RA92A recombinant protein as immunogen to protect cattle against tick challenge in Brazil and Uganda

In this study, the recombinant gut protein rRa92A produced in Pichia pastoris yeast cells was used to immunize cattle in two experiments, one in Brazil and the other in Uganda. In both experiments, the animals were intramuscularly (IM) injected with 200 µg of recombinant protein in Brazil on days 0, 30 and 51 and in Uganda on days 0, 30. Blood samples for sera separation were collected from different days in both experiments. These samples were analyzed by ELISAs. In Brazil, ticks collected from the animals during the experimental period were analyzed for biological parameters. At Uganda, blood was collected to assess blood parameters, clinical signs were recorded and adult tick (Rhipicephalus appendiculatus) counts were performed. All animals of the vaccinated groups were shown to produce antibodies, and it was not possible to detect an effect on Rhipicephalus microplus. All the clinical parameters were considered within the normal ranges for both the experimental and control groups in Uganda. Antibody absorbance was elevated after each immunization and remained high until the end of the experiments, remaining low in the control animals. The results of stall test carried out in Brazil using R. microplus tick showed efficacy of 21.95%. The rRa92A immunization trial experiments in Uganda showing a decrease of 55.2% in the number of engorged adult ticks, which was statistically significant (p<0.05). Assessment of the immunogenicity of Ra92A produced in the P. pastoris expression system in bovines is reported for the first time, and the protein acted as a concealed antigen.

Elevated antibody titers in Abdala vaccinees evaluated by Elecsys® anti-SARS-CoV-2 S highly correlate with UMELISA SARS-CoV-2 ANTI RBD, ACE-2 binding inhibition and viral neutralization assays.

SARS-CoV-2, a recently emerged coronavirus, is causing high morbidity and mortality worldwide since December 2019, posing an enormous health, social and economic problem. Obtaining effective treatments that can diminish deaths and sequelae and vaccines to slow or prevent viral transmission, and reduce disease severity and/or death are of utmost importance. Abdala is a Cuban vaccine based on the recombinant RBD subunit of the spike protein expressed in Pichia pastoris yeast. It demonstrated high efficacy (92.28 %) in phase III clinical trials for reducing transmission, and more than 90% effectiveness in reducing disease severity and mortality. Antibody titers were evaluated in 42 Abdala vaccinees using the Elecsys® Anti-SARS-CoV-2 S test. Fifteen days after immunization, sera from vaccinees showed high antibody titers (median of 1595 U/mL). The results obtained in this study also demonstrate correlation between the Cuban test UMELISA SARS-CoV-2 ANTI RBD used during the clinical trials and Elecsys® test results.

Cloning, expression in Komagataella phaffii, and biochemical characterization of recombinant sequence variants of Pseudomonas sp. S9 GDSL-esterase

Two recombinant Komagataella phaffii (formerly Pichia pastoris) yeast strains for production of two sequential variants of EstS9 esterase from psychrotolerant bacterium Pseudomonas sp. S9, i.e. αEstS9N (a two-domain enzyme consisting of a catalytic domain and an autotransporter domain) and αEstS9Δ (a single-domain esterase) were constructed. However, only one of recombinant K. phaffii strains, namely Komagataella phaffii X-33/pPICZαestS9Δ, allowed to successfully produce and secrete recombinant αEstS9Δ enzyme outside of the host cell. The purified αEstS9Δ esterase was active towards short-chain p-nitrophenyl esters (C2–C8), with optimal activity for the acetate (C2) ester. The single-domain αEstS9Δ esterase exhibits the highest activity at 60oC and pH 9.5. In addition, the enzyme retains 90% of its activity after 3 hour incubation at 70–90oC. What should be also noted is that αEstS9Δ esterase produced in the K. phaffii expression system has a much higher specific activity (0.069 U/mg of protein) than the recombinant EstS9Δ esterase produced in an E. coli expression system (0.0025 U/mg of protein) (Wicka et al., 2016, Acta Biochim Pol 63: 117–125. https://doi.org/10.18388/abp.2015_1074).

OPTIMAL CONDITIONS OF FERMENTATION OF THE PICHIA PASTORIS YEAST EXPRESSING THE RECOMBINANT PRES2-S PROTEIN (M-HBsAg) OF HEPATITIS B VIRUS (HBV)

The aim of this study is determination of optimal fermentation conditions of the Pichia pastoris yeast expressing the recombinant Pres2-S protein of hepatitis B virus (HBV). For this purpose we investigated the main factors influencing for the cultivation of recombinant strain of the yeast Pichia pastoris pPIC3,5-S-HBsAg - the composition of the nutrient medium, pH and dissolved oxygen (DO). As a result, by enzyme-linked immunosorbent assay (ELISA) the optimal concentration of methanol ≈1.0 %, which is the initiator and the only source of carbon for protein expression in the Mut+ phenotype Pichia pastoris yeast cells was determined. In the selected conditions at the end of the fermentation process, the wet biomass of yeast cells was 420 g/l.

Protective Malaria Vaccine in Mice Based on the Plasmodium vivax Circumsporozoite Protein Fused with the Mumps Nucleocapsid Protein

Plasmodium vivax is the most common species of human malaria parasite found outside Africa, with high endemicity in Asia, Central and South America, and Oceania. Although Plasmodium falciparum causes the majority of deaths, P. vivax can lead to severe malaria and result in significant morbidity and mortality. The development of a protective vaccine will be a major step toward malaria elimination. Recently, a formulation containing the three allelic variants of the P. vivax circumsporozoite protein (PvCSP—All epitopes) showed partial protection in mice after a challenge with the hybrid Plasmodium berghei (Pb) sporozoite, in which the PbCSP central repeats were replaced by the VK210 PvCSP repeats (Pb/Pv sporozoite). In the present study, the chimeric PvCSP allelic variants (VK210, VK247, and P. vivax-like) were fused with the mumps virus nucleocapsid protein in the absence (NLP-CSPR) or presence of the conserved C-terminal (CT) domain of PvCSP (NLP-CSPCT). To elicit stronger humoral and cellular responses, Pichia pastoris yeast was used to assemble them as nucleocapsid-like particles (NLPs). Mice were immunized with each recombinant protein adjuvanted with Poly (I:C) and presented a high frequency of antigen-specific antibody-secreting cells (ASCs) on days 5 and 30, respectively, in the spleen and bone marrow. Moreover, high IgG titers against all PvCSP variants were detected in the sera. Later, these immunized mice with NLP-CSPCT were challenged with Pb/Pv sporozoites. Sterile protection was observed in 30% of the challenged mice. Therefore, this vaccine formulation use has the potential to be a good candidate for the development of a universal vaccine against P. vivax malaria.

The analysis of the polyamine oxidase genes in the methylotrophic yeast Komagataella phaffii

Polyamines are present in all living cells and regulate a wide range of biological processes. In Saccharomyces cerevisiae the polyamine oxidase Fms1p converts spermine to spermidine and 3-aminopropionaldehyde, which is necessary for the synthesis of pantothenic acid and hypusination. This paper shows that S. cerevisiae FMS1 gene orthologs are present in all major representatives of the Saccharomycotina subdivision, but their copy numbers are different. In the Komagataella phaffii (Pichia pastoris) yeast, two polyamine oxidase genes (KpFMS1 and KpFMS2) were identified, and the regulation of their promoters activity was studied.

Elucidation of molecular functions of human tumor suppressor protein 101F6 by reconstitution into phospholipid bilayer nanodiscs

A candidate human tumor suppressor gene 101F6 product was expressed successfully in Pichia pastoris yeast cells. The purified 101F6 protein was successfully incorporated into phospholipid bilayer nanodiscs with different sizes by employing two reconstitution methods; self-assembly and reconstitution into the preformed empty nanodisc. The reconstituted 101F6 protein could be reduced with ascorbate quickly and was very stable even at ambient temperatures.