Prevalence of SARS-CoV-2 in domestic cats (Felis catus) during COVID-19 pandemic in Latvia

BACKGROUND

The causative agent of the COVID-19 pandemic, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is of zoonotic origin and has shown reverse zoonotic transmissibility.

OBJECTIVES

The aim of this cross-sectional study was to investigate the serological and molecular prevalence of SARS-CoV-2 infection in the domestic cat (Felis catus) population from Latvia in natural conditions and subsequently perform viral genome analysis.

METHODS

Oropharyngeal and rectal swabs and blood samples were collected from 273 domestic cats during the second wave of COVID-19 infection in Latvia. Molecular prevalence was determined by using reverse transcriptase-polymerase chain reaction (RT-PCR). Serum samples were analysed via double antigen enzyme-linked immunosorbent assay targeting the antibody against the nucleocapsid protein of SARS-CoV-2. Positive swab samples were analysed using whole viral genome sequencing and subsequent phylogenetic analysis of the whole genome sequencing data of the samples was performed.

RESULTS

The overall SARS-CoV-2 RT-PCR positivity and seroprevalence was 1.1% (3/273) and 2.6% (7/273), respectively. The SARS-CoV-2 genome sequences from three RT-PCR positive cats were assigned to the three common lineages (PANGOLIN lineage S.1.; B.1.177.60. and B.1.1.7.) circulating in Latvia during the particular period of time.

CONCLUSIONS

These findings indicate that feline infection with SARS-CoV-2 occurred during the second wave of the COVID-19 pandemic in Latvia, yet the overall prevalence was low. In addition, it seems like no special 'cat' pre-adaptations were necessary for successful infection of cats by the common lineages of SARS-CoV-2.

Genetic characterization of the Latvian local goat breed and genetic traits associated with somatic cell count

The Latvian local goat (LVK) breed represents the only native domestic goat breed in Latvia, but its limited population places it within the endangered category. However, the LVK breed has not yet undergone a comprehensive genetic characterization. Therefore, we completed whole genome sequencing to reveal the genetic foundation of the LVK breed while identifying genetic traits linked to the somatic cell count (SCC) levels. The study included 40 genomes of LVK goats sequenced to acquire at least 35x or 10x coverage. A Principal component analysis, a genetic distance tree, and an admixture analysis showed LVK's similarity to some European breeds, such as Finnish Landrace, Alpine, and Saanen, which aligns with the breed's history. An analysis of genome-wide heterozygosity, nucleotide diversity, and LD analysis indicated that the LVK population exhibits substantial levels of genetic diversity. LVK genome was dominated by short runs of homozygosity (ROHs, ≤ 500 kb) with a median length of 25 kb. With FROH 2.49%, average inbreeding levels were low; however, FROH ranged broadly from 0.13 to 12.2%. With the exception of one pure-blood breeding buck exhibiting FROH of 9.3% and FSNP of 8.5%, animals with at least 66% LVK ancestry showed moderate or no inbreeding. Overall, this study demonstrated that the LVK goats can be differentiated from imported breeds, although the population has a complex genetic structure. We were able to identify potential genetic traits associated with SCC levels, although the kinship of the animals and the heterogenic substructure of the population might have largely influenced the association analysis. We identified 26 genetic variants associated with SCC levels, which included the potentially relevant SNP rs662053371 in the OSBPL8 gene, indicating a potential signal linked to lipid metabolism in goats. To conclude, these findings present valuable insight into the genetic structure of the LVK breed for the conservation of local genetic resources.

Characterization of a putative orexin receptor in Ciona intestinalis sheds light on the evolution of the orexin/hypocretin system in chordates

Tunicates are evolutionary model organisms bridging the gap between vertebrates and invertebrates. A genomic sequence in Ciona intestinalis (CiOX) shows high similarity to vertebrate orexin receptors and protostome allatotropin receptors (ATR). Here, molecular phylogeny suggested that CiOX is divergent from ATRs and human orexin receptors (hOX1/2). However, CiOX appears closer to hOX1/2 than to ATR both in terms of sequence percent identity and in its modelled binding cavity, as suggested by molecular modelling. CiOX was heterologously expressed in a recombinant HEK293 cell system. Human orexins weakly but concentration-dependently activated its Gq signalling (Ca2+ elevation), and the responses were inhibited by the non-selective orexin receptor antagonists TCS 1102 and almorexant, but only weakly by the OX1-selective antagonist SB-334867. Furthermore, the 5-/6-carboxytetramethylrhodamine (TAMRA)-labelled human orexin-A was able to bind to CiOX. Database mining was used to predict a potential endogenous C. intestinalis orexin peptide (Ci-orexin-A). Ci-orexin-A was able to displace TAMRA-orexin-A, but not to induce any calcium response at the CiOX. Consequently, we suggested that the orexin signalling system is conserved in Ciona intestinalis, although the relevant peptide-receptor interaction was not fully elucidated.

Impact of Anthropogenic Activities on Microbial Community Structure in Riverbed Sediments of East Kazakhstan

Heavy metal (HMe) pollution in regions with mining and metallurgy activities is known to be a serious environmental problem worldwide. Hydrological processes contribute to the dissemination of HMes (drainage, precipitation, flow rate). The aim of the present study is to investigate the microbial community structure in ten river sediments sampled in different regions of East Kazakhstan, which are contaminated with HMes. The overall degree of sediment contamination with HMes (Cr, Cu, Zn, Pb, and Cd) was assessed using the pollution index Zc, which ranged from 0.43 to 21.6, with the highest in Ridder City (Zc = 21.6) and Ust-Kamenogorsk City, 0.8 km below the dam of the hydroelectric power station (Zc = 19.6). The tested samples considerably differed in organic matter, total carbon, nitrogen, and phosphorus content, as well as in the abundance of HMe-related functional gene families and antibiotic resistance genes. Metagenomic analysis of benthic microorganisms showed the prevalence of Proteobacteria (88.84-97.61%) and Actinobacteria (1.21-5.98%) at the phylum level in all samples. At the class level, Actinobacteria (21.68-57.48%), Betaproteobacteria (19.38-41.17%), and Alphaproteobacteria (10.0-39.78%) were the most common among the classified reads. To the best of our knowledge, this is the first study on the metagenomic characteristics of benthic microbial communities exposed to chronic HMe pressure in different regions of East Kazakhstan.

Evaluation of pathogenicity of Botrytis species isolated from different legumes

Fungi of genus Botrytis are important pathogens of legumes, causing gray mold and chocolate spot diseases. The use of molecular methods to identify pathogens has resulted in the discovery of several new Botrytis species and new associations of pathogens with diseases. Thus, chocolate spot of faba bean is now associated with at least four species: B. fabae, B. cinerea, B. pseudocinerea and B. fabiopsis. Species of Botrytis differ in host plant, pathogenicity, fungicide resistance and other relevant properties that affect disease control. The aim of this study was to identify the species of Botrytis isolated from different legume crops and to evaluate their in vitro pathogenicity. Between 2014 and 2019, 278 isolates of Botrytis were obtained from infected legumes in Latvia. A phylogenetic analysis was carried out by sequencing three nuclear genes, RPB2, HSP60, and G3PDH, considered to be diagnostic for species in this genus. A set of 21 representative isolates was selected for pathogenicity tests on detached leaves of faba bean, field pea, lupin and soybean using 5-mm mycelium-agar plugs. The diameter of the formed lesions under the inoculated plug was measured crosswise each day. The datasets were subjected to analysis of variance with the split-plot design of the experiment and repeated-measures model. Six species were identified: B. cinerea, B. fabae, B. pseudocinerea, B. fabiopsis, B. euroamericana and B. medusae. In addition to the expected combinations of host and pathogen, naturally occurring infections of B. fabiopsis were found on chickpea, B. euroamericana on faba bean and B. medusae in lupin seeds. Species and isolate had significant effects on pathogenicity on all crops tested. Several isolates were pathogenic on two or more host species: two of B. pseudocinerea, two of B. cinerea, two of B. fabiopsis and the one of B. medusae. One isolate of B. pseudocinerea and two of B. fabiopsis caused primary lesions on all five host species. The results show that these Botrytis species have a broad host range that should be borne in mind when planning crop sequences and rotations.

Spatial variation of the gut microbiome in response to long-term metformin treatment in high-fat diet-induced type 2 diabetes mouse model of both sexes

Antidiabetic drug metformin alters the gut microbiome composition in the context of type 2 diabetes and other diseases; however, its effects have been mainly studied using fecal samples, which offer limited information about the intestinal site-specific effects of this drug. Our study aimed to characterize the spatial variation of the gut microbiome in response to metformin treatment by using a high-fat diet-induced type 2 diabetes mouse model of both sexes. Four intestinal parts, each at the luminal and mucosal layer level, were analyzed in this study by performing 16S rRNA sequencing covering six variable regions (V1-V6) of the gene and thus allowing to obtain in-depth information about the microbiome composition. We identified significant differences in gut microbiome diversity in each of the intestinal parts regarding the alpha and beta diversities. Metformin treatment altered the abundance of different genera in all studied intestinal sites, with the most pronounced effect in the small intestine, where Lactococcus increased remarkably. The abundance of Lactobacillus was substantially lower in male mice compared to female mice in all locations, in addition to an enrichment of opportunistic pathogens. Diet type and intestinal layer had significant effects on microbiome composition at each of the sites studied. We observed a different effect of metformin treatment on the analyzed subsets, indicating the multiple dimensions of metformin's effect on the gut microbiome.

The Diversity of Fungi Involved in Damage to Japanese Quince

In recent years, Japanese quince (Chaenomeles japonica) plantations in Latvia have increased. Interest in breeding Japanese quince is also known in other European countries and Russia. The occurrence and harmfulness of fungal diseases have become increasingly significant. However, there is a lack of overall information in the literature about the diversity of fungi afflicting C. japonica. In our study, we aimed to determine the diversity of fungi associated with C. japonica in Latvia, with the possibility of identifying the fungi that are most characteristically associated with certain parts of the plant. Our research was conducted from 2017 to 2019 in eight Japanese quince plantations in Latvia. Samples of plant parts with disease symptoms were collected. Pure cultures of fungi were obtained and identified using ITS region sequencing. We determined the relative density of identified genera of fungi, which were grouped using hierarchical cluster analysis depending on the plant part from which they were found. Various disease-like symptoms were observed and described. A total of 538 isolates of fungi were obtained that belong to 36 genera and represent different ecological niches. Fusarium, Alternaria, Botrytis, and Sarocladium were the genera most frequently found during our study. The number of identified cases of fungal genera differed depending on the part of the plant from which the fungi were obtained. However, it is not possible to relate a specific genus of fungus to only one certain part of a plant. Further research is needed to clarify the pathogenicity of detected fungi and the composition of species in the detected genera of fungi.

Stimulation of sewage sludge treatment by carbon sources and bioaugmentation with a sludge-derived microbial consortium

Recently, sewage sludge (SS) disposal has become one of the greatest global challenges. In this study, we aimed to evaluate the effect of faba bean straw (Straw-B), wheat straw (Straw-W), and wood-chip pellets (WCP) amended to SS, as well as bioaugmentation (BA), on the physicochemical characteristics and structure of the microbial community of the treated SS. Sixteen days of incubation of SS-containing mixtures revealed the highest efficiency of Straw-W(BA) in terms of SS stabilisation, i.e., the highest and most stable respiration intensity, the lowest ammonia emission, and the highest stimulation effect on the cress seedling growth. Shotgun sequencing data analysis showed that Proteobacteria dominated in the raw SS with 60.17% reads, which consisted of 16.40%, 29.18%, and 12.33% of Alphaproteobacteria, Betaproteobacteria, and Gammaproteobacteria, respectively. All treated samples were characterised by an increased abundance of Firmicutes (32.70-53.84%). A remarkable increase in virus abundance (0.34% reads) was detected in the treated SS, which was incubated without C amendment and bioaugmentation. The addition of C sources to the SS changed some physicochemical characteristics of the mixture. All of these findings provide novel insights toward a mechanistic understanding of the fate of the human sewage microbiome in wastewater and other environments.

Selective enrichment of heterotrophic nitrifiers Alcaligenaceae and Alcanivorax spp. from industrial wastewaters

Removal of nitrogen from wastewaters (WW) represents a global problem. The low nitrification rate during WW treatment is often caused by ecotoxicity. This problem is attributed mostly to the industrial WW. Our study was focused on the testing of industrial WW and activated sludge (AS) with the aim to reveal the abundance of nitrifiers and increase their biomass, thus, providing the additional step, i.e., bioaugmentation, within the technological process of WW treatment. Plating of AS on the selective solidified media designated for the 1st and 2nd nitrification stages, resulted in the shift in bacterial community structure with dominated Alcaligenaceae and Alcanivorax for the 1st stage, and Alcanivorax-for the 2nd stage of nitrification, respectively. Incubation of AS in the presence of real WW and selective nitrification broth resulted in a considerable increase (one or two magnitudes in the presence of the 1st and 2nd stage nitrification broth, respectively) of culturable nitrifiers after 5 days incubation under aerated conditions. The obtained data provide with evidence about a possibility to strengthen the role of heterotrophic nitrifiers in the treatment of industrial WW, where toxicity obstacles inhibited nitrification under conventional conditions.

Control of Acinetobacter baumannii outbreak in the neonatal intensive care unit in Latvia: whole-genome sequencing powered investigation and closure of the ward

Background

Acinetobacter baumannii is an emerging pathogen capable of causing hospital-acquired infections (HAIs). It has the ability to survive on environmental surfaces for months, making transmission difficult to control. Our report describes the investigation and restriction of an outbreak of A.baumannii in the Neonatal Intensive Care Unit (NICU) using whole-genome sequencing (WGS) and multi-modal infection control measures.

Methods

A prospective surveillance of HAIs was initiated in the NICU at the Pauls Stradins Clinical University Hospital (PSCUH) in Latvia on 1/9/2012 and identified an outbreak of A.baumannii. Case definitions for A.baumannii bloodstream infection (BSI) and colonization were implemented; surveillance cultures were obtained from all admitted patients to monitor the rate of colonization; an infection prevention and control team was formed and infection control interventions implemented. Environmental sampling of the NICU and Labour ward was performed. We employed WGS to differentiate phenotypically identical multidrug-resistant A.baumannii (MDRAB) strains from simultaneous intrahospital outbreaks in the adult Intensive Care Unit and NICU.

Results

Between 1/9/2012 and 31/12/2017 the surveillance included 2157 neonates. A total of 17 neonates had A.baumannii BSI, with the highest rate of 30.0 cases per 1000 bed-days in November 2012. Rectal screening samples were positive for A.baumannii-complex in 182 neonates reaching 119.6 per 1000 bed-days in July 2015. All 298 environmental cultures were negative. Two phenotypically identical MDRAB isolates from the simultaneous intrahospital outbreaks were differentiated using WGS, ruling out an inter-ward transmission. Adherence to stringent infection control measures decreased BSI cases but colonization remained persistent. With several relapses, the outbreak was ongoing for four years. No new A.baumannii BSI cases were registered after total environmental decontamination in the NICU in July 2015. Colonization reappeared and persisted until in November 2016 when the ward was temporarily closed, relocated and renovated. No A.baumannii cases were registered after the renovation.

Conclusion

The HAI surveillance system successfully detected and facilitated the control of the A.baumannii outbreak. Whole-genome sequencing was found to be a useful method for differentiation of phenotypically identical A.baumannii strains from the intrahospital outbreak. Only multi-modal infection control program, including closure, temporary relocation, and renovation of the ward, restricted the outbreak.

Microbiome symbionts and diet diversity incur costs on the immune system of insect larvae

Communities of symbiotic microorganisms that colonize the gastrointestinal tract play an important role in food digestion and protection against opportunistic microbes. Diet diversity increases the number of symbionts in the intestines, a benefit that is considered to impose no cost for the host organism. However, less is known about the possible immunological investments that hosts have to make in order to control the infections caused by symbiont populations that increase because of diet diversity. Using taxonomical composition analysis of the 16S rRNA V3 region, we show that enterococci are the dominating group of bacteria in the midgut of the larvae of the greater wax moth (Galleria mellonella). We found that the number of colony-forming units of enterococci and expressions of certain immunity-related antimicrobial peptide (AMP) genes such as Gallerimycin, Gloverin, 6-tox, Cecropin-D and Galiomicin increased in response to a more diverse diet, which in turn decreased the encapsulation response of the larvae. Treatment with antibiotics significantly lowered the expression of all AMP genes. Diet and antibiotic treatment interaction did not affect the expression of Gloverin and Galiomicin AMP genes, but significantly influenced the expression of Gallerimycin, 6-tox and Cecropin-D Taken together, our results suggest that diet diversity influences microbiome diversity and AMP gene expression, ultimately affecting an organism's capacity to mount an immune response. Elevated basal levels of immunity-related genes (Gloverin and Galiomicin) might act as a prophylactic against opportunistic infections and as a mechanism that controls the gut symbionts. This would indicate that a diverse diet imposes higher immunity costs on organisms.

Association between CETP, MLXIPL, and TOMM40 polymorphisms and serum lipid levels in a Latvian population

Background

Abnormal lipid levels are considered one of the most significant risk factors for atherosclerosis and coronary artery disease, two of the main causes of death worldwide. Apart from monogenic cases of hypercholesterolemia, most of the common dyslipidemias are caused by a number of low-impact polymorphisms. It has recently been reported that frequent polymorphisms at a large number of loci are significantly associated with one or more blood lipid parameters in many populations. Identifying these associations in different populations and estimating the possible interactions between genetic models are necessary to explain the underlying genetic architecture of the associated loci and their ultimate impact on lipid-associated traits.

Methods

We estimated the association between 144 common single-nucleotide polymorphisms (SNPs) from published genome-wide association studies and the levels of total cholesterol, low- and high-density lipoprotein–cholesterol, and triglycerides in 1273 individuals from the Genome Database of the Latvian Population. We analyzed a panel of 144 common SNPs with Illumina GoldenGate Genotyping Assays on the Illumina BeadXpress System.

Results

Ten SNPs at the CETP locus and two at the MLXIPL locus were associated with reduced high-density lipoprotein–cholesterol levels; one SNP at the TOMM40 locus was associated with increased low-density lipoprotein–cholesterol; and four SNPs at the MLXIPL locus were associated with increased log triglyceride levels. There was also a significant correlation between the number of risk alleles and all the lipid parameters, suggesting that the coexistence of many low-impact SNPs has a greater effect on the dyslipidemia phenotype than the individual effects of found SNPs.

Conclusion

We conclude that the CETP, MLXIPL, and TOMM40 loci are the strongest genetic factors underlying the variability in lipid traits in our population.

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Genotyping of 144 common SNPs associated with blood lipids in Latvian population

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16 common SNPs are associated with blood lipid levels in Latvian population.

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The number of risk alleles influences the level of blood lipids.

Stronger association of common variants in TCF7L2 gene with nonobese type 2 diabetes in the Latvian population

Polymorphisms in the gene coding for transcription factor 7 like 2 (TCF7L2) are recognized as the strongest common genetic risk factors for type 2 diabetes (T2D) across multiple ethnicities. This study was conducted to evaluate an association between TCF7L2 variants and diabetes susceptibility in the population of Latvia. We genotyped 4 single nucleotide polymorphisms (SNP) rs7901695, rs7903146, rs11196205 and rs12255372 in 1 093 controls and 1 043 diabetic subjects. Association with T2D was found for 3 SNPs rs7901695, rs7903146 and rs12255372 in the whole sample (under an additive genetic model, the adjusted odds ratios (OR) were 1.26, 95% CI [1.08-1.48], P=0.003; OR=1.32, 95% CI [1.12-1.55], P=0.001 and OR=1.35, 95% CI [1.15-1.60], P=0.0004 respectively). In addition observed effects on T2D susceptibility for analysed SNPs were higher among subjects with BMI under 30 kg/m². The impact of TCF7L2 variation on T2D risk in Latvian population is compatible with that demonstrated by a range of studies conducted in various ethnic groups.