Development and Evaluation of a Set of Spike and Receptor Binding Domain-Based Enzyme-Linked Immunosorbent Assays for SARS-CoV-2 Serological Testing.

The implementation and validation of anti-SARS-CoV-2 IgG serological assays are reported in this paper. S1 and RBD proteins were used to coat ELISA plates, and several secondary antibodies served as reporters. The assays were initially validated with 50 RT-PCR positive COVID-19 sera, which showed high IgG titers of mainly IgG1 isotype, followed by IgG3. Low or no IgG2 and IgG4 titers were detected. Then, the RBD/IgG assay was further validated with 887 serum samples from RT-PCR positive COVID-19 individuals collected at different times, including 7, 14, 21, and 40 days after the onset of symptoms. Most of the sera were IgG positive at day 40, with seroconversion happening after 14-21 days. A third party conducted an additional performance test of the RBD/IgG assay with 406 sera, including 149 RT-PCR positive COVID-19 samples, 229 RT-PCR negative COVID-19 individuals, and 28 sera from individuals with other viral infections not related to SARS-CoV-2. The sensitivity of the assay was 99.33%, with a specificity of 97.82%. All the sera collected from individuals with infectious diseases other than COVID-19 were negative. Given the robustness of this RBD/IgG assay, it received approval from the sanitary authority in Mexico (COFEPRIS) for production and commercialization under the name UDISTEST-V2G®.

Dengue Virus Coinfection in Human Immunodeficiency Virus-1-Infected Patients on the West Coast of Mexico.

Dengue virus infection in human immunodeficiency virus (HIV)-positive patients is not well studied. Previous reports suggest a transitory inhibition of the HIV-1 viral load, as well as a benign clinical progression of dengue. The follow-up of six HIV-1-infected patients, diagnosed and hospitalized with dengue virus infection in the State of Colima, Mexico, was carried out to analyze the progression of this viral coinfection. The presence of dengue virus serotype 1 was confirmed through molecular tests. No severe complications were observed in any of the patients during dengue virus infection. Significant alteration of the HIV-1 viral loads was not observed during dengue virus infection and 6 months after coinfection. Further studies are required to understand the pathology, as well as the clinical course, of these viral coinfections.

Complete Genome Sequence of Hepatitis B Virus Genotype E, the First Molecular Characterization from an Imported Case in Mexico.

Hepatitis B virus infection is currently a global public health problem. Here, we present the first characterization and complete genome sequence of a strain belonging to genotype E in Mexico, obtained from a foreign carrier with chronic infection.

[Twelve years of experience in the diagnosis of syphilis in Mexico. Period 2001-2012]. / Doce años de experiencia en el diagnóstico de sífilis en México (periodo 2001-2012).

OBJECTIVE: To determine the incidence of syphilis in Mexico in patients suspected of having the disease or any risk factor. MATERIALS AND METHODS: We performed a descriptive, longitudinal, randomized design study from the period of January 2001 to December 2012, where 51,302 samples were analyzed for syphilis in risk groups. RESULTS: A 39.73% frequency of positive cases was calculated. The estimated average age of detection was 29.08 years. It was found that syphilis affects 47.05% of males and 52.85% of females. The most affected states were Chiapas, Tabasco, and Hidalgo. CONCLUSIONS: Syphilis, despite its decrease in frequency, is an important disease in the major risk groups, so it is vital to take preventive measures to reduce the occurrence of new cases and eliminate cases of congenital syphilis.

Infectious diseases in Mexico. A survey from 1995-2000.

Data obtained at a central laboratory for emerging, re-emerging, and other infectious diseases in Mexico from 1995-2000 are presented. An outstanding increase of DEN-3 circulation was identified. Aedes aegypti, the dengue vector, is widely distributed. Leptospirosis has become the most important differential diagnosis for dengue. Identification of rabies virus variants allowed cataloging of new transmitters of rabies. Rotavirus showed a clear seasonal distribution, while different proportions of pathogenic classes of Escherichia coli under endemic and outbreak conditions were seen. Serotypes of several bacteria are reported as well as the sources of isolation and frequency of Shigella, Salmonella, and Vibrio cholerae. Rise and disappearance of cholera could be followed along the past decade. Influenza strains were identified, as were several pathogens causing sexually transmitted infections. Laboratory support was important for surveillance after Hurricane Mitch. Multidrug-resistant strains of Mycobacterium tuberculosis are emerging and primary resistance is very high. It is now mandatory to search for antibodies to Trypanosoma cruzi in blood banks. Triatoma barberi, a peridomestic bug, is the main vector of Chagas disease. Localized cutaneous leishmaniosis increased in regions having a guerrilla element in Chiapas. Modern immunodiagnostic techniques are used for control studies of cysticercosis and similar techniques were recently standardized for Trichinella spiralis detection. Low iodine values in children's urine were found in several Mexican states; therefore, use of iodized salt should be encouraged.

Cuantificación de linfocitos T CD4+ y de RNA viral en pacientes con VIH/SIDA / Quantification of CD4+ T lymphocytes and viral DNA in patients with HIV/AIDS

Se determinaron los valores de los marcadores de progresión (carga viral y cuenta de linfocitos T CD4+) de 410 pacientes que viven con VIH-SIDA, que estaban en diferentes etapas clínicas de la enfermedad y bajo diferentes esquemas terapéuticos. El objetivo fue determinar la correlación entre los valores de los marcadores de progresión y el estado clínico de los pacientes. Se utilizaron metodologías comerciales para cuantificar las subpoblaciones de linfocitos y el RNA viral circulante. Los resultados indican que existía correlación entre los valores de CD4+ bajos y la carga viral alta en pacientes que estaban bajo tratamiento antirretroviral pero no en pacientes sin tratamiento. Además el análisis de 1208 muestras procesadas durante 1999 mostró que el 46 por ciento de los pacientes tenían menos de 200 linfocitos T CD4+/mL de sangre y más de 500 copias de RNA circulante. Se discuten las implicaciones de estos resultados en la salud pública de México.