Long-Term Humoral Immune Response against SARS-CoV-2 after Natural Infection and Subsequent Vaccination According to WHO International Binding Antibody Units (BAU/mL).

The new WHO reference standard allows for the definition of serum antibodies against various SARS-CoV-2 antigens in terms of binding antibody units (BAU/mL) and thus to compare the results of different ELISA systems. In this study, the concentration of antibodies (ABs) against both the S- and the N-protein of SARS-CoV-2 as well as serum neutralization activity were evaluated in three patients after a mild course of COVID-19. Serum samples were collected frequently during a period of over one year. Furthermore, in two individuals, the effects of an additional vaccination with a mRNA vaccine containing the S1-RBD sequence on these antibodies were examined. After natural infection, the antibodies (IgA, IgG) against the S1-protein remained elevated above the established cut-off to positivity (S-IgA 60 BAU/mL and S-IgG 50 BAU/mL, respectively) for over a year in all patients, while this was not the case for ABs against the N-protein (cut-off N-IgG 40 BAU/mL, N-IgA 256 BAU/mL). Sera from all patients retained the ability to neutralize SARS-CoV-2 for more than a year. Vaccination resulted in a rapid boost of antibodies to S1-protein but, as expected, not to the N-protein. Most likely, the wide use of the WHO reference preparation will be very useful in determining the individual immune status of patients after an infection with SARS-CoV-2 or after vaccination.

Adiponectin, Leptin, and IGF-1 Are Useful Diagnostic and Stratification Biomarkers of NAFLD.

Background: Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease where liver biopsy remains the gold standard for diagnosis. Here we aimed to evaluate the role of circulating adiponectin, leptin, and insulin-like growth factor 1 (IGF-1) levels as non-invasive NAFLD biomarkers and assess their correlation with the metabolome. Materials and Methods: Leptin, adiponectin, and IGF-1 serum levels were measured by ELISA in two independent cohorts of biopsy-proven obese NAFLD patients and healthy-liver controls (discovery: 38 NAFLD, 13 controls; validation: 194 NAFLD, 31 controls) and correlated with clinical data, histology, genetic parameters, and serum metabolomics. Results: In both cohorts, leptin increased in NAFLD vs. controls (discovery: AUROC 0.88; validation: AUROC 0.83; p < 0.0001). The leptin levels were similar between obese and non-obese healthy controls, suggesting that obesity is not a confounding factor. In the discovery cohort, adiponectin was lower in non-alcoholic steatohepatitis (NASH) vs. non-alcoholic fatty liver (AUROC 0.87; p < 0.0001). For the validation cohort, significance was attained for homozygous for PNPLA3 allele c.444C (AUROC 0.63; p < 0.05). Combining adiponectin with specific serum lipids improved the assay performance (AUROC 0.80; p < 0.0001). For the validation cohort, IGF-1 was lower with advanced fibrosis (AUROC 0.67, p < 0.05), but combination with international normalized ratio (INR) and ferritin increased the assay performance (AUROC 0.81; p < 0.01). Conclusion: Serum leptin discriminates NAFLD, and adiponectin combined with specific lipids stratifies NASH. IGF-1, INR, and ferritin distinguish advanced fibrosis.

Exploratory Data Analysis of Cell and Mitochondrial High-Fat, High-Sugar Toxicity on Human HepG2 Cells.

Non-alcoholic steatohepatitis (NASH), one of the deleterious stages of non-alcoholic fatty liver disease, remains a significant cause of liver-related morbidity and mortality worldwide. In the current work, we used an exploratory data analysis to investigate time-dependent cellular and mitochondrial effects of different supra-physiological fatty acids (FA) overload strategies, in the presence or absence of fructose (F), on human hepatoma-derived HepG2 cells. We measured intracellular neutral lipid content and reactive oxygen species (ROS) levels, mitochondrial respiration and morphology, and caspases activity and cell death. FA-treatments induced a time-dependent increase in neutral lipid content, which was paralleled by an increase in ROS. Fructose, by itself, did not increase intracellular lipid content nor aggravated the effects of palmitic acid (PA) or free fatty acids mixture (FFA), although it led to an up-expression of hepatic fructokinase. Instead, F decreased mitochondrial phospholipid content, as well as OXPHOS subunits levels. Increased lipid accumulation and ROS in FA-treatments preceded mitochondrial dysfunction, comprising altered mitochondrial membrane potential (ΔΨm) and morphology, and decreased oxygen consumption rates, especially with PA. Consequently, supra-physiological PA alone or combined with F prompted the activation of caspase pathways leading to a time-dependent decrease in cell viability. Exploratory data analysis methods support this conclusion by clearly identifying the effects of FA treatments. In fact, unsupervised learning algorithms created homogeneous and cohesive clusters, with a clear separation between PA and FFA treated samples to identify a minimal subset of critical mitochondrial markers in order to attain a feasible model to predict cell death in NAFLD or for high throughput screening of possible therapeutic agents, with particular focus in measuring mitochondrial function.

Persisting Neutralizing Activity to SARS-CoV-2 over Months in Sera of COVID-19 Patients.

The relationship between the nasopharyngeal virus load, IgA and IgG antibodies to both the S1-RBD-protein and the N-protein, as well as the neutralizing activity (NAbs) against SARS-CoV-2 in the blood of moderately afflicted COVID-19 patients, needs further longitudinal investigation. Several new serological methods to examine these parameters were developed, validated and applied in three patients of a family which underwent an ambulatory course of COVID-19 for six months. The virus load had almost completely disappeared after about four weeks. Serum IgA levels to the S1-RBD-protein and, to a lesser extent, to the N-protein, peaked about three weeks after clinical disease onset but declined soon thereafter. IgG levels rose continuously, reaching a plateau at approximately six weeks, and stayed elevated over the observation period. Virus-neutralizing activity reached a peak about 4 weeks after disease onset but dropped slowly. The longitudinal associations of virus neutralization and the serological immune response suggest immunity in patients even after a mild clinical course of COVID-19.

A Novel Marsupial Hepatitis A Virus Corroborates Complex Evolutionary Patterns Shaping the Genus Hepatovirus.

The discovery of highly diverse nonprimate hepatoviruses illuminated the evolutionary origins of hepatitis A virus (HAV) ancestors in mammals other than primates. Marsupials are ancient mammals that diverged from other Eutheria during the Jurassic. Viruses from marsupials may thus provide important insight into virus evolution. To investigate Hepatovirus macroevolutionary patterns, we sampled 112 opossums in northeastern Brazil. A novel marsupial HAV (MHAV) in the Brazilian common opossum (Didelphis aurita) was detected by nested reverse transcription-PCR (RT-PCR). MHAV concentration in the liver was high, at 2.5 × 109 RNA copies/g, and at least 300-fold higher than those in other solid organs, suggesting hepatotropism. Hepatovirus seroprevalence in D. aurita was 26.6% as determined using an enzyme-linked immunosorbent assay (ELISA). Endpoint titers in confirmatory immunofluorescence assays were high, and marsupial antibodies colocalized with anti-HAV control sera, suggesting specificity of serological detection and considerable antigenic relatedness between HAV and MHAV. MHAV showed all genomic hallmarks defining hepatoviruses, including late-domain motifs likely involved in quasi-envelope acquisition, a predicted C-terminal pX extension of VP1, strong avoidance of CpG dinucleotides, and a type 3 internal ribosomal entry site. Translated polyprotein gene sequence distances of at least 23.7% from other hepatoviruses suggested that MHAV represents a novel Hepatovirus species. Conserved predicted cleavage sites suggested similarities in polyprotein processing between HAV and MHAV. MHAV was nested within rodent hepatoviruses in phylogenetic reconstructions, suggesting an ancestral hepatovirus host switch from rodents into marsupials. Cophylogenetic reconciliations of host and hepatovirus phylogenies confirmed that host-independent macroevolutionary patterns shaped the phylogenetic relationships of extant hepatoviruses. Although marsupials are synanthropic and consumed as wild game in Brazil, HAV community protective immunity may limit the zoonotic potential of MHAV.IMPORTANCE Hepatitis A virus (HAV) is a ubiquitous cause of acute hepatitis in humans. Recent findings revealed the evolutionary origins of HAV and the genus Hepatovirus defined by HAV in mammals other than primates in general and in small mammals in particular. The factors shaping the genealogy of extant hepatoviruses are unclear. We sampled marsupials, one of the most ancient mammalian lineages, and identified a novel marsupial HAV (MHAV). The novel MHAV shared specific features with HAV, including hepatotropism, antigenicity, genome structure, and a common ancestor in phylogenetic reconstructions. Coevolutionary analyses revealed that host-independent evolutionary patterns contributed most to the current phylogeny of hepatoviruses and that MHAV was the most drastic example of a cross-order host switch of any hepatovirus observed so far. The divergence of marsupials from other mammals offers unique opportunities to investigate HAV species barriers and whether mechanisms of HAV immune control are evolutionarily conserved.

A new monoclonal antibody (Cox mAB 31A2) detects VP1 protein of coxsackievirus B3 with high sensitivity and specificity.

Human enteroviruses, e.g. coxsackieviruses, induce a variety of severe acute and chronic forms of disease, including myocarditis, meningitis and diabetes mellitus type 1. To visualize enterovirus infection with a diagnostic intent, many studies have applied a commercially available antibody (anti-CVB5 VP1, clone 5-D8/1, Dako, Hamburg, Germany) that identifies VP1 of different enteroviral serotypes. Many antibodies, however, have been found to bind non-specifically to proteins of cardiomyocytes and in the interstitial space, resulting in non-specific staining in immunohistochemistry. In this paper we show that the anti-CVB5 VP1 antibody, recognizing VP1 of coxsackieviruses and widely used in diagnostics and research, shows strong cross-reactivity with cellular proteins in the heart (and pancreas) of humans and mice, which calls for a more specific antibody to be used for diagnostic purposes. We observed by Western blot analyses of lysates from human heart tissue samples and HeLa cells two cross-reactive bands when using clone 5-D8/1. Peptide mass fingerprinting (MALDI-TOF) identified these proteins as creatine kinase (B-type) and tubulin, confirming that this mAb detects cellular proteins in addition to viral VP1. In order to overcome the problems of false positive VP1 staining we generated a new highly specific and sensitive monoclonal antibody (Cox mAB 31A2) that recognizes VP1 from CVB3. The new antibody was characterized and was found to function well in immunohistochemistry, immunofluorescence staining, Western blotting, ELISA and FACS analyses.

Acute hepatitis A virus infection in Turkey.

Anti-HAV IgM positive serum samples from acute phase hepatitis A patients from various areas in Turkey were tested for viral RNA by RT-PCR (reverse transcriptase polymerase chain reaction), using primer pairs from two different regions of the HAV genome. The PCR products amplified from both genomic regions underwent phylogenetic analyses. A comparison of the regions showed the same genotyping results, and the RT-PCR-2 in the 5'NCR demonstrated greater sensitivity compared to RT-PCR-1 in the VP1-P2A region. The majority of the isolates belonged to genotype IB and are related closely to each other; however, two isolates related even more strongly to the HAV HM175 strain. Two (n = 37) RT-PCR positive sera were classified under genotype IA. A surprising finding emerged for the mean levels of serum transaminases AST and ALT: higher levels were found in patients under 10 years of age compared to older patients. Anti-HAV IgM levels were determined quantitatively and, in addition, the HAV-RNA genome equivalents were ascertained by real time RT-PCR. No evidence was found for an association between viral load and the higher transaminase levels in the younger group.

Time course of hepatitis A viremia and viral load in the blood of human hepatitis A patients.

The hepatitis A virus (HAV) is the most common etiological cause of acute hepatitis infections in humans in industrialized countries. Investigations into the viral load during HAV viremia, however, are rare. Therefore, correlation studies between viral load, biochemical, and specific serological markers have been undertaken. The group of sera comprised a series of multiple consecutive blood samples drawn from 11 patients at different times after onset of the disease. During the period up to 70 days after the onset of icterus, the individual range was at 1 x 10(3) to 3 x 10(4) HAV genome equivalents/ml. From day 75 until 120 after onset of the disease, the levels traced were at 10(3). In one case, it was possible to trace 1.25 x 10(4) genome equivalents/ml up to 180 days after onset of icterus and in two cases even up to 408 and 490 days viral load levels of 5 x 10(3) and 4 x 10(4) were detected, respectively. The same sera were used to measure IgM class antibodies to hepatitis A virus and the total anti-HAV. The results demonstrate that a direct correlation to peak levels of viral load exists with peak serum transaminase levels, but neither with peak anti-HAV IgM levels nor with total anti-HAV. Decreasing amounts of anti-HAV IgM tend to occur with decreasing amounts of HAV genome equivalents; and, vice versa, increasing amounts of total anti-HAV are accompanied by decreasing amounts of HAV genome equivalents. The longest duration of viremia was found in patients infected with HAV genotype IA.