Molecular Analysis of Dihydropteroate Synthase Gene Mutations in Pneumocystis jirovecii Isolates among Bulgarian Patients with Pneumocystis Pneumonia

Pneumocystis jirovecii pneumonia (PCP) is a significant cause of morbidity and mortality in immunocompromised people. The widespread use of trimethoprim-sulfamethoxazole (TMP-SMZ) for the treatment and prophylaxis of opportunistic infections (including PCP) has led to an increased selection of TMP-SMZ-resistant microorganisms. Sulfa/sulfone resistance has been demonstrated to result from specific point mutations in the DHPS gene. This study aims to investigate the presence of DHPS gene mutations among P. jirovecii isolates from Bulgarian patients with PCP. A total of 326 patients were examined via real-time PCR targeting the P. jirovecii mitochondrial large subunit rRNA gene and further at the DHPS locus. P. jirovecii DNA was detected in 50 (15.34%) specimens. A 370 bp DHPS locus fragment was successfully amplified in 21 samples from 19 PCP-positive patients, which was then purified, sequenced, and used for phylogenetic analysis. Based on the sequencing analysis, all (n = 21) P. jirovecii isolates showed DHPS genotype 1 (the wild type, with the nucleotide sequence ACA CGG CCT at codons 55, 56, and 57, respectively). In conclusion, infections caused by P. jirovecii mutants potentially resistant to sulfonamides are still rare events in Bulgaria. DHPS genotype 1 at codons 55 and 57 is the predominant P. jirovecii strain in the country.

Study on the Prevalence of Pneumocystis jirovecii as a Causative Agent of Lung Pathology in People with Different Immune Status

BACKGROUND

Pneumocystis pneumonia (PCP) commonly affects immunocompromised individuals, whereas in immunocompetent persons, it occurs relatively rarely, and in most cases, the Pneumocystis infection is detected as an asymptomatic colonization. The present study aimed to establish the prevalence of Pneumocystis jirovecii infection in human hosts with different immune status (immunocompromised and immunocompetent), using molecular diagnostic methods, and to compare their diagnostic value with that of classical staining methods.

METHODS

We used the collected-to-this-moment data from a prospective study on the prevalence of pneumocystosis among the Bulgarian population. Clinical specimens (including throat secretions, induced sputum, tracheal aspirates, and bronchoalveolar lavage) collected from 220 patients suspected of PCP (153 immunocompetent and 67 immunocompromised patients) were examined with microscopic staining methods and real-time PCR for detection of P. jirovecii. Results: DNA of the pathogen was detected in 38 (17%) specimens (32 immunocompromised patients and 6 immunocompetent subjects). From all 220 clinical samples examined by staining methods, only five (2%) P. jirovecii cysts were detected by the Gomori stain. All patients with PCP were treated with trimethoprim-sulfamethoxazole, but in ten of them (HIV-positive patients), the disease had a fatal outcome.

CONCLUSIONS

This study is the first in Bulgaria including the main available laboratory methods for diagnosis of human pneumocystosis. Regarding the etiological diagnosis of PCP, in our study the sensitivity of real-time PCR was higher compared to the staining methods. The choice of a method for sample collection and examination has an important role in the efficiency of the laboratory diagnostics.

Epidemiological and clinical characteristics of imported malaria in Bulgaria: A retrospective study of а 21-year period

BACKGROUND

Bulgaria, with a high endemicity for malaria in the past, was declared by the WHO as a malaria-free country in 1965. We intended to analyze the epidemiological and clinical implications of imported malaria cases in Bulgaria.

METHODS

This is a retrospective cross-sectional analysis of all recorded cases of imported malaria in Bulgaria over a 21-year period (2000-2020). Patients' clinical records and information gathered from the epidemiological survey of each recorded malaria case were reviewed.

RESULTS

A total of 232 cases of imported malaria were reported, 147 (63.4%) were Bulgarian citizens (BC) and 85 (36.6%) were foreign nationals (FN). Two thirds (66.4%) of cases were diagnosed from April to October. Most BCs had travelled for work (66.6%) to Africa (93.9%) and were infected with P. falciparum (83.3%), while most FNs were migrants (54.7%), exposed in Asia (63.5%) with P. vivax infection (62.4%). Clinical complications and a fatal outcome were noted in 14.7% (n = 34) and 3.5% (n = 8) of cases respectively. All complicated cases were in BNs with P. falciparum infection.

CONCLUSIONS

Bulgaria experiences a steady import of malaria. Efforts to improve diagnosis, management and prevention of malaria, as well as maintenance of a high degree of epidemiological vigilance are needed.

MIP-1a and MIP-1b in serum as potential markers of the severe course COVID-19

Purpose

Studying the pathogenesis of COVID-19 is necessary to developing of perspective predictors of severe course of disease and unfavorable prognosis. The macrophage activation syndrome observed in severe form of COVID-19 can potentially be used as a marker of poor prognosis, which makes it relevant to measure the levels of macrophage inflammatory proteins MIP-1a and MIP-1b.

Methods & Materials

Study included 80 patients (43 men and 37 women) aged 24 -90 years (mean = 58.3 years) with laboratory confirmed COVID-19 admitted Infectious Diseases Hospital in Moscow during April - August 2020. Patients were divided into 2 groups: group 1 included patients with a moderate form (N = 30), group 2 (N = 50) included patients with a severe form of COVID-19. Serum levels of MIP-1a and MIP-1b were assessed by ELISA.

Results

An increase of the MIP-1a level was observed in 3 patients in group 1 (10%) and in 42 patients in group 2 (84%). At the same time, the average concentration of MIP-1a was 3.71 pg/ml and 156.79 pg/ml in groups 1 and 2, respectively (p < 0.01).

MIP-1b level above baseline was detected in 11 patients in group 1 (36.7%) and in 48 patients in group 2 (96%). The mean MIP-1b concentrations were 7.53 pg/ml and 152.62 pg/ml in groups 1 and 2, respectively. Similarly with MIP-1a, the difference in mean MIP-1b concentrations between the two groups was statistically significant (p < 0.01).

A statistically significant correlation between the concentrations of MIP-1a and MIP-1b was observed for whole study population, the Pearson's correlation coefficient (r) is 0.756 (p < 0.01). At the same time, there were no statistically significant differences related to gender and age. Taken together, these data suggest the potential of serum concentrations of MIP-1a and MIP-1b as markers of the disease severity.

Conclusion

COVID-19 is accompanied by an increase in the level of macrophage inflammatory proteins. The severe disease in most cases was associated with significant increase in the concentrations of MIP-1a and MIP-1b in the blood serum, which makes it possible to consider these proteins as potential markers of the severe COVID-19.

Human Parasitic Diseases in Bulgaria in Between 2013-2014

BACKGROUND

In Bulgaria, more than 20 autochthonous human parasitic infections have been described and some of them are widespread. Over 50 imported protozoan and helminthic infections represent diagnostic and therapeutic challenges and pose epidemiological risks due to the possibility of local transmission.

AIMS

To establish the distribution of autochthonous and imported parasitic diseases among the population of the country over a 2-year period (2013-2014) and to evaluate their significance in the public health system.

STUDY DESIGN

Cross sectional study.

METHODS

We used the annual reports by regional health inspectorates and data from the National Reference Laboratory at the National Centre of Infectious and Parasitic Diseases on all individuals infected with parasitic diseases in the country. Prevalence was calculated for parasitic diseases with few or absent clinical manifestations (oligosymptomatic or asymptomatic infections). Incidence per 100.000 was calculated for diseases with an overt clinical picture or those that required hospitalisation and specialised medical interventions (e.g. surgery).

RESULTS

During the research period, parasitological studies were conducted on 1441.244 persons, and parasitic infections were diagnosed in 22.039 individuals. Distribution of various parasitic pathogens among the population displayed statistically significant differences in prevalence for some intestinal parasites (enterobiasis 0.81%, giardiasis 0.34% and blastocystosis 0.22%). For certain zoonotic diseases such as cystic echinococcosis (average incidence of 3.99 per 100.000) and trichinellosis (average incidence of 0.8 per 100.000), the incidence exceeds several times the annual incidence recorded in the European Union.

CONCLUSION

Parasitic diseases still pose a substantial problem with social and medical impacts on the residents of our country. Improved efficiency regarding autochthonous and imported parasitic diseases is essential in providing the public health system the tools it needs to combat these diseases. Attention should be focused on the various imported vector-borne parasitic diseases (e.g. malaria and cutaneous leishmaniasis) for which the country is potentially endemic.

Hybrid dwarfness in crosses between wheat (Triticum aestivum L.) and rye (Secale cereale L.): a new look at an old phenomenon

The existence of hybrid dwarfs from intraspecific crosses in wheat (Triticum aestivum) was described 100 years ago, and the genetics underlying hybrid dwarfness are well understood. In this study, we report a dwarf phenotype in interspecific hybrids between wheat and rye (Secale cereale). We identified two rye lines that produce hybrid dwarfs with wheat and have none of the hitherto known hybrid dwarfing genes. Genetic analyses revealed that both rye lines carry a single allelic gene responsible for the dwarf phenotype. This gene was designated Hdw-R1 (Hybrid dwarf-R1). Application of gibberellic acid (GA3 ) to both intraspecific (wheat-wheat) and interspecific (wheat-rye) hybrids showed that hybrid dwarfness cannot be overcome by treatment with this phytohormone. Histological analysis of shoot apices showed that wheat-rye hybrids with the dwarf phenotype at 21 and 45 days after germination failed to develop further. Shoot apices of dwarf plants did not elongate, did not form new primordia and had a dome-shaped appearance in the seed. The possible relationship between hybrid dwarfness and the genes responsible for the transition from vegetative to generative growth stage is discussed.

Occurrence of Giardia and Cryptosporidium in water supplies of Russia and Bulgaria

The aim of the present study was to investigate water supplies in southern Russia and Bulgaria, in order to estimate the occurrence of Giardia and Cryptosporidium in drinking water resources from these countries. A total of 166 water samples of different origin (surface, tap, bottled, well, spring and waste water) were collected from Rostov (southern Russia), Sofia and Varna (Bulgaria) Greater Areas and screened for the detection of Giardia cysts and Cryptosporidium oocysts. The method incorporated concentration of water samples by filtration and flocculation, sucrose purification, (oo)cyst detection/identification by immunofluorescence test and differential interference contrast. Sixteen out of 166 samples (9.6%) were positive for Giardia and 30 (18.1%) positive for Cryptosporidium. Both Giardia and Cryptosporidium were detected in tap, river, well and waste waters. Giardia cysts were additionally detected in bottled water. Particularly some river, waste and well water samples were highly contaminated with (oo)cysts. This study has shown that drinking water supplies in Russia and Bulgaria are subject to contamination with Giardia and Cryptosporidium, with potential hazards for the public health.

Characterisation of Trichinella isolates from Bulgaria by molecular typing and cross-breeding

Trichinella spp. larvae were collected from domestic and wild-life animals in association with 15 human trichinellosis outbreaks registered between 1999-2002 in Bulgaria. Furthermore, Trichinella spp. isolates were obtained from 62 naturally infected wild animals and of a rat. All isolates were subjected to speciation by both multiplex PCR and cross-breeding experiments. Epidemiological and clinical data were collected and analysed using standard protocols for epidemiological surveillance and control of outbreaks. Only two species were identified-Trichinella britovi and Trichinella spiralis. Results obtained by molecular typing fully matched those of cross-breeding. More specifically, parasite isolates obtained upon 15 epidemic outbreaks revealed the predominance of T. britovi (n = 10) when compared to T. spiralis (n = 5). With regard to host origin, the predominant species detected among wild boar was T. britovi (n = 4), and T. spiralis was identified in one wild boar sample only. Among the isolates obtained from domestic pig products, T. britovi was found in five cases and T. spiralis in four cases, respectively. In the naturally infected wild animals not related to epidemics, only T. britovi was demonstrated. The present results provide a strong indication that both T. britovi and T. spiralis operate within domestic and sylvatic cycles in Bulgaria. Geographically, the distribution of T. britovi appears to include Central, Southern, Eastern and Western parts of the country, and wildlife animals from the Mid Balkan Mountains and Mid Sredna Gora Mountains, T. spiralis was found in Western and Southwestern Bulgaria, only.

The identification of free-living environmental isolates of amoebae from Bulgaria

A survey was carried out in Bulgaria to determine the presence of free-living amoebae (FLA) from environmental sources. In 171 (61.1%) of 280 samples, isolates of Acanthamoeba with group II or III morphology, as well as Hartmannella spp. were recovered. Five isolates named "6" (artificial lake), Ep (lake), G2 (soil), R4* (river) and PK (spring water)--all exhibiting a highly efficient proliferation in axenic cultures--were subsequently cloned and subjected to molecular analyses for identification and genotyping In accordance with morphological findings, PCR-based analyses identified four isolates (6, Ep, G2, R4*) belonging to the genus Acanthamoeba. Confirmation of these findings was obtained by phylogenetic analysis using partial sequencing of the 18S rDNA (ASA.S1) Acanthamoeba-gene. Comparison of these sequences with corresponding regions from other Acanthamoeba strains available from GenBank sorted all four isolates into the sequence type group T4 that contains most of the pathogenic Acanthamoeba strains already identified. The fifth isolate (PK) exhibited morphological characteristics matching those of Hartmannella, and scored negative in the Naegleria fowleri and Acanthamoeba PCRs.

The trehalose myth revisited: introduction to a symposium on stabilization of cells in the dry state

This essay is an introduction to a series of papers arising from a symposium on stabilization of cells in the dry state. Nearly all of these investigations have utilized the sugar trehalose as a stabilizing molecule. Over the past two decades a myth has grown up about special properties of trehalose for stabilization of biomaterials. We review many of such uses here and show that under ideal conditions for drying and storage trehalose has few, if any, special properties. However, under suboptimal conditions trehalose has some distinct advantages and thus may remain the preferred excipient. We review the available mechanisms for introducing trehalose into the cytoplasm of living cells as an introduction to the papers that follow.

Comparison of the solution conformation and dynamics of antifreeze glycoproteins from Antarctic fish

The (1)H- and (13)C-NMR spectra of antifreeze glycoprotein fractions 1-5 from Antarctic cod have been assigned, and the dynamics have been measured using (13)C relaxation at two temperatures. The chemical shifts and absence of non-sequential (1)H-(1)H NOEs are inconsistent with a folded, compact structure. (13)C relaxation measurements show that the protein has no significant long-range order, and that the local correlation times are adequately described by a random coil model. Hydroxyl protons of the sugar residues were observed at low temperature, and the presence of exchange-mediated ROEs to the sugar indicate extensive hydration. The conformational properties of AFGP1-5 are compared with those of the previously examined 14-mer analog AFGP8, which contains proline residues in place of some alanine residues (Lane, A. N., L. M. Hays, R. E. Feeney, L. M. Crowe, and J. H. Crowe. 1998. Protein Sci. 7:1555-1563). The infrared (IR) spectra of AFGP8 and AFGP1-5 in the amide I region are quite different. The presence of a wide distribution of backbone torsion angles in AFGP1-5 leads to a rich spectrum of frequencies in the IR spectrum, as interconversion among conformational states is slow on the IR frequency time scale. However, these transitions are fast on the NMR chemical shift time scales. The restricted motions for AFGP8 may imply a narrower distribution of possible o, psi angles, as is observed in the IR spectrum. This has significance for attempts to quantify secondary structures of proteins by IR in the presence of extensive loops.

Are lipid phase transitions responsible for chilling damage in human platelets?

In previous studies we have proposed that the well-known chilling-induced activation of human blood platelets can be ascribed at least in part to a thermotropic phase transition in membrane lipids. The evidence that this is the case is reviewed and amplified in this review, followed by an examination of the available physical data concerning phase transitions in lipid mixtures that mimic the mixture found in platelet membranes. Assuming complete mixing at all temperatures and equal contributions of the members of the mixture to the phase transition, the lipid mixture found in platelets should give values for Tm ranging from about 1 degrees C to about 16 degrees C, depending on the isomers present in the mixture. (The former value is not in agreement with the observed Tm, but the latter is in excellent agreement.) However, examination of the phase diagram for a binary pair of lipids found in platelet membranes shows that ideal mixing almost certainly does not occur; instead of a linear phase diagram, a convex one was obtained. This shape for the phase diagram, which would displace Tm to an unexpectedly elevated temperature, is in agreement with previously published phase diagrams for mixtures of this type. The prediction, based on thermodynamic properties of lipids found in the platelets, is that Tm will be displaced upward in more complex mixtures of the composition found in platelets, a prediction that requires experimental testing.

Genetic Enhancement of the Ability to Tolerate Photoinhibition by Introduction of Unsaturated Bonds into Membrane Glycerolipids

Strong light leads to damage to photosynthetic machinery, particularly at low temperatures, and the main site of the damage is the D1 protein of the photosystem II (PSII) complex. Here we describe that transformation of Synechococcus sp. PCC 7942 with the desA gene for a [delta]12 desaturase increased unsaturation of membrane lipids and enhanced tolerance to strong light. To our knowledge, this is the first report of the successful genetic enhancement of tolerance to strong light. Analysis of the light-induced inactivation and of the subsequent recovery of the activity of the PSII complex revealed that the recovery process was markedly accelerated by the genetic transformation. Labeling experiments with [35S]L-methionine also revealed that the synthesis of the D1 protein de novo at low temperature, which was a prerequisite for the restoration of the PSII complex, was much faster in the transformed cells than in the wild-type cells. These findings demonstrate that the ability of membrane lipids to desaturate fatty acids is important for the photosynthetic organisms to tolerate strong light, by accelerating the synthesis of the D1 protein de novo.

Dependence of trehalose protective action on the initial phase state of dipalmitoylphosphatidylcholine bilayers

Dipalmitoylphosphatidylcholine (DPPC) bilayers hydrated in the presence of trehalose were equilibrated at various temperatures (4, 20, and 60 degrees C) corresponding to the crystalline Lc, gel L beta', and liquid-crystalline L alpha phases, respectively, and then desiccated at these temperatures or freeze-dried at -80 degrees C to ca. DPPC dihydrate. The thermotropic behavior of the resulting DPPC/trehalose mixtures was investigated by differential scanning calorimetry and found to be dependent not only on the trehalose concentration but also on the phase state of the hydrated bilayers prior to their drying. Trehalose was most effective when the desiccation was carried out from the L alpha phase at 60 degrees C. In this case, one trehalose molecule per two DPPC molecules was sufficient to depress the melting temperature from values typical of DPPC dihydrate to 45 degrees C. Trehalose's influence decreased when dried from the L beta' phase and was significantly less pronounced when dried from the Lc phase. These data show that trehalose's protective influence depends on the initial phase state of the lipid bilayer and reaches its maximum in the liquid-crystalline state. The possible role of this effect in anhydrobiosis is pointed out.