Browsing tag: Salmonella

Typowanie bakteriofagowe w diagnostyce pałeczek Salmonella Enteritidis występujących w Polsce

Phage typing in the diagnostic of Salmonella Enteritidis occurring in Poland
B. Dera-Tomaszewska, E. Tokarska-Pietrzak

1. Wprowadzenie. 2. Typowanie bakteriofagowe. 3. Schematy typowania bakteriofagowego pałeczek Salmonella. 4. Typy bakteriofagowe Salmonella Enteritidis występujące w Polsce. 5. Podsumowanie

Abstract: Phage typing has a long history with regard to the differentiation of Salmonella serovars of human and animal origin. This method provides the fast and cheap characterization of frequent serovars on the sub-serovar level and is especially useful for primary epidemiological analysis before investigation by other, more expensive molecular techniques. Since the discovery of bacteriophages many different Salmonella typing schemes have been developed. More than one typing scheme may have been developed for a serovar. Several phage-typing schemes have been published for Salmonella Enteritidis. The most widely used is that of Ward et al. In Poland a different typing scheme is used − the Lalko et al. scheme. It employs eight typing phages for differentiation more than 20 phage types. Basing on the results of Salmonella Enteritidis phage typing, which has been conducted in Poland for many years, it can be noted that Salmonella Enteritidis infections reported in our country during the last fifty years were associated with two serious epidemics. Among the strains isolated during the first epidemic, phage types 2, 5, 7, 8 and 12 were predominant and the great majority of the strains were represented by types 8 and 5. Phage types 1, 6 and 7 were found to be dominated during 27 years of the second Salmonella Enteritidis epidemic in Poland. The strains of type 7 were the most numerous ones. The results of phage typing indicate that sources of infections of these two Salmonella Enteritidis epidemics are quite different. However, a relationship between them exists: Salmonella Enteritidis type 7 organisms occur in both. During the first epidemic they were isolated in a relatively small percentage and only from humans. The great majority of sources of Salmonella Enteritidis infections associated with the second epidemic were dominated by them. They were also prevalent in human isolates. Generally, during the last 27 years, no significant changes in the distribution of Salmonella Enteritidis phage types in Poland have been observed. Although, it is noteworthy that except the same, permanent phage types continuously existing in the environment, the new types start to appear. They can suggest an appearance of new sources of Salmonella Enteritidis infections, unknown yet in our country, which is very possible as a result of effective elimination of currently existing ones.

1. Introduction. 2. Phage typing. 3. Salmonella phage typing schemes. 4. Salmonella Enteritidis phage types occurring in Poland. 5. Summary

Immunoprofilaktyka zakażeń Campylobacter

Anti-Campylobacter immunoprophylaxis
P. Łaniewski, E. K. Jagusztyn - Krynicka

1. Charakterystyka patogenu i epidemiologia zakażeń. 2. Objawy chorobowe i źródła zakażeń. 3. Szczepionki anty-Campylobacter. 4. Podjednostkowe szczepionki anty-Campylobacter skonstruowane z użyciem atenuowanych szczepów S.enterica. 5. Podsumowanie

Abstract: Campylobacter jejuni is currently recognized as a major cause of food-borne human gastroenteritis worldwide. In developed countries the majority of Campylobacter infections are associated with the consumption of undercooked poultry meat. Although a  disease lasts only several days and is very often self-limiting, campylobacteriosis constitutes a serious medical and socioeconomic problem. In patients, especially from developed countries, who have not encountered the pathogen before the infection can result in severe gastroenteritis accompanied with long-lasting bloody or mucus diarrhea. Moreover, C. jejuni can cause septicemia in immunocompromised individuals or induce autoimmune neurological disorders. Rapidly increasing antibiotic resistance of Campylobacter strains compels us to develop alternative therapeutic strategies. Implementation of immunoprophylaxis for humans or chickens seems to be the most effective strategy to decrease the number of human infections. Subunit vaccines are the safest, but mildly immunogenic, prophylactic method therefore, heterologous antigens are frequently delivered to a host by special delivery vectors i.e. attenuated Salmonella strains, to induce protective immune response. Avirulent Salmonella strains were also successfully used as a carrier to construct anti-Campylobacter subunit vaccines. Up till now, only several Campylobacter genes encoding immunogenic proteins: Peb1A, CjaA, Pal, Cj0420 and bacterioferritin, were cloned in Salmonella cells and the immune response and protection efficiency of constructed vaccine were determined on animal models. Here, we discuss the recent developments in the field of Salmonella-based anti-Campylobacter vaccines.

1. Pathogen characteristics and infection epidemiology. 2. The symptoms and source of infections. 3. Anti-Campylobacter vaccines. 4. Anti-Campylobacter subunit vaccines constructed with attenuated S.enterica cells. 5. Conclusions

Konstrukcja szczepionek podjednostkowych z wykorzystaniem komórek Salmonella enterica jako nośnika heterologicznych genów

Subunit vaccine construction using Salmonella enterica cells as a carrier of heterologous genes
P. Łaniewski, E. K. Jagusztyn - Krynicka

1. Salmonella jako idealny nośnik heterologicznych antygenów. 2. Atenuacja komórek S.enterica. 3. Stabilność utrzymania transgenu. 4. Poziom ekspresji transgenu. 5. Lokalizacja antygenu a typ odpowiedzi immunologicznej. 6. Podsumowanie

Abstract: Salmonella enterica strains are widely employed as a live delivery vector for subunit vaccine construction. Vaccine strains must be safe but still immunogenic; therefore, it is crucial to obtain a proper balance between the attenuation and the reactogenicity of the constructed strains. Salmonella strains used in immunoprophylaxis are mainly constitutively disrupted in genes involved in auxotrophy, virulence or regulation. A novel promising concept of the Salmonella-based vaccine design is a regulated delayed attenuation in vivo combined with a delayed antigen expression system. Using this approach bacteria display features of a wild-type strain at the time of oral vaccination to effectively colonize the lymphoid tissue and the fully attenuated phenotype after host tissue colonization. Expression of heterelogous genes in Salmonella cells is mainly achieved by introducing recombinant plasmids harboring gene of interest. Alternatively, a transgene can be integrated into a chromosomal DNA. Diverse strategies were developed to control plasmid maintenance and foreign gene expression. Among them the most frequently used are the balanced-lethal and toxin-antidote systems or operator-repressor titration technology. Overproduction of a recombinant protein often causes a metabolic burden in vaccine cells resulting in the loss of their viability. To overwhelm the problem, the transgene expression is kept under control of an in vivo inducible promoter or a promoter which activity is regulated by appropriate small molecules. Alternatively, plasmids with a regulated copy number or a delayed antigen synthesis system have been employed by various research groups. Localization of an antigen in a carrier cell is also critical for the strength and type of immune response. A programmed lysis of carrier cells is used to deliver the antigen to host immune cells. Moreover, Salmonella is used to carry DNA vaccines. Here, we review the latest strategies in the design of Salmonella-based subunit vaccines.

1. Salmonella as a perfect carrier of heterologous antigens. 2. Attenuation of S.enterica cells. 3. Transgene stability. 4. Transgene expression level. 5. Antigen localization and the type of immune response. 6. Conclusions