Search

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.

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.

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.

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.

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.

Background: Hepatitis B virus (HBV) is a small DNA-containing virus with 4 genes, C, S, X and P. The S gene codes for the surface antigen (HBsAg), which contains the "a" determinant, the main region for induction of a protective humoral immune response. To compare the genotype and sequence of the "a" determinant between strains isolated from asymptomatic and symptomatic Mexican HBV carriers., Results: 21 asymptomatic (blood donors) and 12 symptomatic (with clinical signs and with >1 year lamivudine treatment) HBV carriers were studied; all patients were positive for the HBsAg in serum. Viral load, genotypes, and subtypes were determined in plasma. A fragment of the S gene including the "a" determinant was PCR amplified and sequenced to determine genotype, subtype and to identify mutations. Mean viral load was 0.7965 x 104 copies/ml in asymptomatic carriers and 2.73 x 106 copies/ml in symptomatic patients. Genotypes H, C, and F were identified in asymptomatic individuals; whereas H was dominant in symptomatic patients. A fragment of 279 bp containing the "a" determinant was amplified from all 33 carriers and sequences aligned with S gene sequences in the GenBank. Mutations identified were Y100N, T126I, Q129H and N146K in the asymptomatic group, and F93I and A128V in the symptomatic group., Conclusion: Differences in genotype and in mutations in the "a" determinant were found between strains from asymptomatic and symptomatic HBV Mexican carriers.

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.

The response to 2 consecutive protease inhibitor (P1) combination regimens was evaluated in a cohort of HIV-1-infected children. Twelve children, most of whom had been heavily treated, received a 3-drug treatment: saquinavir in hard gelatin capsules (SQVhgc) + zidovudine (ZDV) + didanosine. When this treatment failed it was replaced by a 4-drug regimen: ritonavir + SQVhgc + ZDV + lamivudine. A mild and temporary decrease in viral load (VL) was observed with the initial regimen (p = 0.22). Therapy failure occurred in 7 patients (58%) within 9 months and in another 3 (25%) within 9-18 months. The 7 children who failed within 9 months received the subsequent boosted regimen, leading to a significant and lasting reduction in VL (p = 0.001). None of the patients failed on the boosted regimen: 5/7 achieved a VL of < 400 copies/ml and 3/7 achieved a VL of < 50 copies/ml. Our results suggest that a 4-drug regimen including 2 PIs produces a better and more sustained response than a 3-drug regimen including only 1 PI, and that a good, sustained response is possible with subsequent boosted regimens even in heavily treated children.

Background: Non-A, non-B virus is responsible for 75-90% of all cases of blood transfusion-related hepatitis. The aim of this work was to determine hepatitis C virus RNA (HCV-RNA) in a group of blood donors and their household contacts. Serotype and genotype of the isolates were also studied., Methods: HCV antibodies were investigated in 44,588 blood donors with a commercial immunoassay. Forty-four seropositive donors and 72 household members were further studied. Quantitative analysis of viral RNA was performed with Amplicor HCV 2.0 test, while genotype was determined by INNO-LiPA test and serotype with Murex HCV test., Results: Among the 44,588 donors studied, 333 (0.74%) were positive for anti-HCV. Viral RNA was found in 35 (80%) of the 44 seropositive cases studied. Among the 72 household members, HCV antibodies were detected in six (8.3%) and HCV-RNA in four of these individuals. Serotype 1 and genotype 1 were the most frequent types detected (48 and 64%, respectively). The genotype in the blood donor matched that of his seropositive family member in four of six cases., Conclusions: Our results suggest that intrafamilial transmission of HCV may occur and we stress the need to study household members of seropositive blood donors, as they have a high risk of infection. In this community, genotype 1 is the most prevalent type in blood donors and family members.

Background: There is no information on the use of live varicella vaccine in Mexican children. Our objective was to evaluate antibody response and safety of the live varicella vaccine in both healthy and immunocompromised Mexican children., Methods: One hundred children with no history of varicella/zoster were vaccinated with a live attenuated varicella vaccine. According to their immune status, patients were divided into either a compromised (leukemia, solid tumors, chronic renal failure, and cirrhosis) or a healthy children group. Serum IgG antibodies against VZV were measured by ELISA at baseline and at 3 and 6 months after vaccination., Results: A positive VZV-ELISA at baseline was detected in 36 of 67 (53.7%) immunocompromised children and in 22 of 33 (66%) healthy children. Among VZV-seronegative children, seroconversion at 6 months post-vaccination was observed in 90.3% of compromised children and in 100% of healthy children. Increases in serum antibody levels at 3 and 6 months post-vaccination was similar in both groups. VZV vaccine-related adverse reactions, mostly mild and local, were detected in 29% of the children. Three compromised children had a mild rash symptomatic of varicella after vaccination., Conclusions: About 50% of immunosuppressed children (mean age 8.8 +/- 3.6 years) with no varicella history were VZV-seronegative. Almost all of these compromised VZV-seronegative patients seroconverted 6 months after vaccine. In addition, antibody titers were similar in both compromised and healthy children.

Background: Hepatitis E virus (HEV) infection causes an acute, self-limited hepatitis associated with high mortality in pregnant women. Community-based surveys are scarce and information on HEV infection in populations is needed. The aim of this work was to study seroprevalence to HEV in young adults and children in Mexico, using a community-based survey., Methods: Serum samples from 3,549 individuals were studied; the population included subjects from 1 to 29 years old from all regions of the country representing all socioeconomic levels. IgG anti-HEV was determined by ELISA., Results: Anti-HEV antibodies were found in 374 (10.5%) individuals. Seroprevalence increased with age from 1.1% in children younger than 5 years to 14.2% in persons 26 to 29 years of age (p = 0.006). Risk factors for infection included living in rural communities and a low educational level. Seroprevalence was not associated with the level of regional development., Conclusions: HEV infection is endemic in Mexico. Age, type of community, and educational level were identified as risk factors for infection.

Pregnant women infected with hepatitis B and C viruses pose a risk for infecting their newborn infants by vertical transmission. We studied 6,253 pregnant women aged 12-49 years for infection with hepatitis B (HBV) and C (HCV) viruses. Infection was diagnosed by measuring IgG antibodies against HBc, HBs, HBe, as well as IgM-HBc and HCV viral antigens with commercially available immunoassay kits. HBV infection was detected in 113 cases (1.8%), and prevalence was significantly higher (2.4%) in a group of women with a high-risk pregnancy who were attending a perinatology hospital than in healthy pregnant women (1.67%, p < 0.05). Infection with HBV was significantly higher in women older than 30 years old (p < 0.05). HBsAg was found in blood, colostrum and vaginal exudate of two pregnant women; HBsAg was detected in the gastric aspirate but not in the blood of the two newborn infants. HBeAg and IgM-HBc were not detected in any of the samples. DNA-HBV was detected in serum of seven women, and DNA-HBV was detected in the gastric aspirate of only one of the newborns. HCV infection was diagnosed in three out of 111 women with markers for HBV infection (2.7%), and in 6 out of 1,000 women without these markers (0.6%). Anti-HCV antibodies were found in the serum of six of their infants during up to six months of age. Infants were monitored for one year and none of them developed any sign of hepatic disease. These results suggest that special attention should be paid to women older than 30 years and with a high-risk pregnancy, as they are at a higher risk of HBV and HCV infections.

In this work we compare the sensitivity, specificity and predictive values of hemagglutination inhibition (HI), immunofluorescent assay (IFA), biotin-streptavidin immunofluorescent assay (B/SA-IFA), enzyme-linked immunosorbent assay (EIA) and plaque neutralization test (PN). This study includes serum samples from children taken before and after vaccination, children with clinically diagnosed measles and household contacts. EIA were the most specific and better serological diagnostic test. HI and IFA had high sensitivity but low specificity. An alternative to EIA is B/SAIFA, which is cheaper than EIA and can be used in the study of small outbreaks or in isolated cases.

The aim of this study was to determine the prevalence of specific antibodies against rubella virus in pregnant women from Iztapalapa and Nezahualcóyotl areas of the valley of Mexico, in order to evaluate susceptibility to this virus in these areas. Serum samples collected from 5535 women between 15 and 44 years old were studied by the hemaglutination inhibition test. 92.6% of positivity was obtained and no significant difference was observed between different age groups. The prevalence of rubella antibodies in pregnant women was 92.4% for Iztapalapa zone and 92.8% for Nezahualcóyotl. The titles of antibodies against rubella virus more frecuently presented were 1:16 (36.3%) and 1:32 (29.6%). The data obtained in this study suggest that women attending Medical Services of the Mexican Institute of Social Segurity in reproductive age from the Iztapalapa and Nezahualcóyotl areas, do not need massive vaccination against rubella virus.

Hepatitis B (HVB) is a worldwide spread health problem. It has been assessed that there are more than 300 millions of carriers. HVB has a special concern for health care workers (HCW's) due to the high risk among them of getting the infection in clinic-setting areas. According to some estimation, the risk for hepatitis B among HCW's is 2 to 10 times higher than the risk for general population. The risk is related to the degree of direct contact with blood and body fluids, as well as, with the frequency of traumatic exposure in the work place. The control of this infection is based on the observance of universal precautions and the vaccination, since there is not treatment against this disease. The results of an efficacy-evaluation of DNA recombinant vaccine against hepatitis B are reported; 174 HCW's were studied; three dosages of vaccine were administered (0.1st and 6th month) by I.M. via. In addition, three serum samples were collected at 0, 1st and 9th month after vaccine administration. We did not find carriers of surface antigen of hepatitis B. With regards to seroconverted individuals we observed the following results: there were a satisfactory response to the vaccine in 163 individuals (93.7%); however, 8 (4.6%) persons did not reach titles of protective antibodies and 3 (1.7%) did not show seroconversion at all. Therefore, 11 persons (6.3% of the total) did not result immunized. The secondary reactions to the vaccines were low in frequency and mainly of local presentation. Among the study population we did not find chronic carries of hepatitis B.(ABSTRACT TRUNCATED AT 250 WORDS)

41 volunteer blood donors and his relatives were studied in order to know about the prevalence of hepatitis B and D virus infections in selected groups. Frequency of HBsAg+ carriers was 0.34 per cent in the Centro Nacional de la Transfusión Sanguínea and 0.15 per cent in the Banco Central de Sangre, IMSS. Most of the HBsAg+ blood donors were 21 to 40 years old (87.8%); 21.9 per cent had IgM antibodies against HBc and just 2.4 per cent were HBeAg positive. Forty one (26.9%) of 152 relatives had one or more of the HBV markers, 3.9 per cent were HBsAg carriers and 1.3 per cent were HBeAg positive. In the infected relatives group 36.6 per cent were ancestory or brothers and just 14.6 per cent of wives were infected. None of the HBsAg+ blood donors or his relatives had antibodies against delta agent. These results support the fact that the frequency of asymptomatic carriers of HBsAg in the volunteer blood donors group is similar to he frequency in the general population and identifies the group of relatives as those with the highest risk to acquire HBV infection.