فصلنامه دنیای میکروب ها
سال پانزدهم شماره 3 (پیاپی 52، پاییز 1401)

Shigellosis is an infectious disease caused by Shigella dysenteriae and threatens the lives of millions of people worldwide annually. IpaB protein, which is part of the Shigella type III secretion system (T3SS), it can elicit a favorable immune response against the bacterium. The aim of this study is experimental evaluation of the immunogenicity of a recombinant protein containing immunogenic regions of IpaB as a subunit recombinant vaccine candidate against Shigella dysenteriae.

The gene encoding immunogenic protein that cloned into pET28a expression vector was transformed in the bacterial host E.coil strain Rosetta (DE3) and induced by IPTG. The purified protein was achieved using nickel chromatography column and injected into guinea pigs for immunization. The produced antibody titer was assessed by indirect ELISA assay and finally animal challenge was performed using the Sereny test in guinea pigs.

A 36 KDa band as IpaB protein was observed in SDS-PAGE which was confirmed by western blot. The immunological analyses showed production of high titer of specific anti-IpaB antibody (1:102,400) in immunized Guinea pig. The absence of any keratoconjunctival inflammation in immunized guinea pigs in Sereny test indicated high level protection against  virulent Shigella dysentriea.

The results showed that IpaB can elicit high titer of antibody and protection against Shigella dysentriae in Guinea pigs.

Small ruminant plague is one of the most economically important pathogens in sheep and goats caused by morbilli viruses. Protein H is one of the major proteins for immunity against PPRV. The aim of the present study was to clone and express the H gene of this virus by the baculovirus expression system.

H gene was amplified by RT-PCR and specific primers and then cloned into pFastBac Dual plasmid. The recombinant vector with the gene was transferred to the DH10Bac host cell. By transfection Sf9 cell with recombinant vector, its expression and  characteristics were evaluated by SDS-PAGE, western blotting and Bradford methods.

The H gene was amplified using specific primers from the PPR virus genome and the   specific band was obtained. Cloning of the H gene on the pFastBac Dual vector and baculovirus genome was proved with PCR and enzymatic digestion. By transfection the recombinant vector into Sf9 cells and performing sequential passages, the recombinant protein was shown to be completely pure and specific using SDS-PAGE, Western blotting and Bradford methods. The expression level of this gene was obtained 218 µg/ml.

Considering the production of an appropriate amount of recombinant H protein, this protein can be a suitable candidate for the production of recombinant vaccine against PPRV.

Pasteurella (P.) maltocida is the cause of pasteurellosis. Animals and sometimes humans are involved with this bacterium. The aim of this study was to evaluate immune responses in sheep vaccinated with inactive antigen along with alum and AbDNA adjuvant by tracking IgG and cytokine levels on serum samples.

Sheep were immunized with two doses of inactivated vaccine with formalin at an interval of 2 weeks. Alum and DNA of P.maltocida serotype A strain were used as an adjuvant. One milliliter of immunogen was inoculated subcutaneously to the animals. After  ELISA design, immune response was evaluated by measuring specific IgG antibody titer and TNF-α measurement on serum samples and lymphocyte cell culture.

The antibody titer in the group receiving DNA was higher than the group receiving Alum and the control groups. The highest antibody level (1.463) was related to the FIV-AbDNA group in the fourth week. In the FIV-Alum group, the highest titer was 1.054, which indicates a weaker immune response compared to the DNA group. AbDNA also increased the production of TNF-α. TNF-α in immunized animals increased significantly compared to the control groups. The highest titer of TNF-α (1.44) was related to the FIV-AbDNA group on the serum sample.

P.maltocida antigen together with bacterial DNA as an adjuvant is an alternative candidate for making new vaccines against P.maltocida. Considering the ability of AbDNA to   create immune responses through the release of different cytokines, it is suggested to evaluate different types of cytokines.

Nayband Gulf is subjected to oil pollution due to the proximity to Assaluyeh industrial region. Prolonged exposure to contaminants affects the microbial population and shifts the population to the predominance of oil-degrading microbes. In this study, we  investigate the microbial diversity in Nayband Gulf waters and predict the genes involved in aromatic hydrocarbon degradation under aerobic and anaerobic conditions.

Phenol-chloroform method was performed for extracting DNA from the Nayband Gulf water sample. Extracted DNA sequencing was performed by new generation  sequencing technique. Then 16S rRNA gene-based amplicon sequencing was analyzed. Functional genes involved in the degradation of aromatic hydrocarbons under aerobic and anaerobic conditions were predicted from 16S rRNA gene sequences.

Our findings indicate that aromatic hydrocarbons contamination in Nayband Gulf water resulted in the enrichment of Oceanospirillales (24.67%), Cellvibrionales (28.95%), SAR11 clade (20.97%), Rhodobacterales (6.17%), Rhodospirillales (7.12%) and Flavobacteriales (5.50%).  Alphaproteobacteria (26.18%) and Gammaproteobacteria (42.23%) had the highest percentage. According to Phylogenetic Investigation of Communities by Reconstruction of Unobserved States, the genes involved in degradation of naphthalene under anaerobic conditions were most abundant in the sample.

The results of this study showed that long-term exposure to oil pollution and oil spills affects the microbial population. The microbial population of Nayband Gulf region, due to its proximity to the South Pars oil & gas region and the entry of oil pollutants into the water, has caused the domination of petroleum hydrocarbons degrading bacteria.

Actinobacteria are very important in the world in terms of the production of metabolites with various biological effects. This study was conducted with the aim of investigating the toxicity of the fermented extract obtained from Actinobacteria isolated from some biological resources of Iran on Artemia urmiana. These isolates were deposited in University of Tehran Microorganisms Collection (UTMC).

Forty-eight -76°C actinobacterial isolates were revived using ISP2 agar culture medium. Two bacterial discs were inoculated in ISP2 broth medium as a pre-cultivation medium. After 48 hours, 10 ml of the liquid was inoculated into the fermentation culture medium and heated for 7 days in a shaker incubator with 180 rpm, temperature of 28°C and pH of 7.2 ± 0.2. The fermentation broth was extracted using ethyl acetate, the solvent was evaporated using a low-pressure rotary evaporator. The toxicity of fermentation broth extracts was assayed against    40-hour Artemia urmiana nauplii.

According to the toxicity classification, among the all 48 isolates, 64.58% were highly toxic, 22.91% were moderate toxic, and 12.5% were in the low toxicity compounds group.

The results showed that more than half of the tested extracts had very high lethality on Artemia urmiana in a short time. Comparing the LC50 and LT50 values of the extracts with  similar studies, it was found that these extracts have a significant biological activity and can be used as a rich source in the production of metabolites with proper biological effects.

 Nowadays, antimicrobial peptides produced from insects are  considered for their antibacterial activity against pathogens and the fewer side effects. The aim of this study is a bioinformatics analysis of attacin1a as an antibacterial compound and the   investigation of its physicochemical properties for laboratory research based on the production of drug delivery carriers and vaccine design.

 The sequence of attacin1a gene belonged to T. molitor, was extracted in FASTA format from the NCBI database; www.ncbi.nlm.nih.gov. The Molecular weight,  similarity and physicochemical characteristics were investigated in the attacin1a and their  homologous peptides. In addition, the second and tertiary structures of the attacin1a were predicted using bioinformatics software’s, and the function and immunogenicity of the peptide were studied.

 Bioinformatics studies showed that the amino acid sequences of the attacin1a were  conserved in the central and c-terminal regions between 10 members of the suborder Polyphaga. The assessment of structural and biochemical properties showed that the attacin1a structure       contains 51% of non-polar amino acids with a disorder index of 61% and flexibility of 53%. The second structure of attacin1a consisted of 52.60% Random coils, 21.43% beta-strands and 21.43% alpha helices. The prediction of the tertiary structure in the Phyre2 showed 32% confidence and 31.1% identity to a beta-immunoglobulin protein (d2aw2a1). This peptide doesn’t have a high ability to stimulate the immune system.

The abundance of beta strands in the attacin 1a structure increased the molecule's stability and its ability to cross through the cell membrane in bacteria.