Conjugated Bilirubin Differentially Regulates CD4+ T Effector Cells and T Regulatory Cell Function through Outside-In and Inside-Out Mechanisms: The Effects of HAV Cell Surface Receptor and Intracellular Signaling.

We recently reported an immune-modulatory role of conjugated bilirubin (CB) in hepatitis A virus (HAV) infection. During this infection the immune response relies on CD4+ T lymphocytes (TLs) and it may be affected by the interaction of HAV with its cellular receptor (HAVCR1/TIM-1) on T cell surface. How CB might affect T cell function during HAV infection remains to be elucidated. Herein, in vitro stimulation of CD4+ TLs from healthy donors with CB resulted in a decrease in the degree of intracellular tyrosine phosphorylation and an increase in the activity of T regulatory cells (Tregs) expressing HAVCR1/TIM-1. A comparison between CD4+ TLs from healthy donors and HAV-infected patients revealed changes in the TCR signaling pathway relative to changes in CB levels. The proportion of CD4+CD25+ TLs increased in patients with low CB serum levels and an increase in the percentage of Tregs expressing HAVCR1/TIM-1 was found in HAV-infected patients relative to controls. A low frequency of 157insMTTTVP insertion in the viral receptor gene HAVCR1/TIM-1 was found in patients and controls. Our data revealed that, during HAV infection, CB differentially regulates CD4+ TLs and Tregs functions by modulating intracellular pathways and by inducing changes in the proportion of Tregs expressing HAVCR1/TIM-1.

T-helper 17-related cytokines and IgE antibodies during hepatitis A virus infection in children.

We determined the serum IgE levels and T-helper (Th)17-related cytokines during distinct hepatitis A virus (HAV)-induced clinical courses in children. A significantly higher concentration of macrophage inflammatory protein 3α, interleukin (IL)-17E and IL-17F in HAV-infected children with intermediate liver injury compared with those with minor liver damage was found. A reduction in the IgE levels in those patients who showed the highest levels of IL-17F in the group of intermediate liver injury was found. The data suggested that the Th17-related profile is associated with the severity of HAV infection and might play a role on the modulation achieved by HAV during allergies.

Origin of New Lineages by Recombination and Mutation in Avian Infectious Bronchitis Virus from South America.

The gammacoronavirus avian infectious bronchitis virus (IBV) is a highly contagious respiratory pathogen of primary economic importance to the global poultry industry. Two IBV lineages (GI-11 and GI-16) have been widely circulating for decades in South America. GI-11 is endemic to South America, and the GI-16 is globally distributed. We obtained full-length IBV genomes from Argentine and Uruguayan farms using Illumina sequencing. Genomes of the GI-11 and GI-16 lineages from Argentina and Uruguay differ in part of the spike coding region. The remaining genome regions are similar to the Chinese and Italian strains of the GI-16 lineage that emerged in Asia or Europe in the 1970s. Our findings support that the indigenous GI-11 strains recombine extensively with the invasive GI-16 strains. During the recombination process, GI-11 acquired most of the sequences of the GI-16, retaining the original S1 sequence. GI-11 strains with recombinant genomes are circulating forms that underwent further local evolution. The current IBV scenario in South America includes the GI-16 lineage, recombinant GI-11 strains sharing high similarity with GI-16 outside S1, and Brazilian GI-11 strains with a divergent genomic background. There is also sporadic recombinant in the GI-11 and GI-16 lineages among vaccine and field strains. Our findings exemplified the ability of IBV to generate emergent lineage by using the S gene in different genomic backgrounds. This unique example of recombinational microevolution underscores the genomic plasticity of IBV in South America.

Multiple cytokine expression profiles reveal immune-based differences in occult hepatitis B genotype H-infected Mexican Nahua patients.

A high prevalence of occult hepatitis B (OHB) genotype H infections has been observed in the native Mexican Nahua population. In addition, a low incidence of hepatitis B virus (HBV)-associated hepatocellular carcinoma has been described in Mexico. The immune response to infection among OHB-infected patients has been poorly evaluated in vivo. Therefore, we assessed the expression profiles of 23 cytokines in OHB genotype H-infected Nahua patients. A total of 41 sera samples from natives of the Nahua community were retrospectively analysed. Based on their HBV antibody profiles, patients were stratified into two groups: OHB patients (n = 21) and patients that had recovered from HBV infection (n = 20). Herein, we report distinctive cytokines profiles in OHB-infected individuals. Compared to healthy controls (n = 20) and patients who resolved HBV infection, OHB-infected patients displayed an increase in interleukin (IL)-2 secretion in addition to a characteristic inflammation profile (decrease in IL-8 and tumour necrosis factor-alpha levels and increased levels of tumour growth factor-beta). IL-15 and interferon-gamma levels were reduced in OHB-infected individuals when compared to those patients who resolved HBV infection. In contrast, OHB patients showed an increase in monocyte chemoattractant protein (MCP)-1 and MCP-2 compared to healthy controls and patients who resolved HBV infection. These findings suggest that cytokine expression can influence the severity of OHB disease and could lead to new investigation into the treatment of liver and other infectious diseases.

Hepatitis E virus: An ancient hidden enemy in Latin America.

Hepatitis E virus (HEV) infection is a common cause of acute clinical hepatitis worldwide. HEV is an RNA-containing virus and the only member of the genus Hepevirus in the family Hepeviridae. Human HEV is classified into four genotypes widely distributed across the world. The virus is mainly transmitted via the fecal-oral route, and water-borne epidemics have become characteristic of hepatitis E in developing countries, including those in Latin America. The zoonotic potential of HEV is broadly recognized. Thus, there is an urgent need to re-evaluate virus transmission scenarios and to enforce epidemiological surveillance systems. Additionally, it is known that HEV infections, initially defined as self-limiting, can also take chronic courses in immunocompromised patients. Moreover, we recently reported a high seroprevalence of HEV in samples from cirrhotic patients with no other etiological agents present, suggesting the potential role of HEV in the development of chronic liver illness. In this review, HEV genomic variability, transmission, chronic infectious course, zoonotic potential and treatment are discussed. Focus is placed on the impact of HEV infection in Latin America, to support the development of specific control strategies and the handling of this important and typically imperceptible viral infection.

Rethinking the immune properties of bilirubin in viral hepatitis: from bench to bedside.

Communication between the immune system and metabolic components can be exemplified by the process of heme catabolism. The immunomodulatory functions of the enzymes, substrates and active products related to catabolism of the heme group have been extensively studied. Bilirubin (BR), the final breakdown product of heme, is primarily considered to be a toxic waste product but has recently been considered to be an immunomodulatory metabolite. Through mechanisms that include intracellular signaling and transcriptional control, BR affects those immune cell functions that regulate cell proliferation, differentiation and apoptosis. During the pathogenesis of viral hepatitis, the heme degradation pathway is disrupted, resulting in changes to normal BR concentrations. These alterations have been previously studied mainly as a consequence of the infection. However, little is known about the potential immunomodulatory role played by BR in the development of infectious hepatocellular diseases. Differences in BR levels in the context of viral hepatitis are likely to provide important insights into the metabolite-mediated mechanisms controlling the immune responses underlying both the long-term persistence of hepatitis C virus (HCV) infection and the resolution of hepatitis A virus (HAV) infection during the acute phase. In this review, the cross-talk between heme catabolism and immune function is described in detail. Special emphasis is given to discoveries that hold promise for identifying immunologic features of metabolic products in the resolution of viral diseases.

Cytokine expression profiles associated with distinct clinical courses in hepatitis A virus-infected children.

We determined the serum cytokine profiles during distinct hepatitis A virus-induced clinical courses in children. A significant overexpression of interleukin-1, interleukin-6, tumor necrosis factor-alpha and monocyte chemotactic protein-2 was found in children with intermediate liver injury, whereas the patients with minor liver injury had a significant increase of interleukin-8 and transforming growth factor-beta values.

Rotaviruses require basolateral molecules for efficient infection of polarized MDCKII cells.

In this work we evaluated the ability of rotavirus strains with different receptor requirements to infect the apical and basolateral surfaces of polarized MDCKII cells. We used neuraminidase (NA)-sensitive (RRV and TFR-1) and neuraminidase-resistant (Wa and UK) viruses that differ in their use of integrins. Regardless of their receptor requirements, all virus strains tested were found to efficiently infect cells from both membrane surface domains, with preference for the basolateral domain, since: (i) disruption of tight junctions of polarized cell monolayers by calcium chelation led to a reversible increase of rotavirus infectivity, (ii) the viruses infected preferentially the cells located at the borders of microcolonies of polarized cells, and (iii) in cells grown on a permeable support all four virus strains were able to start the infection by either plasma membrane domain. Preferential infection (5-11-fold more efficiently) of the basolateral surface correlated with the neuraminidase resistance of the virus strains, but not with their requirement for integrins, which in MDCKII cells seem to be used by all four viruses. The infection of both cell surface domains by RRV was found to depend on the presence of terminal sialic acids, since its infectivity was reduced by neuraminidase treatment of the cells and it was also blocked by incubation of the virus with glycophorin A. The efficient infection through the basolateral membrane surface of polarized cells might be relevant for the pathogenesis of rotavirus, especially given the recent reports of antigenemia and extraintestinal spread of the virus in children and animal models.

Multiple cytokine expression profiles reveal immune-based differences in occult hepatitis B genotype H-infected Mexican Nahua patients

A high prevalence of occult hepatitis B (OHB) genotype H infections has been observed in the native Mexican Nahua population. In addition, a low incidence of hepatitis B virus (HBV)-associated hepatocellular carcinoma has been described in Mexico. The immune response to infection among OHB-infected patients has been poorly evaluated in vivo. Therefore, we assessed the expression profiles of 23 cytokines in OHB genotype H-infected Nahua patients. A total of 41 sera samples from natives of the Nahua community were retrospectively analysed. Based on their HBV antibody profiles, patients were stratified into two groups: OHB patients (n = 21) and patients that had recovered from HBV infection (n = 20). Herein, we report distinctive cytokines profiles in OHB-infected individuals. Compared to healthy controls (n = 20) and patients who resolved HBV infection, OHB-infected patients displayed an increase in interleukin (IL)-2 secretion in addition to a characteristic inflammation profile (decrease in IL-8 and tumour necrosis factor-alpha levels and increased levels of tumour growth factor-beta). IL-15 and interferon-gamma levels were reduced in OHB-infected individuals when compared to those patients who resolved HBV infection. In contrast, OHB patients showed an increase in monocyte chemoattractant protein (MCP)-1 and MCP-2 compared to healthy controls and patients who resolved HBV infection. These findings suggest that cytokine expression can influence the severity of OHB disease and could lead to new investigation into the treatment of liver and other infectious diseases.

Rotavirus RRV associates with lipid membrane microdomains during cell entry.

Rotavirus cell entry is a multistep process, not completely understood, which requires at least four interactions between the virus and cell surface molecules. In this work, we investigated the role of the sphingolipid- and cholesterol-enriched lipid microdomains (rafts) in the entry of rotavirus strain RRV to MA104 cells. We found that ganglioside GM1, integrin subunits alpha2 and beta3, and the heat shock cognate protein 70 (hsc70), all of which have been implicated as rotavirus receptors, are associated with TX-100 and Lubrol WX detergent-resistant membranes (DRMs). Integrin subunits alpha2 and beta3 were found to be particularly enriched in DRMs resistant to lysis by Lubrol WX. When purified RRV particles were incubated with cells at 4 degrees C, about 10% of the total infectious virus was found associated with DRMs, and the DRM-associated virus increased to 37% in Lubrol-resistant membrane domains after 60-min incubation at 37 degrees C. The virus was excluded from DRMs if the cells were treated with methyl-beta-cyclodextrin (MbetaCD). Immunoblot analysis of the viral proteins showed that the virus surface proteins became enriched in DRMs upon incubation at 37 degrees C, being almost exclusively localized in Lubrol-resistant DRMs after 60 min. These data suggest that detergent-resistant membrane domains play an important role in the cell entry of rotaviruses, which could provide a platform to facilitate the efficient interaction of the rotavirus receptors with the virus particle.