Rapid DNA extraction from dried blood spots on filter paper: potential applications in biobanking

Potential for and challenges of menstrual blood as a non-invasive diagnostic specimen: current status and future directions

Menstrual blood, which is often discarded as a waste product, has emerged as a valuable source of health information. The components of menstrual blood, such as endometrial cells, immune cells, proteins, and microbial signatures, provide insights into health. Studies have shown encouraging results for using menstrual blood to diagnose a variety of conditions, including hormonal imbalances, cervical cancer, endometriosis, chlamydia, diabetes, and other endocrine disorders. This review examines the potential of menstrual blood as a non-invasive diagnostic specimen, exploring its composition, promising applications, and recent advances. This review also discusses challenges to utilizing menstrual blood testing, including ethical considerations, the lack of standardized collection protocols, extensive validation studies, and the societal stigma around menstruation. Overcoming these challenges will open new avenues for personalized medicine and revolutionize healthcare for individuals who menstruate.

Caught in a trap: DNA contamination in tsetse xenomonitoring can lead to over-estimates of Trypanosoma brucei infection

BACKGROUND

Tsetse flies (Glossina sp.) are vectors of Trypanosoma brucei subspecies that cause human African trypanosomiasis (HAT). Capturing and screening tsetse is critical for HAT surveillance. Classically, tsetse have been microscopically analysed to identify trypanosomes, but this is increasingly replaced with molecular xenomonitoring. Nonetheless, sensitive T. brucei-detection assays, such as TBR-PCR, are vulnerable to DNA cross-contamination. This may occur at capture, when often multiple live tsetse are retained temporarily in the cage of a trap. This study set out to determine whether infected tsetse can contaminate naïve tsetse with T. brucei DNA via faeces when co-housed.

METHODOLOGY/PRINCIPLE FINDINGS

Insectary-reared teneral G. morsitans morsitans were fed an infectious T. b. brucei-spiked bloodmeal. At 19 days post-infection, infected and naïve tsetse were caged together in the following ratios: (T1) 9:3, (T2) 6:6 (T3) 1:11 and a control (C0) 0:12 in triplicate. Following 24-hour incubation, DNA was extracted from each fly and screened for parasite DNA presence using PCR and qPCR. All insectary-reared infected flies were positive for T. brucei DNA using TBR-qPCR. However, naïve tsetse also tested positive. Even at a ratio of 1 infected to 11 naïve flies, 91% of naïve tsetse gave positive TBR-qPCR results. Furthermore, the quantity of T. brucei DNA detected in naïve tsetse was significantly correlated with cage infection ratio. With evidence of cross-contamination, field-caught tsetse from Tanzania were then assessed using the same screening protocol. End-point TBR-PCR predicted a sample population prevalence of 24.8%. Using qPCR and Cq cut-offs optimised on insectary-reared flies, we estimated that prevalence was 0.5% (95% confidence interval [0.36, 0.73]).

CONCLUSIONS/SIGNIFICANCE

Our results show that infected tsetse can contaminate naïve flies with T. brucei DNA when co-caged, and that the level of contamination can be extensive. Whilst simple PCR may overestimate infection prevalence, quantitative PCR offers a means of eliminating false positives.

Optimization of Total DNA Extraction from Dried Blood Samples

While dried blood spots are a convenient source of genetic material, they are usually associated with a lower DNA yield than from a native sample. The study evaluated the DNA yield from dried blood samples prepared on glass fibre and cellulose membranes and investigated the reasons for the yield reduction. The extraction of total DNA from membrane-dried blood samples was optimized by spin-column extraction method. It was shown that preliminary short-term (20 min) solubilization of a dried matrix in an aqueous medium, followed by standard extraction protocols for the mixture of the eluate with membranes, provides the highest DNA yield. The yield of DNA from a glass fibre membrane was 40-50% lower compared to a native sample, but on average, two times higher than from a conventional cellulose membrane (filter paper). The reduction of DNA yield when using a dried sample was found to be due to partial retention of nucleic acids by the membrane material during the lysis stage.

Detection of Duffy blood group genotypes and submicroscopic Plasmodium infections using molecular diagnostic assays in febrile malaria patients

BACKGROUND

Malaria remains a severe parasitic disease, posing a significant threat to public health and hindering economic development in sub-Saharan Africa. Ethiopia, a malaria endemic country, is facing a resurgence of the disease with a steadily rising incidence. Conventional diagnostic methods, such as microscopy, have become less effective due to low parasite density, particularly among Duffy-negative human populations in Africa. To develop comprehensive control strategies, it is crucial to generate data on the distribution and clinical occurrence of Plasmodium vivax and Plasmodium falciparum infections in regions where the disease is prevalent. This study assessed Plasmodium infections and Duffy antigen genotypes in febrile patients in Ethiopia.

METHODS

Three hundred febrile patients visiting four health facilities in Jimma town of southwestern Ethiopia were randomly selected during the malaria transmission season (Apr-Oct). Sociodemographic information was collected, and microscopic examination was performed for all study participants. Plasmodium species and parasitaemia as well as the Duffy genotype were assessed by quantitative polymerase chain reaction (qPCR) for all samples. Data were analysed using Fisher's exact test and kappa statistics.

RESULTS

The Plasmodium infection rate by qPCR was 16% (48/300) among febrile patients, of which 19 (39.6%) were P. vivax, 25 (52.1%) were P. falciparum, and 4 (8.3%) were mixed (P. vivax and P. falciparum) infections. Among the 48 qPCR-positive samples, 39 (13%) were negative by microscopy. The results of bivariate logistic regression analysis showed that agriculture-related occupation, relapse and recurrence were significantly associated with Plasmodium infection (P < 0.001). Of the 300 febrile patients, 85 (28.3%) were Duffy negative, of whom two had P. vivax, six had P. falciparum, and one had mixed infections. Except for one patient with P. falciparum infection, Plasmodium infections in Duffy-negative individuals were all submicroscopic with low parasitaemia.

CONCLUSIONS

The present study revealed a high prevalence of submicroscopic malaria infections. Plasmodium vivax infections in Duffy-negative individuals were not detected due to low parasitaemia. In this study, an improved molecular diagnostic tool was used to detect and characterize Plasmodium infections, with the goal of quantifying P. vivax infection in Duffy-negative individuals. Advanced molecular diagnostic techniques, such as multiplex real-time PCR, loop-mediated isothermal amplification (LAMP), and CRISPR-based diagnostic methods. These techniques offer increased sensitivity, specificity, and the ability to detect low-parasite-density infections compared to the employed methodologies.

Insight into Increased Recovery and Simplification of Genomic DNA Extraction Methods from Dried Blood Spots

There is no consensus on how to perform the manual extraction of nucleic acids from dried blood spots (DBSs). Current methods typically involve agitation of the DBSs in a solution for varying amounts of time with or without heat, and then purification of the eluted nucleic acids with a purification protocol. We explored several characteristics of genomic DNA (gDNA) DBS extraction such as extraction efficiency, the role of red blood cells (RBCs) in extraction and critical kinetic factors to understand if these protocols can be simplified while maintaining sufficient gDNA recovery. We found that agitation in a RBC lysis buffer before performing a DBS gDNA extraction protocol increases yield 1.5 to 5-fold, depending upon the anticoagulant used. The use of an alkaline lysing agent along with either heat or agitation was sufficient to elute quantitative polymerase chain reaction (qPCR) amplifiable gDNA in 5 minutes. This work adds insight into the extraction of gDNA from DBSs with the intention of informing a simple, standardized manual protocol for extraction.

Haptoglobin gene polymorphism and iron profile in sickle cell disease patients with inflammation in Yaounde, Cameroon

BACKGROUND

Major sickle cell syndromes are the most common hemoglobinopathy in the world. The sickle cell patients are subjected to several factors causing inflammation, and the genetic identification of each individual allows to focus the possibility of allelic variations influence of a specific gene and then the polymorphism. This study aims at determining the distribution of HP gene (OMIM#140100) and their involvement on hematological parameters and the iron profile in the sickle cell patients presenting an inflammation condition during major sickle cell syndromes in Cameroun.

METHODS

A case-control analytical study has been conducted over a period of 6 months. Cases consisting of sickle cell patients in a situation of inflammation and control of non-inflamed sickle cell patients. The patients presenting major sickle cell syndromes, interned and/or followed at the Hematology Department of the Regional Hospital of Bafoussam and the Central Hospital of Yaoundé have been recruited. HP genotyping was carried out at the Laboratory for Public Health Research Biotechnologies (LAPHER-Biotech) in Yaoundé using allele-specific PCR. Also, inflammatory, hematological parameters and martial assessment were explored by standard methods. Statistical analysis of the data was performed using the statistical tool R version 4.1.1. The comparison of proportions of alleles was made with the chi-square test, and the Wilcoxon test was used to compare the median between different groups using the statistical tool R version 4.1.1.

RESULTS

We analyzed the samples of 149 patients. The HP polymorphism describes a significant frequency of the "1F" allele (69.8%) followed by the "2" allele (46.31%). In addition, 80 patients (53.69%), 48 (32.21%), and 21 (14.09%) presented the genotype HP 1-1, HP 2-1, and HP 2-2, respectively. And eighty-one percent (81%) patients with genotype HP 2-2 showed a significant higher relative frequency of thrombocytosis compared with the genotype HP 1-1 and HP 2-1, respectively (51.2% and 68.8%, p = 0.087). The proportion of inflammation in the HP 2-2 group was higher (57.1%) compared with the other groups (respectively 42.5% and 35.4% in the HP 1-1 and HP 2-1 groups). Furthermore, the median CRP was significantly higher in the HP 2-2 group compared with the other groups (p = 0.039). Moreover, the entire population of the HP 2-2 group showed an elevation of ferritin and IL6 unlike the HP 1-1 and HP 2-1 groups.

CONCLUSION

This study demonstrates a higher frequency of genotype HP 1-1 followed by the HP 2-2 genotype in patients with major sickle cell syndromes. However, a larger proportion of patients with genotype HP 2-2 are associated with hematological profile disorders, inflammation, and dysregulation of iron metabolism. Then, the haptoglobin polymorphism contributes to the severity of major sickle cell syndromes.

Haptoglobin gene polymorphism and iron profile in sickle cell disease patients with inflammation in Yaounde, Cameroon

Background

Major sickle cell syndromes are the most common hemoglobinopathy in the world. The sickle cell patients are subjected to several factors causing inflammation, and the genetic identification of each individual allows to focus the possibility of allelic variations influence of a specific gene and then the polymorphism. This study aims at determining the distribution of HP gene (OMIM#140100) and their involvement on hematological parameters and the iron profile in the sickle cell patients presenting an inflammation condition during major sickle cell syndromes in Cameroun.

Methods

A case–control analytical study has been conducted over a period of 6 months. Cases consisting of sickle cell patients in a situation of inflammation and control of non‐inflamed sickle cell patients. The patients presenting major sickle cell syndromes, interned and/or followed at the Hematology Department of the Regional Hospital of Bafoussam and the Central Hospital of Yaoundé have been recruited. HP genotyping was carried out at the Laboratory for Public Health Research Biotechnologies (LAPHER‐Biotech) in Yaoundé using allele‐specific PCR. Also, inflammatory, hematological parameters and martial assessment were explored by standard methods. Statistical analysis of the data was performed using the statistical tool R version 4.1.1. The comparison of proportions of alleles was made with the chi‐square test, and the Wilcoxon test was used to compare the median between different groups using the statistical tool R version 4.1.1.

Results

We analyzed the samples of 149 patients. The HP polymorphism describes a significant frequency of the “1F” allele (69.8%) followed by the “2” allele (46.31%). In addition, 80 patients (53.69%), 48 (32.21%), and 21 (14.09%) presented the genotype HP 1‐1, HP 2‐1, and HP 2‐2, respectively. And eighty‐one percent (81%) patients with genotype HP 2‐2 showed a significant higher relative frequency of thrombocytosis compared with the genotype HP 1‐1 and HP 2‐1, respectively (51.2% and 68.8%, p = 0.087). The proportion of inflammation in the HP 2‐2 group was higher (57.1%) compared with the other groups (respectively 42.5% and 35.4% in the HP 1‐1 and HP 2‐1 groups). Furthermore, the median CRP was significantly higher in the HP 2‐2 group compared with the other groups (p = 0.039). Moreover, the entire population of the HP 2‐2 group showed an elevation of ferritin and IL6 unlike the HP 1‐1 and HP 2‐1 groups.

Conclusion

This study demonstrates a higher frequency of genotype HP 1‐1 followed by the HP 2‐2 genotype in patients with major sickle cell syndromes. However, a larger proportion of patients with genotype HP 2‐2 are associated with hematological profile disorders, inflammation, and dysregulation of iron metabolism. Then, the haptoglobin polymorphism contributes to the severity of major sickle cell syndromes.

Detection of Duffy Blood Group Genotypes and Submicroscopic Plasmodium Infections Using Molecular Diagnostic Assays in Febrile Malaria Patients

Background

Malaria remains a severe parasitic disease, posing a significant threat to public health and hindering economic development in sub-Saharan Africa. Ethiopia, a malaria endemic country, is facing a resurgence of the disease with a steadily rising incidence. Conventional diagnostic methods, such asmicroscopy, have become less effective due to low parasite density, particularly among Duffy-negative human populations in Africa. To develop comprehensive control strategies, it is crucial to generate data on the distribution and clinical occurrence of Plasmodium vivax and P. falciparum infections in regions where the disease is prevalent. This study assessed Plasmodium infections and Duffy antigen genotypes in febrile patients in Ethiopia.

Methods

Three hundred febrile patients visiting four health facilities in Jimma town of southwestern Ethiopia were randomly selected during the malaria transmission season (Apr-Oct). Sociodemographic information was collected, and microscopic examination was performed for all study participants. Plasmodiumspecies and parasitemia as well as the Duffy genotype were assessed by quantitative polymerase chain reaction (qPCR) for all samples. Data were analyzed using Fisher's exact test and kappa statistics.

Results

The Plasmodium infection rate by qPCR was 16% (48/300) among febrile patients, of which 19 (39.6%) were P. vivax, 25 (52.1%) were P. falciparum, and 4 (8.3%) were mixed (P. vivax and P. falciparum) infections. Among the 48 qPCR-positive samples, 39 (13%) were negative by microscopy. The results of bivariate logistic regression analysis showed that agriculture-related occupation, relapse and recurrence were significantly associated withPlasmodium infection (P<0.001). Of the 300 febrile patients, 85 (28.3%) were Duffy negative, of whom two had P. vivax, six had P. falciparum, and one had mixed infections.Except for one patient with P. falciparum infection, Plasmodium infections in Duffy-negative individuals were all submicroscopic with low parasitemia.

Conclusions

The present study revealed a high prevalence of submicroscopic malaria infections. Plasmodium vivax infections in Duffy-negative individuals were not detected due to low parasitemia. Here, we recommend an improved molecular diagnostic tool to detect and characterize plasmodium infections, with the goal of quantifyingP. vivax infection in Duffy-negative individuals.

Effect of storage temperature and duration on direct PCR amplification of various feather types and DBS matrices

The use of direct PCR has been pioneered over the last decade for DNA analysis of biological specimens of distinct origins. The information on how longer these specimens can be stored and amplified by direct PCR is however scanty. Such a piece of information could expedite research and diagnostic studies without compromising the reliability of results. The current study was therefore designed to analyze the effect of storage temperature and duration on direct PCR amplification of biological specimens having either low quantity or high quantity of DNA. Whole blood, dried blood spots (DBS), and feathers from chicken were stored for five years at three different temperatures, viz. room temperature (∼25 °C), 4 °C, and -20 °C. These samples were subjected to crude DNA extraction by diluting them in PBS buffer and heating at 98 °C after 1 day, 7 days, 15 days, 1 month, 3 months, 6 months, 1 year, 3 years and 5 years of storage. The crude DNA was PCR-amplified with the use of DNA sexing primers as well as DNA barcoding primers. Incubation at 98 °C for 10 min of any type of sample in PBS buffer was sufficient for crude DNA extraction. There was irrelevant impact of feather type, DBS matrix nature and storage temperature on amplification success over the period of analysis. It was possible to successfully accomplish the amplification of 96 samples with the use of routine PCR reagents within 3.5-6.0 hrs. In short, economical and fast genetic analysis of commonly used avian samples is feasible after their storage for longer time at room temperature.

Improvement of bovine pestiviral diagnosis by the development of a cost-effective method for detecting viral RNA in fresh specimens and samples spotted in filter papers

Bovine pestiviruses are the causative agents of bovine viral diarrhea, a disease that causes severe economic losses in cattle. The aim of this study was to improve their diagnosis by developing a RT-qPCR to detect bovine pestiviruses A, B and H; and to set up a protocol for collecting, shipping and preserving bovine pestiviral RNA on filter papers. The developed RT-qPCR showed high sensitivity in detecting these viruses in different matrices: viral stocks, semen and serum samples. With regard to the possibility of using the technique to test serum pools, it was possible to identify a positive serum sample within a pool containing 30 sera. In addition to evaluating the qPCR from fresh samples, the use of filter papers to sow bovine samples was analyzed. The sampling method on two different filter papers using bovine blood drops was a useful alternative for diagnostic purposes and allowed to preserve pestiviral RNA for up to 12 months under refrigeration.

CRISPR-Based Diagnostics: Challenges and Potential Solutions toward Point-of-Care Applications

The COVID-19 pandemic has challenged the conventional diagnostic field and revealed the need for decentralized Point of Care (POC) solutions. Although nucleic acid testing is considered to be the most sensitive and specific disease detection method, conventional testing platforms are expensive, confined to central laboratories, and are not deployable in low-resource settings. CRISPR-based diagnostics have emerged as promising tools capable of revolutionizing the field of molecular diagnostics. These platforms are inexpensive, simple, and do not require the use of special instrumentation, suggesting they could democratize access to disease diagnostics. However, there are several obstacles to the use of the current platforms for POC applications, including difficulties in sample processing and stability. In this review, we discuss key advancements in the field, with an emphasis on the challenges of sample processing, stability, multiplexing, amplification-free detection, signal interpretation, and process automation. We also discuss potential solutions for revolutionizing CRISPR-based diagnostics toward sample-to-answer diagnostic solutions for POC and home use.

Population genomics of a predatory mammal reveals patterns of decline and impacts of exposure to toxic toads

Mammal declines across northern Australia are one of the major biodiversity loss events occurring globally. There has been no regional assessment of the implications of these species declines for genomic diversity. To address this, we conducted a species-wide assessment of genomic diversity in the northern quoll (Dasyurus hallucatus), an Endangered marsupial carnivore. We used next generation sequencing methods to genotype 10,191 single nucleotide polymorphisms (SNPs) in 352 individuals from across a 3220-km length of the continent, investigating patterns of population genomic structure and diversity, and identifying loci showing signals of putative selection. We found strong heterogeneity in the distribution of genomic diversity across the continent, characterized by (i) biogeographical barriers driving hierarchical population structure through long-term isolation, and (ii) severe reductions in diversity resulting from population declines, exacerbated by the spread of introduced toxic cane toads (Rhinella marina). These results warn of a large ongoing loss of genomic diversity and associated adaptive capacity as mammals decline across northern Australia. Encouragingly, populations of the northern quoll established on toad-free islands by translocations appear to have maintained most of the initial genomic diversity after 16 years. By mapping patterns of genomic diversity within and among populations, and investigating these patterns in the context of population declines, we can provide conservation managers with data critical to informed decision-making. This includes the identification of populations that are candidates for genetic management, the importance of remnant island and insurance/translocated populations for the conservation of genetic diversity, and the characterization of putative evolutionarily significant units.

Ultrasensitive qPCR-Based Detection of Plasmodium falciparum in Pregnant Women Using Dried Blood or Whole Blood Pellet Samples Processed through Different DNA Extraction Methods

Highly sensitive molecular techniques for the detection of low-level Plasmodium falciparum parasitemia are highly useful for various clinical and epidemiological studies. However, differences in how blood samples are preserved, the quantity of blood stored, as well as genomic DNA extraction methods used may compromise the potential usefulness of these methodologies. This study compared diagnostic sensitivity based on microscopy and malaria rapid diagnostic tests (mRDTs), with quantitative polymerase chain reaction (qPCR) P. falciparum positivity of dried blood spots (DBS) or whole blood pellets (WBP) from pregnant women using different DNA extraction protocols (Chelex-saponin or a commercial kit). Samples from 129 pregnant women were analyzed, of which 13 were P. falciparum positive by mRDT and 5 by microscopy. By using extraction kit on WBP and on DBS, qPCR positivity was 27 (20.9%) and 16 (12.4%), respectively, whereas Chelex extraction on DBS only resulted in 4 (3.1%) P. falciparum positive samples. Thus, extraction using commercial kits greatly improve the likelihood of detecting P. falciparum infections.

Towards Next-Generation Sequencing (NGS)-Based Newborn Screening: A Technical Study to Prepare for the Challenges Ahead

Newborn screening (NBS) aims to identify neonates with severe conditions for whom immediate treatment is required. Currently, a biochemistry-first approach is used to identify these disorders, which are predominantly inherited meta1bolic disorders (IMD). Next-generation sequencing (NGS) is expected to have some advantages over the current approach, for example the ability to detect IMDs that meet all screening criteria but lack an identifiable biochemical footprint. We have now designed a technical study to explore the use of NGS techniques as a first-tier approach in NBS. Here, we describe the aim and set-up of the NGS-first for the NBS (NGSf4NBS) project, which will proceed in three steps. In Step 1, we will identify IMDs eligible for NGS-first testing, based on treatability. In Step 2, we will investigate the feasibility, limitations and comparability of different technical NGS approaches and analysis workflows for NBS, eventually aiming to develop a rapid NGS-based workflow. Finally, in Step 3, we will prepare for the incorporation of this workflow into the existing Dutch NBS program and propose a protocol for referral of a child after a positive NGS test result. The results of this study will be the basis for an additional analytical route within NBS that will be further studied for its applicability within the NBS program, e.g., regarding the ethical, legal, financial and social implications.

The genome of the zoonotic malaria parasite Plasmodium simium reveals adaptations to host switching

BACKGROUND

Plasmodium simium, a malaria parasite of non-human primates (NHP), was recently shown to cause zoonotic infections in humans in Brazil. We sequenced the P. simium genome to investigate its evolutionary history and to identify any genetic adaptions that may underlie the ability of this parasite to switch between host species.

RESULTS

Phylogenetic analyses based on whole genome sequences of P. simium from humans and NHPs reveals that P. simium is monophyletic within the broader diversity of South American Plasmodium vivax, suggesting P. simium first infected NHPs as a result of a host switch of P. vivax from humans. The P. simium isolates show the closest relationship to Mexican P. vivax isolates. Analysis of erythrocyte invasion genes reveals differences between P. vivax and P. simium, including large deletions in the Duffy-binding protein 1 (DBP1) and reticulocyte-binding protein 2a genes of P. simium. Analysis of P. simium isolated from NHPs and humans revealed a deletion of 38 amino acids in DBP1 present in all human-derived isolates, whereas NHP isolates were multi-allelic.

CONCLUSIONS

Analysis of the P. simium genome confirmed a close phylogenetic relationship between P. simium and P. vivax, and suggests a very recent American origin for P. simium. The presence of the DBP1 deletion in all human-derived isolates tested suggests that this deletion, in combination with other genetic changes in P. simium, may facilitate the invasion of human red blood cells and may explain, at least in part, the basis of the recent zoonotic infections.

Long-Term Preservation and Storage of Faecal Samples in Whatman® Cards for PCR Detection and Genotyping of Giardia duodenalis and Cryptosporidium hominis

Preservation and conservation of biological specimens, including faecal samples, is a challenge in remote areas or poor-resource settings where the cold chain cannot be maintained. This study aims at evaluating the suitability of filter cards for long-term storage of faecal samples of animal and human origin positive to the diarrhoea-causing protozoan parasites, Giardia duodenalis and Cryptosporidium hominis. Three commercially available Whatman^® Filter Cards were comparatively assessed: the FTA^® Classic Card, the FTA^® Elute Micro Card, and the 903 Protein Saver Card. Human faecal samples positive to G. duodenalis (n = 5) and C. hominis (n = 5) were used to impregnate the selected cards at given storage (1 month, 3 months, and 6 months) periods and temperature (-20 °C, 4 °C, and room temperature) conditions. Parasite DNA was detected by PCR-based methods. Sensitivity assays and quality control procedures to assess suitability for genotyping purposes were conducted. Overall, all three Whatman^® cards were proven useful for the detection and molecular characterisation of G. duodenalis and C. hominis under the evaluated conditions. Whatman^® cards represent a simple, safe, and cost-effective option for the transportation, preservation, and storage of faecal samples without the need of the cold chain.

Molecular Investigation on Tick-Borne Hemoparasites and Coxiella burnetii in Dromedary Camels (Camelusdromedarius) in Al Dhafra Region of Abu Dhabi, UAE

Camels represent an important resource for inhabitants of the most arid regions of the world and their survival is mainly related to environment conditions including the risk of parasitic diseases, which may represent a significant cause of losses in livestock production of these areas. Camels may be parasitized by several hematophagous arthropods, which can be vectors of several diseases including zoonosis. This study aimed to investigate in dromedary camels and their ticks the importance of tick-borne hemoparasites that might be responsible for a recent and obscure morbidity of camels in Al Dhafra region of Abu Dhabi, UAE. Blood samples and ticks from 93 naturally infected camels belonging to 36 herds, affected by variable acute clinical syndromes lasting from 3 to 5 days, were analyzed through molecular techniques for specific DNA presence of different blood pathogens: Anaplasmamarginale/Anaplasmaovis, Anaplasma phagocytophilum, Coxiella burnetii,Babesia spp., and Theileria spp. DNA. All the 72 ticks collected belonged to the Hyalomma dromedarii species and were negative for blood pathogens. n = 15 camels (16.1%) were found positive to the following tick-borne hemoparasites: A. phagocytophilum 11 (11.8%), Coxiella burnetii 3 (3.2%), and Babesia/Theileria spp. 2 (2.1%). One singular camel showed coinfection of C. burnetii and A. phagocytophiulm. Genetic profile of C. burnetii showed a high phylogenetic relatedness to European, Asian and African C. burnetii strains. This is the first laboratory investigation on tick-borne pathogens in camels in UAE, and the first report of A. phagocytophilum and C. burnetii. Moreover, since the detected pathogens are recognized pathogens for humans, this study highlights the zoonotic risk for humans working in camel husbandry.

Detection of Schistosoma mansoni DNA using polymerase chain reaction from serum and dried blood spot card samples of an adult population in North-western Tanzania

BACKGROUND

Real-time polymerase chain reaction (PCR) is a sensitive and specific method for diagnosing schistosomiasis. However, this method should be performed in a laboratory, usually located distant from the sample collection site. Therefore, it is important to have fast sampling preservation methods, which allow simple transport prior to DNA extraction and amplification. The aim of this study was to verify if blood samples applied to filter paper are suitable for analysis of Schistosoma mansoni DNA by real-time PCR.

METHODS

A cross-sectional study was conducted among 100 study participants aged 17 to 70 years in a fishing village on the southern shore of Lake Victoria, Tanzania. Serum samples and ethylenediaminetetraacetic acid (EDTA)-anticoagulated whole blood for preparation of dried blood spots (DBS) were collected to test for Schistosoma mansoni infection by real-time PCR. A combined diagnostic reference of positive results of serum-based real-time PCR and the Kato-Katz (KK) method was used for analysis. Sensitivity and negative predictive value (NPV) were calculated. The Wilcoxon signed-rank test was chosen to compare the mean cycle threshold (Ct) values from serum and DBS.

RESULTS

According to the reference, 92.5% S. mansoni positive samples were determined. The serum-based real-time PCR performed excellently with 95.4% sensitivity, whereas the DBS-based real-time PCR showed a low sensitivity (45.4%). The Ct-values were significantly higher in DBS (median: 37.3) than in serum samples (median: 27.5, P < 0.001), reflecting a lower parasite-specific DNA load on the filter cards. With increasing egg counts, an increase in sensitivity was observed for all methods. The POC-CCA test and the serum-based real-time PCR showed a sensitivity of 100% for medium and severe infections. The DBS real-time PCR showed a sensitivity of only 85.7% even for severe infections.

CONCLUSIONS

DBS-based real-time PCR did not provide good results in our study and therefore should not be recommended or must be tested concerning temperature of storage, storage duration, use of different filter papers and extraction methods before it is used in future studies. In contrast, our results showed that the POC-CCA test is a sensitive and precise test for detecting S. mansoni infections .

Mind the Quality Gap When Banking on Dry Blood Spots

Dry blood spots (DBS) offer many advantages over other blood banking protocols due to the reduction of time and equipment needed for collection and the ease of processing, storage, and shipment. In addition, the sample size makes it a very attractive method when considering the banking of small pediatric samples. On that note, the Centers for Disease Control and Prevention (CDC) preanalytical standards for DBS are commonly used in the worldwide mass spectrometry-based inborn errors of metabolism screening programs. However, these guidelines may not apply for analytes and protocols not included in these programs. In fact, the availability of leftover samples and the ongoing interest in protocols outside this scenario are providing us with new DBS biobanking insights. Herein, we review the literature for indicators that should be considered in the design of prospective fit for purpose DBS biobanks, especially for those focused mostly on pediatric and OMIC platforms.

Development of novel extraction reagents for analyzing dried blood spots from crime scenes

Evidence of dried blood is very valuable in forensic science. Since the discovery of luminescence with Luminol and dried blood spots (DBSs) in 1928, interest and research on blood have continued to date. One of the most important factor that DBSs have is genes. However, the current use of distilled water (DDW) to collect and extract blood samples has disadvantages related to DNA stability. Therefore, this study aimed to develop an extraction reagent that is most suitable for gene extraction from DBSs. Blood was collected from 45 healthy adult men and women in vacuum blood containers without coagulants or anticoagulants. The collected blood was dried in various settings to check the performance of the extraction reagent. Extraction with Tris-EDTA (TE) and phosphate-buffered saline (PBS) was found more suitable in terms of gene interference effects compared with DDW; their performance was also compared with those of the newly developed extraction reagents. Upon comparing the results of polymerase chain reaction for human genomic DNA samples using glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene as the target, the performance of the newly developed extraction reagents, modified TE and PBS, was found to be relatively good. To determine the optimal composition of the developed extraction reagents, 12 new extraction reagents were developed with different pH and sodium concentrations. Among them, the best results were found when the DNA was extracted using extraction reagent No. 3 with pH 8.0 and containing 1 M NaCl. Next, the four extraction reagents, DDW, TE, PBS, and No. 3 were compared under nine different temperature and humidity conditions. Similarly, under various environmental conditions, extraction reagent No. 3 performed better than other reagents. It is proposed that modified TE and PBS mixed extraction reagents are the most suitable for collecting and preserving crime site samples. The proposed composition for a DNA extraction reagent can contribute greatly to crime scene reconstruction.

Development of a Multiplex Loop-Mediated Isothermal Amplification (LAMP) Method for Simultaneous Detection of Spotted Fever Group Rickettsiae and Malaria Parasites by Dipstick DNA Chromatography

Spotted fever group (SFG) rickettsiae causes febrile illness in humans worldwide. Since SFG rickettsiosis’s clinical presentation is nonspecific, it is frequently misdiagnosed as other febrile diseases, especially malaria, and complicates proper treatment. Aiming at rapid, simple, and simultaneous detection of SFG Rickettsia spp. and Plasmodium spp., we developed a novel multiple pathogen detection system by combining a loop-mediated isothermal amplification (LAMP) method and dipstick DNA chromatography technology. Two primer sets detecting SFG Rickettsia spp. and Plasmodium spp. were mixed, and amplified products were visualized by hybridizing to dipstick DNA chromatography. The multiplex LAMP with dipstick DNA chromatography distinguished amplified Rickettsia and Plasmodium targeted genes simultaneously. The determined sensitivity using synthetic nucleotides was 1000 copies per reaction for mixed Rickettsia and Plasmodium genes. When genomic DNA from in vitro cultured organisms was used, the sensitivity was 100 and 10 genome equivalents per reaction for Rickettsia monacensis and Plasmodium falciparum, respectively. Although further improvement will be required for more sensitive detection, our developed simultaneous diagnosis technique will contribute to the differential diagnosis of undifferentiated febrile illness caused by either SFG Rickettsia spp. or Plasmodium spp. in resource-limited endemic areas. Importantly, this scheme is potentially versatile for the simultaneous detection of diverse infectious diseases.

Ethnicity, age and disease-associated variation in body fluid-specific CpG sites in a diverse South African cohort

Tissue-specific differential DNA methylation has been an attractive target for the development of markers for discrimination of body fluids found at crime scenes. Though mostly stable, DNA methylation patterns have been shown to vary between different ethnic groups, in different age groups as well as between healthy and diseased individuals. To the best of our knowledge, none of the markers for body fluid identification have been applied to different ethnic groups to ascertain if variability exists. In the present study, saliva and blood were collected to determine the effects of ethnicity (Blacks, Whites, Coloureds and Indians), age (20-30 years, 40-50years and above 60 years) and diabetes on methylation profiles of potential saliva- and blood-specific DMSs. Both DMSs were previously shown to exhibit hypermethylation in their target body fluids at single CpG sites, however in the present study, additional CpG sites flanking the reported sites were also screened. Bisulfite sequencing revealed that Coloureds showed highest methylation levels for both body fluids, and blacks displayed significant differences between other ethnic groups in the blood-specific CpG sites. A decline in methylation for both potential DMRs was observed with increasing age. Heavily methylated CpG sites in different ethnic groups and previously reported DMSs displayed hypomethylation with increasing age and disease status. Diabetic status did not show any significant difference in methylation when compared to healthy counterparts. Thus, the use of methylation markers for forensics needs thorough investigation of influence of external factors and ideally, several CpG sites should be co-analysed instead of a single DMS.

Gene doping and genomic science in sports: where are we?

The misuse of sport-related gene transfer methods in elite athletes is a real and growing concern. The success of gene therapy in the treatment of hereditary diseases has been most evident since targets in gene therapy products can be used in healthy individuals to improve sports performance. Performing these practices threatens the sporting character of competitions and may pose potential health hazards. Since the World Anti-Doping Agency pronouncement on the prohibition of such practices in 2003, several researchers have been trying to address the challenge of developing an effective method for the detection of genetic doping. This review presents an overview of the published methods developed for this purpose, the advantages and limitations of technologies and the putative target genes. At last, we present the perspective related to the application of the detection methods in the doping control field.

Utilization of archived neonatal dried blood spots for genome-wide genotyping

Introduction

Heel pricks are performed on newborns for diagnostic screenings of various pre-symptomatic metabolic and genetic diseases. Excess blood is spotted on Guthrie cards and archived by many states in biobanks for follow-up diagnoses and public health research. However, storage environment may vary across biobanks and across time within biobanks. With increased applications of DNA extracted from spots for genetic studies, identifying factors associated with genotyping success is critical to maximize DNA quality for future studies.

Method

We evaluated 399 blood spots, which were part of a genome-wide association study of childhood leukemia risk in children with Down syndrome, archived at the Michigan Neonatal Biobank between 1992 and 2008. High quality DNA was defined as having post-quality control call rate ≥ 99.0% based on the Illumina GenomeStudio 2.0 GenCall algorithm after processing the samples on the Illumina Infinium Global Screening Array. Bivariate analyses and multivariable logistic regression models were applied to evaluate effects of storage environment and storage duration on DNA genotyping quality.

Results

Both storage environment and duration were associated with sample genotyping call rates (p-values < 0.001). Sample call rates were associated with storage duration independent of storage environment (p-trend = 0.006 for DBS archived in an uncontrolled environment and p-trend = 0.002 in a controlled environment). However, 95% of the total sample had high genotyping quality with a call rate ≥ 95.0%, a standard threshold for acceptable sample quality in many genetic studies.

Conclusion

Blood spot DNA quality was lower in samples archived in uncontrolled storage environments and for samples archived for longer durations. Still, regardless of storage environment or duration, neonatal biobanks including the Michigan Neonatal Biobanks can provide access to large collections of spots with DNA quality acceptable for most genotyping studies.

Optimization of extraction of genomic DNA from archived dried blood spot (DBS): potential application in epidemiological research & bio banking

Background: Limited infrastructure is available to collect, store and transport venous blood in field epidemiological studies. Dried blood spot (DBS) is a robust potential alternative sample source for epidemiological studies & bio banking. A stable source of genomic DNA (gDNA) is required for long term storage in bio bank for its downstream applications. Our objective is to optimize the methods of gDNA extraction from stored DBS and with the aim of revealing its utility in large scale epidemiological studies.  Methods: The purpose of this study was to extract the maximum amount of gDNA from DBS on Whatman 903 protein saver card. gDNA was extracted through column  (Qiagen) & magnetic bead based (Invitrogen) methods. Quantification of extracted gDNA was performed with a spectrophotometer, fluorometer, and integrity analyzed by agarose gel electrophoresis.  Result: Large variation was observed in quantity & purity (260/280 ratio, 1.8-2.9) of the extracted gDNA. The intact gDNA bands on the electrophoresis gel reflect the robustness of DBS for gDNA even after prolonged storage time. The extracted gDNA amount 2.16 - 24 ng/µl is sufficient for its PCR based downstream application, but unfortunately it can't be used for whole genome sequencing or genotyping from extracted gDNA. Sequencing or genotyping can be achieved by after increasing template copy number through whole genome amplification of extracted gDNA. The obtained results create a base for future research to develop high-throughput research and extraction methods from blood samples. Conclusion: The above results reveal, DBS can be utilized as a potential and robust sample source for bio banking in field epidemiological studies.

Optimization of extraction of genomic DNA from archived dried blood spot (DBS): potential application in epidemiological research & bio banking

Background: Limited infrastructure is available to collect, store and transport venous blood in field epidemiological studies. Dried blood spot (DBS) is a robust potential alternative sample source for epidemiological studies & bio banking. A stable source of genomic DNA (gDNA) is required for long term storage in bio bank for its downstream applications. Our objective is to optimize the methods of gDNA extraction from stored DBS and with the aim of revealing its utility in large scale epidemiological studies. 

Methods: The purpose of this study was to extract the maximum amount of gDNA from DBS on Whatman 903 protein saver card. gDNA was extracted through column  (Qiagen) & magnetic bead based (Invitrogen) methods. Quantification of extracted gDNA was performed with a spectrophotometer, fluorometer, and integrity analyzed by agarose gel electrophoresis. 

Result: Large variation was observed in quantity & purity (260/280 ratio, 1.8-2.9) of the extracted gDNA. The intact gDNA bands on the electrophoresis gel reflect the robustness of DBS for gDNA even after prolonged storage time. The extracted gDNA amount 2.16 – 24 ng/µl is sufficient for its PCR based downstream application, but unfortunately it can’t be used for whole genome sequencing or genotyping from extracted gDNA. Sequencing or genotyping can be achieved by after increasing template copy number through whole genome amplification of extracted gDNA. The obtained results create a base for future research to develop high-throughput research and extraction methods from blood samples.

Conclusion: The above results reveal, DBS can be utilized as a potential and robust sample source for bio banking in field epidemiological studies.

A handmade DNA extraction kit using laundry powder; insights on simplicity, cost-efficiency, rapidity, safety and the quality of purified DNA

Here we describe an in-house kit for high throughput DNA extraction using laundry detergent. A simplified lysis buffer made only from 0.08 M EDTA, 0.1 M Tris, and laundry powder is the core of our protocol. We extracted genomic DNA from 150 µL of whole blood collected from different farm animals and compared the performance to both the DNeasy Blood & Tissue Kit (Qiagen) and the widely used salting-out procedure. An evaluation of the concentration and quality of the extracted DNA was then assessed by the NanoDrop absorption spectra, agarose gel migration, amplification in PCR and the Sanger sequencing. The in-house kit successfully extracted clean DNA from all blood samples, and discernably outperformed the commercial kits and the original salting-out procedure in the sense of the simplicity, cost-efficiency, quantity, and the quality of purified DNA. Apart from replacing proteinase K and the sodium dodecyl sulfate treatment by the laundry detergent, our protocol instructs a lysis buffer that eliminates sucrose, Triton X-100, MgCl₂, NH₄Cl, and KCl. Our handmade kit might be of interest for laboratories in underdeveloped countries with a budget shortage or applications in difficult field conditions, for example, when fridge storage for proteinase K cannot be ensured.

Evaluation of commercial methods to separate nucleic acids from intestinal tissues of pigs for diagnosis of porcine epidemic diarrhea

The article presents the results of evaluating commercial methods for extracting nucleic acids from pig intestinal tissues for the diagnosis of PED. The study was based on samples of small intestine tissues and faeces from 3–5 day old pigs which died from PED. Nucleic acid extraction was performed using commercial kits with different nucleic acid separation strategies based on: silicon-sorbent; silicate membrane fixed in a microcentrifuge column and magnetic balls. The studies were conducted in two stages. The first was a comparison of the results of the amplification of the obtained nucleic acid extracts from the homogenate of the intestines of piglets by using the above-mentioned commercial kits for the extraction of nucleic acids. For this purpose, samples of homogenate were used which in weight corresponded to the guideline for the application of the test kits. The second step was directed to determining the efficiency of extraction of DNA and RNA from homogenate samples with a weight of 10, 50, 100 and 200 mg. Determination of the optimal methodological strategy of nucleic acid extraction for the diagnosis of porcine epidemic diarrhea by PCR has been investigated. The results of the PCR studies of RNA of the PED virus and a unique pig DNA fragment indicate that the extraction of nucleic acids by commercial kits has different levels of efficiency and depends on different factors. According to the research, it was found that the most important of them are the adsorption capacity of the solid-phase sorbent, its configuration and nature, which binds RNA and DNA molecules, the type of sample from which extraction takes place, its volume, or the tissue mass used for extraction. Based on the obtained results, it has been found that the most effective PED virus RNA extraction is by “ArtBioTech”, “Bio Extract Column”, and “Viral DNA/RNA Extraction Kit”, and pig genomic DNA extraction by the “ArtBioTech” and “Viral DNA / RNA extraction Kit”.

Evaluation of methods for detection of asymptomatic individuals infected with Leishmania infantum in the state of Piauí, Brazil

BACKGROUND

Visceral Leishmaniasis in humans presents with fever, anemia, and splenomegaly and can be lethal if not treated. Nevertheless, the majority of Leishmania infantum-infected individuals does not manifest symptoms and remain so provided they are not immunosuppressed. In this work, the performance of different tests was evaluated to detect asymptomatic individuals who were living in Teresina, Piauí state, Brazil, an endemic area for VL.

METHODOLOGY

L. infantum-specific antibodies were detected by ELISA and two different rapid immunochromatographic (IC) diagnostic tests, Kalazar Detect and OnSite, and parasitic loads were detected by real time PCR [qPCR]. Additionally, we measured levels of the biomarkers monokine induced by IFN-γ (MIG) and IFN-γ-induced protein 10 (IP-10) before and after stimulation of whole blood with soluble Leishmania antigen [SLA].

PRINCIPAL FINDINGS

Kalazar Detect and OnSite detected, respectively, 76% and 64% of patients presenting with active Visceral Leishmaniasis; 50% and 57% of patients remained positive in these tests, respectively, after treatment. Of the healthy participants in the study who were living in the endemic area, only 1.7% were positive with both of the IC tests. On the other hand, reactivity in ELISA tests revealed that 13% of these individuals presented asymptomatic infections; among VL patients, 84% presenting with active disease were reactive in ELISA, and after treatment, 55.5% were seropositive. L. infantum DNA was present in the blood of 37.9% of infected individuals living in the endemic area, while IP-10 and MIG biomarkers were detected in 26.7% of them. The greatest concordance of positivity occurred between ELISA and qPCR.

CONCLUSION

The association of different techniques can detect asymptomatic infections, however, more research is necessary to develop ideal biomarkers that are simple to use in the clinic and in field studies in areas endemic for Visceral Leishmaniasis.

Comparison between different methods of DNA isolation from dried blood spots for determination of malaria to determine specificity and cost effectiveness

DNA extraction from filter paper by using different methods was compiled through a thorough review of many research articles published in various journals. When performing malaria epidemiological surveys in remote area, it is difficult to collect blood samples and transport it. In field particularly in remote area where facilities for storing and processing of samples does not exist, there surveillance and diagnosis of malaria is very difficult. In this review we are focused upon four simple methods of DNA isolation from the field collected blood and mosquito abdomen blood meal spotted on Whatman No. 1 or No. 3 filter paper. The main DNA isolation methods are Chelex-100, Tris-EDTA (TE) buffer; Methanol based DNA extraction and Phosphate buffer saline (PBS) using Lysis buffer and Phenol-Chloroform method. Efforts have been taken to identify the methods which are cost-effective and take less time to extract DNA from dried blood spots (DBS) and whole mosquitoes. The purpose of this paper is to update the knowledge and find a method to extract DNA from DBS which will be specific, rapid, cost-effective, less time consuming and feasible for epidemiological survey in remote area.

Rapid electrophoretic recovery of DNA from dried blood spots

Large-scale genetic screening of neonatal dried blood spots for episomal DNA has a great potential to lower patient mortality and morbidity through early diagnosis of primary immunodeficiencies. However, DNA extraction from the surface of dried blood spots remains one of the most time consuming, costly, and labor-intensive parts of DNA analysis. In the present study, we developed and optimized a rapid methodology using only 50 V and heat to extract episomal DNA from dried blood spots prepared from diagnostic cord blood samples. This electric field DNA extraction is the first methodology to use an electric field to extract episomal DNA from a dried blood spot. This 25-minute procedure has one of the lowest times for the extraction of episomal DNA found within the literature and this novel procedure not only negates the need for costly treatment and wash steps, but reduces the time of manual procedures by more than 30 min while retaining the 75-80% of the yield. Combined with real-time PCR, this novel method of electric field extraction not only provides an effective tool for the large scale genetic analysis of neonates, but a key step forward in the simplification and standardization of diagnostic testing.

DNA Adsorption Studies of Poly(4,4'-Cychlohexylidene Bisphenol Oxalate)/Silica Nanocomposites

The present study deals with the synthesis, characterization, and DNA extraction of poly(4,4′-cyclohexylidene bisphenol oxalate)/silica (Si) nanocomposites (NCs). The effects of varying the monomer/Si (3.7%, 7%, and 13%) ratio towards the size and morphology of the resulting NC and its DNA extraction capabilities have also been studied. For the NC synthesis, two different methods were followed, including the direct mixing of poly(4,4′-cyclohexylidene bisphenol oxalate) with fumed Si, and in situ polymerization of the 4,4′-cyclohexylidene bisphenol monomer in the presence of fumed silica (11 nm). The formed NCs were thoroughly investigated by using different techniques such as scanning electron microscopy (SEM), fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powdered X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis where the results supported that there was the successful formation of poly(4,4′-cyclohexylidene bisphenol oxalate)/Si NC. Within the three different NC samples, the one with 13% Si was found to maintain a very high surface area of 12.237 m²/g, as compared to the other two samples consisting of 7% Si (3.362 m²/g) and 3.7% Si (1.788 m²/g). Further, the solid phase DNA extraction studies indicated that the efficiency is strongly influenced by the amount of polymer (0.2 g > 0.1 g > 0.02 g) and the type of binding buffer. Among the three binding buffers tested, the guanidine hydrochloride/EtOH buffer produced the most satisfactory results in terms of yield (1,348,000 ng) and extraction efficiency (3370 ng/mL) as compared to the other two buffers of NaCl (2 M) and phosphate buffered silane. Based on our results, it can be indicated that the developed poly(4,4′-cyclohexylidene bisphenol oxalate)/Si NC can serve as one of the suitable candidates for the extraction of DNA in high amounts as compared to other traditional solid phase approaches.

Procurement, Storage, and Use of Blood in Biobanks

Blood is a widely used biospecimen in the field of biobanking, secondary to the ease with which it is collected along with the wide variety of analytes obtained from it for analysis. It carries the potential to further the search for biomarkers in countless diseases; therefore, the standardization and optimization of blood collection procedures is of importance in assuring reproducibility of results. Here, we briefly review procedures for the procurement, storage, and use of blood and its fractions for biobanking purposes. Select commonly used methods for collecting blood with various vacutainer blood collection tubes are described, along with optimal storage conditions of various samples in short- and long-term situations.

Can malaria rapid diagnostic tests by drug sellers under field conditions classify children 5 years old or less with or without Plasmodium falciparum malaria? Comparison with nested PCR analysis

Background

Malaria rapid diagnostic tests (RDTs) available as dipsticks or strips, are simple to perform, easily interpretable and do not require electricity nor infrastructural investment. Correct interpretation of and compliance with the RDT results is a challenge to drug sellers. Thus, drug seller interpretation of RDT strips was compared with laboratory scientist re-reading, and PCR analysis of Plasmodium DNA extracted from RDT nitrocellulose strips and fast transient analysis (FTA) cards. Malaria RDT cassettes were also assessed as a potential source of Plasmodium DNA.

Methods

A total of 212 children aged between 2 and 60 months, 199 of whom had complete records at two study drug shops in south western Uganda participated in the study. Duplicate 5 μL samples of capillary blood were picked from the 212 children, dispensed onto the sample well of the CareStart™ Pf-HRP2 RDT cassette and a FTA, Whatman™ 3MM filter paper in parallel. The RDT strip was interpreted by the drug seller within 15–20 min, visually re-read centrally by laboratory scientist and from it; Plasmodium DNA was recovered and detected by PCR, and compared with FTA recovered P. falciparum DNA PCR detection.

Results

Malaria positive samples were 62/199 (31.2%, 95% CI 24.9, 38.3) by drug seller interpretation of RDT strip, 59/212 (27.8%, 95% CI 22.2, 34.3) by laboratory scientist, 55/212 (25.9%, 95% CI 20.0, 32.6) by RDT nitrocellulose strip PCR and 64/212 (30.2%, 95% CI 24.4, 37.7). The overall agreement between the drug seller interpretation and laboratory scientist re-reading of the RDT strip was 93.0% with kappa value of 0.84 (95% CI 0.75, 0.92). The drug seller compliance with the reported RDT results was 92.5%. The performance of the three diagnostic strategies compared with FTA-PCR as the gold standard had sensitivity between 76.6 and 86.9%, specificity above 90%, positive predictive values ranging from 79.0 to 89.8% and negative predictive values above 90%.

Conclusion

Drug sellers can use RDTs in field conditions and achieve acceptable accuracy for malaria diagnosis, and they comply with the RDT results. Plasmodium DNA can be recovered from RDT nitrocellulose strips even in the context of drug shops. Future malaria surveillance and diagnostic quality control studies with RDT cassette as a source of Plasmodium DNA are recommended.

Electronic supplementary material

The online version of this article (10.1186/s12936-018-2508-x) contains supplementary material, which is available to authorized users.

Current Nucleic Acid Extraction Methods and Their Implications to Point-of-Care Diagnostics

Nucleic acid extraction (NAE) plays a vital role in molecular biology as the primary step for many downstream applications. Many modifications have been introduced to the original 1869 method. Modern processes are categorized into chemical or mechanical, each with peculiarities that influence their use, especially in point-of-care diagnostics (POC-Dx). POC-Dx is a new approach aiming to replace sophisticated analytical machinery with microanalytical systems, able to be used near the patient, at the point of care or point of need. Although notable efforts have been made, a simple and effective extraction method is still a major challenge for widespread use of POC-Dx. In this review, we dissected the working principle of each of the most common NAE methods, overviewing their advantages and disadvantages, as well their potential for integration in POC-Dx systems. At present, it seems difficult, if not impossible, to establish a procedure which can be universally applied to POC-Dx. We also discuss the effects of the NAE chemicals upon the main plastic polymers used to mass produce POC-Dx systems. We end our review discussing the limitations and challenges that should guide the quest for an efficient extraction method that can be integrated in a POC-Dx system.

Dosage of Sex Chromosomal Genes in Blood Deposited on Filter Paper for Neonatal Screening of Sex Chromosome Aneuploidy

AIMS

In this study, we examined the doses of the stature homeobox (SHOX), vesicle-associated membrane protein 7 (VAMP7), and SRY genes to establish a protocol for using peripheral blood samples deposited on filter paper for the screening of sex chromosome aneuploidy in neonates. We also measured correlations with karyotypes to assess this method as a neonatal screening strategy.

MATERIALS AND METHODS

This was an observational, descriptive, comparative blind study. Thirty-two healthy young adults (17 women, 15 men; age, ≥18 years), four patients with known sex chromosome aneuploidy (positive control group), and 1000 healthy newborns were included. Gene dosages were determined using quantitative real-time polymerase chain reaction (RT-PCR). Values with standard deviations (SDs) of three or more were considered abnormal.

RESULTS

Men and women differed in the gene dosage of the SRY gene. Cases with Turner syndrome showed values below 3 SDs for SHOX and VAMP7 genes, and cases with Klinefelter syndrome showed values above 3 SDs for SHOX and VAMP7 genes. Two suspected cases of sex chromosome aneuploidy were diagnosed using our neonatal screening strategy; these cases were confirmed as Turner syndrome and 47,XYY syndrome by karyotyping.

CONCLUSIONS

Our data establish a basis for the determination of chromosomal sex and neonatal screening of sex chromosome aneuploidy using RT-PCR.

Evaluating genomic DNA extraction methods from human whole blood using endpoint and real-time PCR assays

The extraction of genomic DNA is the crucial first step in large-scale epidemiological studies. Though there are many popular DNA isolation methods from human whole blood, only a few reports have compared their efficiencies using both end-point and real-time PCR assays. Genomic DNA was extracted from coronary artery disease patients using solution-based conventional protocols such as the phenol-chloroform/proteinase-K method and a non-phenolic non-enzymatic Rapid-Method, which were evaluated and compared vis-a-vis a commercially available silica column-based Blood DNA isolation kit. The appropriate method for efficiently extracting relatively pure DNA was assessed based on the total DNA yield, concentration, purity ratios (A₂₆₀/A₂₈₀ and A₂₆₀/A₂₃₀), spectral profile and agarose gel electrophoresis analysis. The quality of the isolated DNA was further analysed for PCR inhibition using a murine specific ATP1A3 qPCR assay and mtDNA/Y-chromosome ratio determination assay. The suitability of the extracted DNA for downstream applications such as end-point SNP genotyping, was tested using PCR-RFLP analysis of the AGTR1-1166A>C variant, a mirSNP having pharmacogenetic relevance in cardiovascular diseases. Compared to the traditional phenol-chloroform/proteinase-K method, our results indicated the Rapid-Method to be a more suitable protocol for genomic DNA extraction from human whole blood in terms of DNA quantity, quality, safety, processing time and cost. The Rapid-Method, which is based on a simple salting-out procedure, is not only safe and cost-effective, but also has the added advantage of being scaled up to process variable sample volumes, thus enabling it to be applied in large-scale epidemiological studies.

Single Lysis-Salting Out Method of Genomic DNA Extraction From Dried Blood Spots

BACKGROUND

Dried blood spots (DBS) are an important form of bio-sampling and valuable approach for storing blood samples for genetic studies. This has necessitated in developing an effective protocol to isolate genomic DNA (gDNA) from DBS samples.In this study, we have elucidated a dependable and non-hazardous "single lysis-salting out" (SLSO) protocol of gDNA extraction from DBS and compared against the available commercial kits.

METHODS

For the purpose of this study, blood spots were collected on S&S 903 filter cards from 10 healthy volunteers and 30 patients with glutaric aciduria type I (GA-I). The gDNA was extracted from theseDBS samples by SLSO, QIAamp® gDNA Micro kit and innuPREP forensic kit methods. The quantity and quality of gDNA obtained from these methods were determined by measuring the absorbance using a Nanodrop spectrophotometer.

RESULTS

The SLSO method showed four-fold and eight-fold increased yield of gDNA in healthy volunteers and patient samples, respectively, compared to commercial kits (p<0.0001). The protocol was also found to be cost efficient, reducing the per sample cost to almost half. The suitability of this method for genetic studies was confirmed by performing R402W genotyping by RFLP in GA-I patients. The genotyping results showed the presence of R402W mutation in 20% (6/30) of patients.

CONCLUSION

The SLSO method was found to be inexpensive, non-hazardous and a suitable technique for isolating gDNA from DBS samples for genetic studies.

Evaluation of artemether-lumefantrine efficacy in the treatment of uncomplicated malaria and its association with pfmdr1, pfatpase6 and K13-propeller polymorphisms in Luanda, Angola

Background

Drug resistance in Plasmodiumfalciparum has posed an obstacle to effective treatment and challenges many malaria control programmes in endemic areas. In Angola, until 2003, chloroquine (CQ) was used as first-line therapy for uncomplicated malaria. It was replaced initially by amodiaquine and, in 2006, by artemisinin-based combination therapy (ACT) with artemether-lumefantrine (AL, Coartem^®). Efficacy study of ACT, conducted in Angola between 2004 and 2005, showed a baseline efficacy of ≈99 %.

Methods

103 malaria patients were enrolled according to WHO proceedings. Patients were followed up with clinical and parasitological evaluations for 28 days, parasite density and identification was evaluated by microscopy, the pfmsp2 were genotyped by nested-PCR, to distinguish parasite recrudescence from new infections; the polymorphisms at codons 86 and 1246 of pfmdr1 gene, and 769 of pfatp6 gene were assessed by PCR–RFLP and sequencing for pfk13-propeller genotype.

Results

The cure rate was 91.3 %. The obtained results showed that from 103 patients, 12.6 % (n = 13) still had parasitaemia 1 day after the treatment was finished. On day 0, of the 94 evaluated samples, wild-type alleles were identified in 73.4 % (n = 69) for pfmdr1 N86Y position and only one sample carried the mutant allele (Y) for pfmdr1 1246; 14 % of these samples showed increased pfmdr1 copy number; 100 % (n = 21) had wild-type allele of k13 gene in all the studied positions.

Discussion

These results showed changes in parasite profile susceptibility to AL in comparison to the baseline data from 2002 to 2004 and on the genotyping characteristics; the clinical outcome after treatment with AL did not link a particular genotype with treatment failure; observed changes do not provide sufficient evidence for a treatment policy change, but they suggest that a carefully monitoring is needed in this area.