Dried Serum Samples for Antibody Detection in Arthropod-Borne Virus Infections Are an Effective Alternative to Serum Samples.

The disease burden of arthropod-borne infections is particularly high in low- and middle-income countries, where the availability of resources for surveillance and testing is limited. The lack of local infrastructure demands that biological samples be sent to central laboratories by refrigerated transport, which increases costs and the risk of sample degradation. Dried blood spot samples are an alternative for ensuring sample integrity during transportation and storage. They can be used for the detection of nucleic acids and proteins, such as antigens or antibodies. Here, we compared anti-chikungunya IgM, anti-dengue IgM, anti-dengue IgG, and anti-Zika IgG detection between paired serum and dried serum samples (DSSs); the agreement between results was found to be 90.6%, 94.1%, 85.9%, and 95.5%, respectively, indicating a strong correlation. Our results suggest that DSSs provide a reliable alternative for detection of specific antibodies in arthropod-borne infections.

Cervicovaginal and rectal colonization by group B Streptococci in Mexican women with full-term pregnancies.

BACKGROUND: A pregnant woman rectally or vaginally colonized by group B Streptococcus can infect her newborn. PATIENTS AND METHODS: Prospective, cross-sectional, analytical 24-month study in pregnant women. Women in labor with ≥ 36 weeks of gestation were included. Pregnancy was classified as normal or high-risk. Main risk factors of the pregnant women were analyzed. Rectal and vaginal samples were obtained, placed in Todd-Hewitt broth and subsequently inoculated in 5% sheep blood agar. Identification was carried out by biochemical tests and latex agglutination. RESULTS: 3,347 pregnant women were included. Mean age was 25.6 ± 5.3 years, 95.5% received antenatal care; 2,213 (66%) had normal-risk pregnancies, and in 1,370 (41%), delivery was by cesarean section. Overall colonization was 4.3% (145/3,347), and it was higher in the 30-34 years age group (6.8%). Serotype I (58%) was the most common. CONCLUSION: The percentage of colonization in this population was low. A routine cervicovaginal and rectal culture program in pregnant women and the intrapartum antimicrobial prophylaxis program are controversial in our region.

ANTECEDENTES: Una mujer embarazada colonizada por estreptococo del grupo B por vía rectal o vaginal puede infectar a su recién nacido. PACIENTES Y MÉTODOS: Estudio prospectivo, transversal y analítico, durante 24 meses, en embarazadas. Se incluyeron aquellas en trabajo de parto con ≥ 36 semanas de gestación. El embarazo se clasificó como normal o de alto riesgo. Se analizaron los principales factores de riesgo de las embarazadas. Se tomaron muestras rectales y vaginales, se colocaron en caldo Todd-Hewitt y posteriormente se inocularon en agar sangre de carnero al 5%. La identificación se realizó mediante pruebas bioquímicas y aglutinación con látex. RESULTADOS: Se incluyeron 3,347 embarazadas, edad media 25.6 ± 5.3 años, 95.5% con control prenatal; 2,213 (66%) embarazo de riesgo normal y 1,370 (41%) obtenidas por cesárea. La colonización global fue del 4.3% (145/3,347), siendo mayor en el grupo de edad de 30 a 34 años (6.8%). El serotipo I (58%) fue el más frecuente. CONCLUSIÓN: El porcentaje de colonización en esta población fue bajo. Un programa sistemático de cultivo cervicovaginal y rectal en mujeres embarazadas y el programa de profilaxis antimicrobiana intraparto son controvertidos en nuestra región.

Identification of mutations in the S gene of hepatitis B virus in HIV positive Mexican patients with occult hepatitis B virus infection.

INTRODUCTION AND AIM: Occult hepatitis B virus infection (OBI) is characterized by the presence of replication-competent hepatitis B virus (HBV) DNA in the liver and/or serum of patients with undetectable levels of the HBV surface antigen (HBsAg). Due to the shared infection routes HIV positive patients are at higher risk of developing OBI, thus, the aim of this study was to determine the frequency of OBI in Mexican HIV-infected patients and to identify mutations in the HBV S gene that could be associated to the development of OBI. MATERIALS AND METHODS: Plasma samples from 50 HIV-infected patients with undetectable levels of the HBsAg were obtained and analyzed. The Core, PreS and S genes were amplified by nested PCR and sequenced by the Sanger method. To analyze HBV diversity in the OBI-positive patients, ten sequences of 762bp from the HBV S gene were selected, cloned, and subsequently sequenced for mutational analyses. RESULTS: OBI infection was found with a frequency of 36% (18/50). All the HBV sequences corresponded to the H genotype. The most common mutations were: C19Y, Q129H, E164D, and I195M, with a frequency of 44%, 36%, 39% and 48% respectively. CONCLUSIONS: In this study, we report the presence of OBI in a cohort of Mexican HIV-infected patients with an overall prevalence of 36%. Mutational analyses revealed that four non-silent mutations were frequent in different regions of the HBsAg gene, suggesting that they might be associated to the development of OBI in this population, nevertheless, further studies are required to determine their role in the pathogenesis of OBI.

Serum Dried Samples to Detect Dengue Antibodies: A Field Study.

BACKGROUND: Dried blood and serum samples are useful resources for detecting antiviral antibodies. The conditions for elution of the sample need to be optimized for each disease. Dengue is a widespread disease in Mexico which requires continuous surveillance. In this study, we standardized and validated a protocol for the specific detection of dengue antibodies from dried serum spots (DSSs). METHODS: Paired serum and DSS samples from 66 suspected cases of dengue were collected in a clinic in Veracruz, Mexico. Samples were sent to our laboratory, where the conditions for optimal elution of DSSs were established. The presence of anti-dengue antibodies was determined in the paired samples. RESULTS: DSS elution conditions were standardized as follows: 1 h at 4°C in 200 µl of DNase-, RNase-, and protease-free PBS (1x). The optimal volume of DSS eluate to be used in the IgG assay was 40 µl. Sensitivity of 94%, specificity of 93.3%, and kappa concordance of 0.87 were obtained when comparing the antidengue reactivity between DSSs and serum samples. CONCLUSION: DSS samples are useful for detecting anti-dengue IgG antibodies in the field.

[Cytomegalovirus: congenital infection and clinical presentation in infants with respiratory distress syndrome]. / Citomegalovirus: infección congénita y presentacion clínica en recién nacidos con síndrome de dificultad respiratoria.

BACKGROUND: Respiratory distress syndrome (RDS) is a multifactorial and common disease that varies from 15 to 50 % in the newborn, causing 50 % of mortality. The RDS may be associated with bacterial and viral infections, and one of the most common viral agents is the cytomegalovirus (CMV). In the neonatal period the virus incidence goes from 0.4 to 2.5 % with a seroprevalence of 50 to 75 %; the incidence of infection in newborn with RDS is unknown. The objective was to determine the frequency of CMV infection in neonates with RDS and identify the risk factors associated with infection. METHODS: The CMV-DNA was identified in plasma by quantitative PCR; maternal and neonatal variables that defined the clinical findings were analyzed by logistic regression.The CMV-DNA was identified in plasma by quantitative PCR; maternal and neonatal variables that defined the clinical findings were analyzed by logistic regression. RESULTS: The frequency of CMV infection in 197 infants with RDS was 8.6 % (95 % CI, 4.7-12.5). The significant variables in newborn were: neutropenia (p = 0.012), thrombocytopenia (p = 0.021), mottled skin (p = 0.03), and the maternal significant variable was cervicovaginitis (p = 0.05). CONCLUSIONS: We reported for the first time the highest frecuency of CMV infection in newborns with RDS and the association of various risk factors with CMV infection.

Introducción: el síndrome de dificultad respiratoria (SDR) es una enfermedad común multifactorial que varía del 15 al 50 % en el recién nacido (RN), y la mortalidad es de 50 %. Puede estar asociado a infecciones bacterianas y virales, una de las más frecuentes: el citomegalovirus (CMV). En el periodo neonatal la incidencia de infección por CMV es de 0.4 a 2.5 % y la seroprevalencia de 50 a 75 %; se desconoce la incidencia de infección en los RN. El objetivo fue determinar la frecuencia de infección por CMV en recién nacidos con SDR e identificar factores de riesgo asociados a infección. Métodos: el DNA-CMV fue identificado en plasma por reacción en cadena de la polimerasa (PCR) cuantitativa, y las variables maternas y neonatales que definieron el cuadro clínico fueron analizadas por regresión logística. Resultados: la frecuencia de infección por CMV en 197 RN con SDR fue de 8.6 % (IC 95 % 4.7-12.5). Las variables significativas en los RN fueron: neutropenia (p = 0.012), trombocitopenia (p = 0.021), piel marmórea (p = 0.03) y la variable materna significativa fue cervicovaginitis (p = 0.05). Conclusiones: se reporta por primera vez la frecuencia más alta de infección por CMV en RN con SDR y la asociación de varios factores de riesgo con la infección por CMV.

Occult hepatitis B virus co-infection in human immunodeficiency virus-positive patients: A review of prevalence, diagnosis and clinical significance.

The prevalence of human immunodeficiency virus (HIV) and hepatitis B virus (HBV) co-infection is high as they share similar mechanisms of transmission. The development and widespread use of highly sensitive tests for HBV diagnosis has demonstrated that a significant proportion of apparently healthy individuals with evidence of exposure to HBV continue to carry fully functional HBV DNA in their hepatocytes, a situation that predisposes them to the development of progressive liver disease and hepatocellular carcinoma. The presence of co-infections frequently influences the natural evolution of each of the participating infections present by either facilitating their virulence or competing for resources. Furthermore, the drugs used to treat these infections may also contribute to changes in the natural course of these infections, making the analysis of the impact of co-infection more difficult. The majority of studies has examined the impact of HIV on overt chronic hepatitis B, finding that co-infection carries an increased risk of progressive liver disease and the development of hepatocellular carcinoma. Although the effect of HIV on the natural history of occult hepatitis B infection (OBI) has not been fully assessed, all available data suggest a persisting risk of repeated flares of hepatitis and progressive liver disease. We describe studies regarding the diagnosis, prevalence and clinical significance of OBI in HIV-positive patients in this short review. Discrepancies in worldwide prevalence show the urgent need for the standardization of diagnostic criteria, as established by the Taormina statements. Ideally, standardized protocols for testing should be employed to enable the comparison of data from different groups. Additional studies are needed to define the differences in risk for OBI without HIV and in HIV-HBV co-infected patients with or without overt disease.

Use of Dried Plasma Spots for HIV-1 Viral Load Determination and Drug Resistance Genotyping in Mexican Patients.

Monitoring antiretroviral therapy using measurements of viral load (VL) and the genotyping of resistance mutations is not routinely performed in low- to middle-income countries because of the high costs of the commercial assays that are used. The analysis of dried plasma spot (DPS) samples on filter paper may represent an alternative for resource-limited settings. Therefore, we evaluated the usefulness of analyzing DPS samples to determine VL and identify drug resistance mutations (DRM) in a group of HIV-1 patients. The VL was measured from 22 paired plasma and DPS samples. In these samples, the average VL was 4.7 log10 copies/mL in liquid plasma and 4.1 log10 copies/mL in DPS, with a correlation coefficient of R = 0.83. A 1.1 kb fragment of HIV pol could be amplified in 14/22 (63.6%) of the DPS samples and the same value was amplified in plasma samples. A collection of ten paired DPS and liquid plasma samples was evaluated for the presence of DRM; an excellent correlation was found in the identification of DRM between the paired samples. All HIV-1 pol sequences that were obtained corresponded to HIV subtype B. The analysis of DPS samples offers an attractive alternative for monitoring ARV therapy in resource-limited settings.

Occult hepatitis B virus infection among Mexican human immunodeficiency virus-1-infected patients.

AIM: To determine the frequency of occult hepatitis B infection (OHBI) in a group of human immunodeficiency virus (HIV)-1+/ hepatitis B surface antigen negative (HBsAg)- patients from Mexico. METHODS: We investigated the presence of OHBI in 49 HIV-1+/HBsAg- patients. Hepatitis B virus (HBV) DNA was analyzed using nested PCR to amplify the Core (C) region and by real-time PCR to amplify a region of the S and X genes. The possible associations between the variables and OHBI were investigated using Pearson's χ(2) and/or Fisher's exact test. RESULTS: We found that the frequency of OHBI was 49% among the group of 49 HIV-1+/HBsAg- patients studied. The presence of OHBI was significantly associated with the HIV-1 RNA viral load [odds ratio (OR) = 8.75; P = 0.001; 95%CI: 2.26-33.79] and with HIV-antiretroviral treatment with drugs that interfere with HBV replication (lamivudine, tenofovir or emtricitabine) (OR = 0.25; P = 0.05; 95%CI: 0.08-1.05). CONCLUSION: The OHBI frequency is high among 49 Mexican HIV-1+/HBsAg- patients and it was more frequent in patients with detectable HIV RNA, and less frequent in patients who are undergoing HIV-ARV treatment with drugs active against HBV.

Genotypic testing for HIV-1 drug resistance using dried blood samples.

In third-world countries, dried blood samples (DBS) are a convenient alternative to plasma for monitoring viral load during HIV-1 therapy. In this study, we evaluated the feasibility of using DBS to perform HIV-1 drug resistance genotyping in a ViroSeq assay in which the protease and reverse transcriptase regions of the pol gene are analyzed. Fifty-seven antiretroviral genotypes from plasma samples were tested, and drug resistance genotypes were determined. Only 38.6% paired DBS samples were sequenced. Failure to amplify DNA from DBS samples generally correlated with plasma viral loads below log(10) 5.1. The majority of the mutations identified in plasma pol sequences were also found in their DBS counterpart, with a concordance in genotype interpretation of 96.4%. Several factors were identified that could potentially improve both the sensitivity and the quality of genotype data, such as sample storage conditions and sequence analysis. Therefore, DBS sampling is useful to determine viral load and drug resistance genotypes in HIV patients.

Use of dried blood samples for monitoring hepatitis B virus infection.

BACKGROUND: Hepatitis B virus (HBV) infection is a problem in several regions of the world with limited resources. Blood samples dried on filter paper (DBS) have been successfully used to diagnose and monitor several infectious diseases. In Mexico there is an urgent need for an affordable and easy sampling method for viral load (VL) testing and monitoring of chronic HBV infection. The purpose of this work was to validate the utility of DBS samples for monitoring HBV infection in patients from Mexico City. METHODS: Matched samples of plasma and DBS on filter paper from 47 HBV infected patients from the Instituto Mexicano del Seguro Social (IMSS), were included. To evaluate the DNA stability and purity from DBS stored at different temperature conditions, samples from ten patients were stored at 4 degree, 25 degree, and 37 degree C for 7 days. After DBS elution and DNA extraction, the purity of these samples was determined measuring the O.D. rate 260/280. The DBS utility for molecular studies was assessed with PCR assays to amplify a 322 bp fragment from the "a" determinant region of the HBV "S" gene. The VL from all samples was determined to evaluate the correlation between plasma and DBS matched samples. RESULTS: The quality of the DNA from DBS specimen is not adversely affected by storage at 4 degree, 25 degree and 37 degree C for up 7 days. Statistical ANOVA analyses did not show any significant difference. The same amplification efficiency was observed between DNA templates from samples stored at different temperatures. The Pearson correlation between the VL from DBS and plasma matched samples was 0.93 (p = 0.01). The SD was 1.48 for DBS vs.1.32 for Plasma, and an average of log10 copies/mL of 5.32 vs. 5.53. ANOVA analysis did not show any statistically significant difference between the analyzed groups (p = 0.92). CONCLUSION: The results provide strong evidence that the isolation and quantification of DNA-HBV from DBS is a viable alternative for patient monitoring, and molecular characterization of the virus variants circulating in Mexico.

High correlation of human immunodeficiency virus type-1 viral load measured in dried-blood spot samples and in plasma under different storage conditions.

BACKGROUND: To measure HIV-1 RNA concentration requires venous extraction of blood, use of RNAase-free materials, and transport in a cold chain, which makes difficult the management of samples in developing countries. We evaluated the utility of the determination of HIV-1 RNA concentration in blood samples dried on filter paper (DBS) and subjected to different conditions, as contrasted with determination in plasma. METHODS: HIV-1 RNA concentration was determined in HIV-infected patients in DBS and in plasma samples. Samples were subjected to the following: DBS were stored at 4, 22, and 37 degrees C for 1, 3, and 7 days; samples from patients from four regions of Mexico were mailed to a reference laboratory; DBS were sent under environmental conditions; and plasma samples were sent frozen. HIV-1 RNA concentrations were determined by NucliSens in DBS and by Amplicor test in plasma. RESULTS: HIV-1 RNA concentration determined in DBS subjected to different temperatures and times had a significant correlation (r=0.99) with those obtained in plasma. When compared with values in plasma, Kappa agreement coefficients of values in DBS stored for 7 days at 4, 22, and 37 degrees C were 0.98, 0.83, and 0.94, respectively. Quantification of HIV-1 RNA in 108 DBS mailed from remote areas with different climates demonstrated significant correlation with those obtained in plasma (r=0.95; p <0.001). CONCLUSIONS: DBS is a simple and reliable method to measure HIV-1 RNA concentration, especially when samples are mailed from remote areas to a reference center. This collection method is an economic and suitable alternative for use in developing countries.