the tools to make this possible they will be very useful in everything related diagnosis of salmonellosis in birds, as in others important pathologies in poultry farming.
CALIER WORK EXACTLY ON THE DEVELOPMENT OF THESE DIAGNOSTIC TECHNIQUES
This will be made possible by the technology itself and the use of transport formats (FTA cards). speed up diagnosis and use techniques maximum accuracy both for species identification Salmonella regarding the distinction between vaccine strains and field strains.
In this sense, in addition to the already commercial PCR (Kylt SE DIVA 2) for strain differentiation Salmonella enteritis Priimun Salmonella E, Calier has developed – in collaboration with the biotechnology company Genetic PCR solutions – PCR for vaccine strain differentiation Salmonella Typhimurium contained in Priimmun Salmonella T.
This PCR is based on detection of diverse and exclusive regions of the genome bacteria, which was achieved by comparison with sequences reported in NCBI (National Center for Biotechnology Information), which includes more than 500,000 sequences another for Salmonella spp.
The possibility of differentiation is in accordance with the guidelines expressed in national control programs salmonella which require that attenuated vaccines have an adequate method for their bacteriological differentiation.
