Hantavirus cardiopulmonary syndrome (HCPS) is a highly pathogenic emerging disease (40% case fatality rate) caused by New World hantaviruses. Hantavirus infections are transmitted to humans mainly by inhalation of virus-contaminated aerosol particles of rodent excreta and secretions. At present, there are no antiviral drugs or immunotherapeutic agents available for the treatment of hantaviral infection, and the survival rates for infected patients hinge largely on early virus recognition and hospital admission and aggressive pulmonary and hemodynamic support. In this study, we show that Andes virus (ANDV) interacts with human apolipoprotein H (ApoH) and that ApoH-coated magnetic beads or ApoH-coated enzyme-linked immunosorbent assay plates can be used to capture and concentrate the virus from complex biological mixtures, such as serum and urine, allowing it to be detected by both immunological and molecular approaches. In addition, we report that ANDV-antigens and infectious virus are shed in urine of HCPS patients.

Diamine Oxidase (DAO) has an essential role for degradation of exogenous histamine in the intestine; thus, histamine intolerance (HI) mainly has been correlated to a low concentration and/or activity of this enzyme. The objective of the study was to standardize a colorimetric technique to measure the enzymatic activity (function) of hDAO to then apply it to a series of 22 patients with a clinical diagnosis of HI. For the standardization variables such as volume and type of sample, incubation time, wavelength of maximum absorption, types of substrates, and concentration of oxidized ascorbate were evaluated. Then the activity and concentration of DAO was determined in 22 patients diagnosed with HI and 22 healthy subjects. The mean of serum DAO concentration in the 22 patients was of 9.268 ± 1.124 U/mL. The mean of serum DAO concentration in the 22 controls was of 20.710 ± 2.509 U/mL, being significantly higher (P value 0.0002) the mean of the samples. The mean of serum DAO activity of the patients was of 1.143 ± 0.085 U/L and the controls was 1.533 ± 0.119 U/L, significantly greater than the patients (P value 0.011). In addition, the sensitivity of both techniques was 0.63. In the measuring of DAO concentration the specificity was 0.9, constituting a good diagnostic test, especially to rule out the true negatives. The determination of DAO activity had a specificity of 0.68. Although we used a small number of patients and controls and the absorbance values were lower than expected, statistically significant differences were found in the levels of concentration and DAO activity between the patients with histamine intolerance and the controls. Therefore, the measuring of DAO concentration and DAO activity is a good diagnostic strategy for study suspect cases of HI. The simultaneous use of both assays allows to reduce positive and negative false results, for example, patients with normal DAO levels that could present a dysfunction in the activity of this enzyme.

Dengue virus was detected for the first time in Chile, in an outbreak of dengue fever on Easter Island. The virus was isolated in tissue culture and characterized by reverse transcription-polymerase chain reaction as being dengue type 1.

We have used the expression library immunization technology to study the protection of Coho salmon Oncorhynchus kisutch to the infection with Piscirickettsia salmonis. Purified DNA from this bacterium was sonicated and the fragments were cloned in the expression vector pCMV-Bios. Two libraries were obtained containing 22,000 and 28,000 colonies and corresponding to approximately 8 and 10 times the genome of the pathogen, respectively. On average, the size of the inserts ranged between 300 and 1,000 bp. The plasmid DNA isolated from one of these libraries was purified and 20 micrograms were injected intramuscularly into 60 fish followed by a second dose of 10 micrograms applied 40 days later. As control, fish were injected with the same amount of DNA of the vector pCMV-Bios without insert. The titer of IgM anti-P. salmonis of vaccinated fish, evaluated 60 days post-injection, was significantly higher than that of the control group injected with the vector alone. Moreover, this response was specific against P. salmonis antigens, since no cross reaction was detected with Renibacterium salmoninarum and Yersinia ruckeri. The vaccinated and control fish were challenged 60 days after the second dose of DNA with 2.5 x 10(7) P. salmonis corresponding to 7.5 times the LD50. At 30 days post-challenge, 100% mortality was obtained with the control fish while 20% of the vaccinated animals survived. All surviving fish exhibited a lower bacterial load in the kidney than control fish. The expression library was also tested in Balb/c mice and it was found that the humoral immune response was specific to P. salmonis and it was dependent on the amount of DNA injected.

Integrase strand transfer inhibitors (INSTIs) are widely used in HIV treatment, yet few large-scale studies have examined acquired resistance (AR) at the population level. This study assessed the prevalence, patterns, and clinical implications of AR to INSTIs in Chile over a 12-year period. We analyzed 5266 genotypic sequences from ART-experienced individuals with confirmed virological failure and INSTI-based regimens between 2012 and 2023. Resistance-associated mutations were classified using the Stanford HIVdb algorithm. Resistance trends were compared between pre-pandemic (2012-2019) and post-pandemic (2020-2023) periods. High AR rates were observed for first-generation INSTIs: raltegravir (28 %) and elvitegravir (27.7 %). Lower resistance levels were found for dolutegravir (8.3 %), bictegravir (8.3 %), and cabotegravir (18.7 %). Major resistance mutations included N155H (25.2 %), Q148 H/K/R (17.2 %), and Y143R (14.3 %). Notably, Q148 H/K/R mutations were always found in combination with other major mutations. Subtype-specific differences were observed, with higher first-generation INSTI resistance in subtype F (55.6 %) than in subtype B (23.9 %). Post-pandemic resistance increased significantly for first-generation INSTIs (25 % vs. 31 %, p < 0.05). The mutation N155H, while not impacting DTG or BIC significantly, conferred intermediate resistance to CAB. CAB resistance was detected despite its absence in treatment protocols, likely due to cross-resistance pathways. Acquired INSTIs resistance in Chile is high, especially for first-generation drugs. These findings highlight the need for nationwide molecular surveillance and pre-treatment genotyping, particularly before initiating long-acting regimens such as CAB-LA. Strategic monitoring will be critical to maintaining the efficacy of current and next-generation INSTIs.