HTLV-1 p12 modulates the levels of prion protein (PrPC) in CD4+ T cells.

Introduction: Infection with human T cell lymphotropic virus type 1 (HTLV-1) is endemic in Brazil and is linked with pro-inflammatory conditions including HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), a chronic neuroinflammatory incapacitating disease that culminates in loss of motor functions. The mechanisms underlying the onset and progression of HAM/TSP are incompletely understood. Previous studies have demonstrated that inflammation and infectious agents can affect the expression of cellular prion protein (PrPC) in immune cells. Methods: Here, we investigated whether HTLV-1 infection affected PrPC content in cell lines and primary CD4+cells in vitro using flow cytometry and western blot assays. Results: We found that HTLV-1 infection decreased the expression levels of PrPC and HTLV-1 Orf I encoded p12, an endoplasmic reticulum resident protein also known to affect post-transcriptionally cellular proteins such as MHC-class I and the IL-2 receptor. In addition, we observed a reduced percentage of CD4+ T cells from infected individuals expressing PrPC, which was reflected by IFN type II but not IL-17 expression. Discussion: These results suggested that PrPC downregulation, linked to both HTLV-1 p12 and IFN-γ expression in CD4+ cells, may play a role in the neuropathogenesis of HTLV-1 infection.

Lessons from the Cerebrospinal Fluid Analysis of HTLV-1-Infected Individuals: Biomarkers of Inflammation for HAM/TSP Development.

HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP) is a neurodegenerative disease that leads to motor impairment due to a chronic inflammatory process in the central nervous system (CNS). However, the HAM/TSP pathogenesis is not completely clear, and biomarkers to define the disease prognosis are still necessary. Thus, we aimed to identify biomarkers for HAM/TSP and potential mechanisms involved in disease development. To that end, the concentrations of VILIP-1, BDNF, VEGF, ß-NGF, TGF-ß1, fractalkine/CX3CL1, IL-6, IL-18, and TNF-α, and the soluble forms of TREM-1, TREM-2, and RAGE, were assessed using a multiplex bead-based immunoassay in paired cerebrospinal fluid (CSF) and serum samples from HAM/TSP patients (n = 20), asymptomatic HTLV-1 carriers (AC) (n = 13), and HTLV-1-seronegative individuals (n = 9), with the results analyzed according to the speed of HAM/TSP progression. HAM/TSP patients had elevated fractalkine in the serum but not in the CSF, particularly those with low neuroinflammatory activity (CSF/serum ratio of neopterin <1 and of CXCL10 < 2). HAM/TSP patients with normal CSF levels of neurofilament light chain (NfL) showed elevated ß-NGF in serum, and serum BDNF levels were increased in HTLV-1-infected individuals, particularly in HTLV-1 AC. Both HTLV-1 AC and HAM/TSP patients had lower TGF-ß1 levels in CSF compared to uninfected individuals, and HAM/TSP patients with active CNS inflammation showed higher CSF levels of IL-18, which correlated with markers of inflammation, neuronal death, and blood−brain-barrier permeability. Although none of the factors evaluated were associated with the speed of HAM/TSP progression, reduced TGF-ß1 levels in CSF suggest that suppressive responses to control subclinical and/or active neurodegeneration are impaired, while increased CSF IL-18 indicates the involvement of inflammasome-mediated mechanisms in HAM/TSP development.

Early Effects of HTLV-1 Infection on the Activation, Exhaustion, and Differentiation of T-Cells in Humanized NSG Mice.

Adult T-cell leukemia/lymphoma (ATLL) is an aggressive malignancy of CD4+ T-cells associated with HTLV-1 infection. In this study, we used the model of immunodeficient NSG mice reconstituted with a functional human immune system (HIS) to investigate early events in HTLV-1 pathogenesis. Upon infection, human T-cells rapidly increased in the blood and lymphoid tissues, particularly CD4+CD25+ T-cells. Proliferation of CD4+ T-cells in the spleen and mesenteric lymph nodes (MLN) correlated with HTLV-1 proviral load and CD25 expression. In addition, splenomegaly, a common feature of ATLL in humans, was also observed. CD4+ and CD8+ T-cells predominantly displayed an effector memory phenotype (CD45RA-CCR7-) and expressed CXCR3 and CCR5 chemokine receptors, suggesting the polarization into a Th1 phenotype. Activated CD8+ T-cells expressed granzyme B and perforin; however, the interferon-γ response by these cells was limited, possibly due to elevated PD-1 expression and increased frequency of CD4+FoxP3+ regulatory T-cells in MLN. Thus, HTLV-1-infected HIS-NSG mice reproduced several characteristics of infection in humans, and it may be helpful to investigate ATLL-related events and to perform preclinical studies. Moreover, aspects of chronic infection were already present at early stages in this experimental model. Collectively, we suggest that HTLV-1 infection modulates host immune responses to favor viral persistence.

Polymorphisms in HTLV-1 Tax-responsive elements in HTLV-1-associated myelopathy/tropical spastic paraparesis patients are associated with reduced proviral load but not with disease progression.

Human T-lymphotropic virus type 1 (HTLV-1) provirus expression is mainly directed by Tax-responsive elements (TRE) within the long terminal repeats (LTR). Mutations in TRE can reduce provirus expression and since a high proviral load (PVL) is a risk factor for the development of HTLV-1-associated myelopathy/tropical spastic paraparesis (HAM/TSP), we evaluated polymorphisms in the 5' LTR and the association with PVL and disease progression. HTLV-1 LTR and tax sequences derived from asymptomatic carriers (AC) and HAM/TSP patients followed in a longitudinal study were analysed according to PVL and clinical severity. Individuals infected with HTLV-1 presenting the canonical TRE, considering strain ATK-1 as the consensus, displayed sustained higher PVL. By contrast, an LTR A125G mutation in TRE was associated with slightly reduced PVL only in HAM/TSP patients, although it did not influence the speed of disease progression. Moreover, this polymorphism was frequent in Latin American strains of the HTLV-1 Cosmopolitan Transcontinental subtype. Therefore, polymorphisms in the 5' TRE of HTLV-1 may represent one of the factors influencing PVL in HAM/TSP patients, especially in the Latin American population. Indeed, higher PVL in the peripheral blood has been associated with an increased inflammatory activity in the spinal cord and to a poorer prognosis in HAM/TSP. However, this event was not associated with TRE polymorphisms.

ZIKA Virus Neutralizing Antibody Kinetics in Antenatally Exposed Infants.

BACKGROUND: Zika virus (ZIKV) is associated with severe congenital abnormalities and laboratory diagnosis of antenatal infection is difficult. Here we evaluated ZIKV neutralizing antibody (nAb) kinetics in infants born to mothers with PCR-confirmed ZIKV infection during pregnancy. METHODS: Neonates (n = 98) had serum specimens tested repeatedly for ZIKV nAb over the first 2 years of life using virus neutralization test (VNT). ZIKV neonatal infection was confirmed by RT-PCR in blood or urine and/or presence of ZIKV IgM antibodies, and results were correlated with infant clinical features. RESULTS: Postnatal laboratory evidence of ZIKV vertical transmission was obtained for 60.2% of children, while 32.7% exhibited clinical abnormalities. Congenital abnormalities were found in 37.3% of children with confirmed ZIKV infection and 31.0% of children without confirmed infection (P = .734). All but 1 child displayed a physiologic decline in ZIKV nAb, reflecting maternal antibody decay, despite an early ZIKV-IgM response in one-third of infants. CONCLUSIONS: Infants with antenatal ZIKV exposure do not develop ZIKV nAb despite an early IgM response. Therefore, ZIKV VNT in children is not useful for diagnosis of congenital infection. In light of these findings, it remains to be determined if children infected in utero are potentially susceptible to reinfection.

Comparison of parasite load by qPCR and histopathological changes of inner and outer edge of ulcerated cutaneous lesions of cutaneous leishmaniasis.

BACKGROUND: Cutaneous leishmaniasis (CL) is an infectious vector-borne disease caused by protozoa of the Leishmania genus that affects humans and animals. The distribution of parasites in the lesion is not uniform, and there are divergences in the literature about the choice of the better sampling site for diagnosis-inner or outer edge of the ulcerated skin lesion. In this context, determining the region of the lesion with the highest parasite density and, consequently, the appropriate site for collecting samples can define the success of the laboratory diagnosis. Hence, this study aims to comparatively evaluate the parasite load by qPCR, quantification of amastigotes forms in the direct exam, and the histopathological profile on the inner and outer edges of ulcerated CL lesions. METHODS: Samples from ulcerated skin lesions from 39 patients with confirmed CL were examined. We performed scraping of the ulcer inner edge (base) and outer edge (raised border) and lesion biopsy for imprint and histopathological examination. Slides smears were stained by Giemsa and observed in optical microscopy, the material contained on the smears was used to determine parasite load by quantitative real-time PCR (qPCR) with primers directed to the Leishmania (Viannia) minicircle kinetoplast DNA. The histopathological exam was performed to evaluate cell profile, tissue alterations and semi-quantitative assessment of amastigote forms in inner and outer edges. PRINCIPAL FINDINGS: Parasite loads were higher on the inner edge compared to the outer edge of the lesions, either by qPCR technique (P<0.001) and histopathological examination (P< 0.003). There was no significant difference in the parasite load between the imprint and scraping on the outer edge (P = 1.0000). CONCLUSION/SIGNIFICANCE: The results suggest that clinical specimens from the inner edge of the ulcerated CL lesions are the most suitable for both molecular diagnosis and direct parasitological examination.

Patients with COVID-19 and neurological manifestations show undetectable SARS-CoV-2 RNA levels in the cerebrospinal fluid.

We report that patients with COVID-19 displaying distinct neurological disorders have undetectable or extremely low levels of SARS-CoV-2 RNA in the cerebrospinal fluid, indicating that viral clearance precede the neurological involvement. This finding points to the need for the development of more sensitive molecular tests and the investigation of other neurotropic pathogens to exclude concurrent neuroinfection.

Dengue fever and human T-cell lymphotropic virus type 1 infection.

Globalization has increased both the number of emergent diseases and the diversity of co-infections, which could in turn mutually influence the pathogenesis of well-known infectious diseases. Here, we report the first series of chronic human T-cell lymphotropic virus type 1 (HTLV-1) patients co-infected with the dengue fever virus. As both of these diseases are immuno-mediated, we anticipated interference in the development of both diseases, with atypical clinical and laboratory parameter results. All the patients had classic dengue fever, and the main outstanding abnormality was leukopenia associated with lymphopenia. Although a mutual influence was expected, dengue fever did not affect the clinical course of HTLV-1 infection, and HTLV-1 proviral loads revealed unpredictable patterns of change.

Estudo de marcadores biológicos para o desenvolvimento de paraparesia espástica tropical/mielopatia associada ao HTLV-1 (PET/MAH) em indivíduos infectados pelo vírus linfotrópico para células T humanas do tipo 1 (HTLV-1) / Study of biological markers for the development of tropical spastic paraparesis / HTLV-associated myelopathy-1 (TSP / HAM) in individuals infected with human T lymphotropic virus to cell type 1 (HTLV-1)

O vírus linfotrópico para células T humanas do tipo 1 (HTLV - 1) é um retrovírus que acarreta uma infecção persistente e, enquanto a maioria dos portadores permanece assintomática, cerca de 0,5 a 5 por cento dos indivíduos infectados desenvolve a paraparesia espástica tropical/mielopatia associada ao HTLV (PET/MAH). E ste estudo teve como objetivo avaliar parâmetros da dinâmica desta infecção, tais como a carga proviral (CPV), o padrão de integração do DNA proviral e frequência de clones infectados persistentes, a expressão dos genes virais tax e HBZ e das citocinas IFN -y e IL-10, além da frequência de células T reguladoras (Tregs), como prováveis marcadores biológicos para a identificação dos indivíduos assintomáticos (ACs) com maior chance de desenvolver PET/MAH. Em comparação com indivíduos saudáveis, ACs e pacientes com PET/MAH com CPV elevada (maior que 5 por cento) apresentaram frequências elevadas de Tregs (células T CD4 positivo FoxP3 positivo). A utilização isolada de FoxP3 na caracterização das Tregs foi adota da em virtude da expressão aumentada de CD25 por células T CD4 positivo , interferindo assim com a identificação clássica das Tregs (células T CD4 positivi CD25 positivo FoxP3 positivo). A análise de CD127 confirmou este fato, pois a frequência de células T CD4 positivo CD25 positivo CD127 negativo/low FoxP3 (negativo) se mostrou aumentada nos indivíduos infectados, e se correlacionou positivamente com a CPV...

Pacientes com PET/MAH apresentaram maior frequência de populações clonais predominantes infectadas , e estes clones foram capazes de persistir ao longo do tempo, sugerindo que contribuam para os níveis mais elevados de CPV comumente observados nestes indivíduos. A expressão dos genes virais tax e HBZ em células mononucleares foi detectada em baixos níveis, e correlacion ou de modo positivo com a CPV, send o observada diferença significativa na expressão de tax ex vivo entre ACs e mielopatas. Dessa forma, a presença de grandes populações clonais infectadas, mesmo que expressando pequenas concentrações de antígenos virais, serviria como um estímulo para a intensa resposta de linfócitos T citotóxicos . Esta hipótese foi corroborada pelos altos níveis de IFN em relação à IL-10 presentes nos pacientes com PET/MAH e em ACs com CPV alta, indica ndo que a avaliação conjunta destes parâmetros poderá melhor definir os ACs com maior risco de desenvolvimento de PET/MAH...