Impact of core protein naturally selected mutants associated with HBeAg-negative status in HBV biosynthesis.

Hepatitis B e antigen (HBeAg) loss represents a late stage of chronic hepatitis B virus (HBV) infection associated with a drastic decrease in HBV-DNA, a lower risk of disease progression, and the occurrence of several mutations in the preCore/core region. However, the underlying mechanisms supporting the downregulation of viral replication have yet to be elucidated. In the present study, the analysis of the frequency of subgenotype D1 core protein (HBc) mutations associated with HBeAg status revealed a higher mutation rate in HBeAg-negative sequences compared to HBeAg-positive ones. Particularly, 22 amino acids exhibited a higher frequency of mutation in HBeAg-negative sequences, while the remaining residues showed a high degree of conservation. Subsequently, the assessment of HBc mutants derived from HBeAg-negative patients in viral structure and replicative capacity revealed that HBc mutations have the ability to modulate the subcellular localization of the protein (either when the protein was expressed alone or in the context of viral replication), capsid assembly, and, depending on specific mutation patterns, alter covalently closed circular DNA (cccDNA) recycling and up- or downregulate viral replication. In conclusion, HBc mutations associated with HBeAg-negative status impact on various stages of the HBV life cycle modulating viral replication during the HBeAg-negative stage of infection.

NOVEL POXVIRAL INFECTION IN THREE FINCH SPECIES ILLEGALLY IMPORTED INTO TRINIDAD, WEST INDIES, WITH IMPLICATIONS FOR NATIVE BIRDS.

Oryzoborus angolensis (Lesser Seed-Finch), Oryzoborus crassirostris (Large-billed Seed-Finch), and Sporophila intermedia (Grey Seedeater) are finch species native to the Caribbean island of Trinidad. These species are locally trapped and kept for their song, but with declining native populations, enthusiasts have turned to illegally importing birds from the South American mainland. The smuggling of wild birds from South America poses significant disease risks to the native bird species of Trinidad. Herein we describe the first case of poxviral infection in these illegally imported birds in Trinidad and partial genome sequence of the causative agent. Phylogenetic analysis of the 4b core protein sequence indicated that the avian poxvirus identified was most closely related to a 2012 avian pox sequence from Brazil, with 96.2% and 98.1% identity at the nucleotide and amino acid level.

Osteonecrosis of the femoral head in people living with HIV: anatomopathological description and p24 antigen test.

OBJECTIVE: To examine the presence of HIV in bone tissue of people living with HIV (PLWHIV) with osteonecrosis of femoral head and describe clinical and anatomopathological findings. DESIGN: This is a case series which included 44 PLWHIV with osteonecrosis of femoral head who underwent total hip arthroplasty. METHODS: Clinical data were obtained through analysis of the patients' medical records. Bone tissue obtained during total hip arthroplasty was retrieved and sent for conventional and immunohistochemical analysis. Monoclonal antibodies were used to mark the p24 (HIV), CD31 (vascular endothelial cells), CD68 (macrophages), and D240 (cells of the lymphatic endothelium) antigens. RESULTS: Dyslipidemia was found in 48% of the patients and lipodystrophy in 31%. Histological analysis showed similar characteristics for the entire sample. Degeneration of joint cartilage was visualized with the presence of fissures and fibrillations, as well as subchondral sclerosis and necrosis of the subchondral cancellous bone tissue. Lymphoplasmocytic inflammatory reaction was observed, with the presence of macrophages containing a foamy, vacuolated cytoplasm, as well as the presence of ceroid pigment and occasional granulation tissue. The reaction with the monoclonal anti-p24 antibody was negative in the samples from all 44 PLWHIV undergoing hip arthroplasty. Reactions with the anti-CD31 and anti-D240 antibodies were negative. Staining with CD68 antibody confirmed that the cells visualized with foamy, vacuolated cytoplasm were macrophages. CONCLUSION: p24 HIV antigen was not detected in the bone tissue of PLWHIV and osteonecrosis. The most frequent anatomopathological findings were extensive necrosis of bone tissue, large vacuoles filled with fat cells, inflammatory lymphoplasmocytic reaction with macrophages containing vacuolated cytoplasm, and the presence of ceroid pigment.

Charge neutralization as the major factor for the assembly of nucleocapsid-like particles from C-terminal truncated hepatitis C virus core protein.

BACKGROUND: Hepatitis C virus (HCV) core protein, in addition to its structural role to form the nucleocapsid assembly, plays a critical role in HCV pathogenesis by interfering in several cellular processes, including microRNA and mRNA homeostasis. The C-terminal truncated HCV core protein (C124) is intrinsically unstructured in solution and is able to interact with unspecific nucleic acids, in the micromolar range, and to assemble into nucleocapsid-like particles (NLPs) in vitro. The specificity and propensity of C124 to the assembly and its implications on HCV pathogenesis are not well understood. METHODS: Spectroscopic techniques, transmission electron microscopy and calorimetry were used to better understand the propensity of C124 to fold or to multimerize into NLPs when subjected to different conditions or in the presence of unspecific nucleic acids of equivalent size to cellular microRNAs. RESULTS: The structural analysis indicated that C124 has low propensity to self-folding. On the other hand, for the first time, we show that C124, in the absence of nucleic acids, multimerizes into empty NLPs when subjected to a pH close to its isoelectric point (pH ≈ 12), indicating that assembly is mainly driven by charge neutralization. Isothermal calorimetry data showed that the assembly of NLPs promoted by nucleic acids is enthalpy driven. Additionally, data obtained from fluorescence correlation spectroscopy show that C124, in nanomolar range, was able to interact and to sequester a large number of short unspecific nucleic acids into NLPs. DISCUSSION: Together, our data showed that the charge neutralization is the major factor for the nucleocapsid-like particles assembly from C-terminal truncated HCV core protein. This finding suggests that HCV core protein may physically interact with unspecific cellular polyanions, which may correspond to microRNAs and mRNAs in a host cell infected by HCV, triggering their confinement into infectious particles.

Detección de anticuerpos contra la proteína de 24 kd del VIH-1: Correlación clínico serológica

Se estudió la presencia de anticuerpos contra la proteína de 24 kd del VIH mediante el empleo paralelo del Western Blot DAVIH BLOT y del DAVIH AC P24 en muestras de suero de 176 pacientes en diferentes estadíos de la infección por VIH-1. Los resultados se correlacionaron con la clasificación clínica del paciente al momento de la toma de muestra y con la evolución posterior durante 6 meses. El 57 % de los pacientes con infecciones oportunistas menores y el 96 % de los enfermos de SIDA presentaron títulos bajos de anticuerpos. Los fallecidos no mostraron reactividad o presentaron títulos muy bajos en muestras tomadas antes del fallecimiento. Se observaron diferentes titulaciones en grupos de sueros con reactividad aparentemente uniforme en el Western Blot. Los resultados indican una adecuada correlaciòn clínico serológica; por lo que el ELISA DAVIH AC P24 pudiera ser útil en el seguimiento clínico de personas infectadas por el VIH-1.

The presence of antibodies against the HIV protein of 24 kd was studies by the parallel use of the DAVIH BLOT Western Blot and of the DAVIH AC P24 ELISA in serum samples from 176 patients at different HIV-1 infection stages. The results were correlated with the clinical classification of the patient at the moment of taking the sample and with the further evolution during 6 months. 57 % of the patients with opportunistic minor infections and 96 % of AIDS patients had low antibodies titres. Dead pattients showed no reactivity or presented very low titres in samples taken before dying. Different titrations were observed in serum groups with an apparently uniform reactivity in the Western Blot. The results show and adequate clinical and serological correlation. Therefore, the DAVIH AC P24 ELISA could be useful in the clinical follow-up of HIV-1 infected persons.