Utility of the dried blood on filter paper as a source of cytokine mRNA for the analysis of immunoreactions in Plasmodium yoelii infection

Impact of congenital cytomegalovirus infection on transcriptomes from archived dried blood spots in relation to long-term clinical outcome

Congenital Cytomegalovirus infection (cCMV) is the leading infection in determining permanent long-term impairments (LTI), and its pathogenesis is largely unknown due to the complex interplay between viral, maternal, placental, and child factors. The cellular activity, considered to be the result of the response to exogenous and endogenous factors, is captured by the determination of gene expression profiles. In this study, we determined whole blood transcriptomes in relation to cCMV, CMV viral load and LTI development at 6 years of age by using RNA isolated from neonatal dried blood spots (DBS) stored at room temperature for 8 years. As DBS were assumed to mainly reflect the neonatal immune system, particular attention was given to the immune pathways using the global test. Additionally, differential expression of individual genes was performed using the voom/limma function packages. We demonstrated feasibility of RNA sequencing from archived neonatal DBS of children with cCMV, and non-infected controls, in relation to LTI and CMV viral load. Despite the lack of statistical power to detect individual genes differences, pathway analysis suggested the involvement of innate immune response with higher CMV viral loads, and of anti-inflammatory markers in infected children that did not develop LTI. Finally, the T cell exhaustion observed in infected neonates, in particular with higher viral load, did not correlate with LTI, therefore other mechanisms are likely to be involved in the long-term immune dysfunction. Despite these data demonstrate limitation in determining prognostic markers for LTI by means of transcriptome analysis, this exploratory study represents a first step in unraveling the pathogenesis of cCMV, and the aforementioned pathways certainly merit further evaluation.

Dried Blood Spot RNA Transcriptomes Correlate with Transcriptomes Derived from Whole Blood RNA

Obtaining RNA from clinical samples collected in resource-limited settings can be costly and challenging. The goals of this study were to 1) optimize messenger RNA extraction from dried blood spots (DBS) and 2) determine how transcriptomes generated from DBS RNA compared with RNA isolated from blood collected in Tempus tubes. We studied paired samples collected from eight adults in rural Tanzania. Venous blood was collected on Whatman 903 Protein Saver cards and in tubes with RNA preservation solution. Our optimal DBS RNA extraction used 8 × 3-mm DBS punches as the starting material, bead beater disruption at maximum speed for 60 seconds, extraction with Illustra RNAspin Mini RNA Isolation kit, and purification with Zymo RNA Concentrator kit. Spearman correlations of normalized gene counts in DBS versus whole blood ranged from 0.887 to 0.941. Bland-Altman plots did not show a trend toward over- or under-counting at any gene size. We report a method to obtain sufficient RNA from DBS to generate a transcriptome. The DBS transcriptome gene counts correlated well with whole blood transcriptome gene counts. Dried blood spots for transcriptome studies could be an option when field conditions preclude appropriate collection, storage, or transport of whole blood for RNA studies.

Plasmodium knowlesi and human malaria parasites in Khan Phu, Vietnam: Gametocyte production in humans and frequent co-infection of mosquitoes

Four species of malaria parasite, Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium knowlesi infect humans living in the Khanh Phu commune, Khanh Hoa Province, Vietnam. The latter species also infects wild macaque monkeys in this region. In order to understand the transmission dynamics of the three species, we attempted to detect gametocytes of the three species in the blood of infected individuals, and sporozoites in the salivary glands of mosquitoes from the same region. For the detection of gametocyte-specific mRNA, we targeted region 3 of pfg377, pvs25, pmg and pks25 as indicators of the presence of P. falciparum, P. vivax, P. malariae and P. knowlesi gametocytes, respectively. Gametocyte-specific mRNA was present in 37, 61, 0 and 47% of people infected with P. falciparum (n = 95), P. vivax (n = 69), P. malariae (n = 6) or P. knowlesi (n = 32), respectively. We found that 70% of mosquitoes that had P. knowlesi in their salivary glands also carried human malaria parasites, suggesting that mosquitoes are infected with P. knowlesi from human infections.

Psychological resilience and the gene regulatory impact of posttraumatic stress in Nepali child soldiers

Adverse social conditions in early life have been linked to increased expression of proinflammatory genes and reduced expression of antiviral genes in circulating immune cells-the conserved transcriptional response to adversity (CTRA). However, it remains unclear whether such effects are specific to the Western, educated, industrialized, rich, and democratic (WEIRD) cultural environments in which previous research has been conducted. To assess the roles of early adversity and individual psychological resilience in immune system gene regulation within a non-WEIRD population, we evaluated CTRA gene-expression profiles in 254 former child soldiers and matched noncombatant civilians 5 y after the People's War in Nepal. CTRA gene expression was up-regulated in former child soldiers. These effects were linked to the degree of experienced trauma and associated distress-that is, posttraumatic stress disorder (PTSD) severity-more than to child soldier status per se. Self-perceived psychological resilience was associated with marked buffering of CTRA activation such that PTSD-affected former child soldiers with high levels of personal resilience showed molecular profiles comparable to those of PTSD-free civilians. These results suggest that CTRA responses to early life adversity are not restricted to WEIRD cultural contexts and they underscore the key role of resilience in determining the molecular impact of adverse environments.

High specificity of semi-nested multiplex PCR using dried blood spots on DNA Banking Card in comparison with frozen liquid blood for detection of Plasmodium falciparum and Plasmodium vivax

BACKGROUND

Venipuncture sampling in test tubes for detecting malaria parasites using PCR assays possesses a number of limitations such as reluctance of patients, some difficulties in transportation of blood samples and freezing them for long time. To overcome the mentioned limitations, some approaches have been employed by a number of authors. This study was proposed to compare between DNA Banking Card (DBC) filter papers containing dried finger-prick blood and venipunctured frozen liquid blood.

METHODS

A total of 75 specimens was prepared from the equal enrolled individuals using three blood storage approaches; making Geimsa-stained thin and thick smears from each individual to determine the malaria-positive or -negative specimens, spotting two to three drops of finger-prick blood onto the DBC filter paper, and collecting a 2-ml venous blood sample into EDTA-contained test tube from each individual. A semi-nested Multiplex PCR technique with DNA extracted from the two latter sets of specimens was used for plasmodia diagnosis.

RESULTS

DNA samples isolated from dried blood spotted on the DBC filter papers resulted in 32 (42.7%) positive and 43 (57.3%) negative cases comparable with the results outcome of frozen liquid blood with 35 (46.7%) positive and 40 (53.3%) negative cases. Statistical analysis revealed higher sensitivity for SnM-PCR using DNA from liquid blood with 100% vs. dried blood spotted on DBC with 97% but higher specificity for the DBC with 100% vs. liquid blood with 95.2%.

CONCLUSIONS

Based on the results obtained from this study to overcome the problems of venipuncture frozen liquid blood sampling, replacement of a reliable filter paper for preserving finger-prick blood samples is a trustable and useful facilitator particularly in remote malaria-endemic areas.

Anopheles dirus co-infection with human and monkey malaria parasites in Vietnam

The feasibility of identifying parasite DNA and specific mRNAs from wild-caught Anopheles dirus mosquitoes was assessed using dried mosquito salivary glands preserved on filter paper. We were able to detect Plasmodium falciparum, Plasmodium vivax, Plasmodium malariae and Plasmodium knowlesi DNA by conventional PCR and, furthermore, detected P. falciparum gametocyte-specific genes, pfg377 and pfs16 mRNA, P. knowlesi circumsporozoite protein (CSP) and sporozoite surface protein 2 (SSP2) mRNA by reverse transcription-PCR. Using this technique, we were able to confirm the presence of P. vivax, P. falciparum and P. knowlesi in one particular wild-caught mosquito. These results indicate that P. knowlesi may be transmitted by the primary human malaria vector in forested areas in Vietnam. This study also shows that the preservation of mosquito salivary glands on filter paper, and the down-stream extraction of parasite DNA and RNA from those, offers a powerful resource for molecular epidemiological studies on malaria.

Archived unfrozen neonatal blood spots are amenable to quantitative gene expression analysis

BACKGROUND

State laws in the USA mandate that blood be drawn from all newborn infants to screen for health-threatening conditions. These screening assays consume only a small portion of the blood samples, which are collected on filter paper ('Guthrie') cards. Many states archive unused blood spots, often in unrefrigerated storage.

OBJECTIVES

While individual RNA transcripts have been identified from archived neonatal blood spots, no study to date has performed quantitative analysis of archived blood spot RNA.

METHODS

We demonstrate that RNA can be isolated and amplified from newborn blood spots stored unfrozen for as long as 9 years, and can be analyzed by microarray and qPCR.

RESULTS

Microarray assays of archived neonatal blood spots consistently detected 3,000-4,000 expressed genes with correlations of 0.90 between replicates. Blood spot mRNA is amenable to qPCR and we detected biologically relevant expression levels of housekeeping and immune-mediating genes.

CONCLUSIONS

These experiments demonstrate the feasibility of using blood spots as a source of RNA which can be analyzed using quantitative microarray and qPCR assays. The application of these methods to the analysis of widely collected biological specimens may be a valuable resource for the study of perinatal determinants of disease development.

A dried blood sample on filter paper is suitable for detecting Plasmodium falciparum gametocytes by reverse transcription polymerase chain reaction

The detection of gametocytes in human peripheral blood is one of the most important measures in a malaria survey. We attempted to detect gametocytes of Plasmodium falciparum by reverse transcription polymerase chain reaction (RT-PCR) of dried blood on filter paper. On field samples analysis, the specific RT-PCR products for region 3 of pfg377 mRNA were observed in 67 of 131 falciparum malaria patients. The minimum detection level of RT-PCR-positive samples was 0.03 gametocytes/microl on quantitative real-time RT-PCR. Gametocyte positive rate was not dependent on sex or age. A higher frequency of gametocytes was found in single P. falciparum infection than in mixed species infection (P<0.01). In this study, 47 of the 131 patients were asymptomatic. Eighteen of these 47 patients showed pfg377 mRNA expression. Moreover, four alleles of region 3 of pfg377 were detected in pfg377 mRNA-positive patients and 13 of 67 pfg377 mRNA-positive patients carried more than one gametocyte-producing clone. These results suggest that dried blood on filter paper is a useful for a molecular epidemiologic study of malaria transmission and gametocyte-targeted control.

Osteopontin is involved in Th1-mediated immunity against Plasmodium falciparum infection in a holoendemic malaria region in Vietnam

We examined the role of osteopontin (OPN) in immunity against Plasmodium falciparum infection. We measured the mRNA levels for OPN and several cytokines in RNA preparations extracted from dried blood on filter paper obtained from falciparum malaria patients in Vietnam. Expression of OPN mRNA was detected in 134 of 161 patients. The expression of both interleukin-12 p40 and interferon-gamma mRNAs in the group positive for OPN mRNA was significantly higher than that in the group negative for OPN mRNA. The level of parasitemia in the OPN mRNA-positive group was much lower than that in the negative one. These results suggest that OPN might suppress multiplication of the parasites through T helper 1 cells-mediated immune responses.