AG5 is a potent non-steroidal anti-inflammatory and immune regulator that preserves innate immunity

An archetypal anti-inflammatory compound against cytokine storm would inhibit it without suppressing the innate immune response. AG5, an anti-inflammatory compound, has been developed as synthetic derivative of andrographolide, which is highly absorbable and presents low toxicity. We found that the mechanism of action of AG5 is through the inhibition of caspase-1. Interestingly, we show with in vitro generated human monocyte derived dendritic cells that AG5 preserves innate immune response. AG5 minimizes inflammatory response in a mouse model of lipopolysaccharide (LPS)-induced lung injury and exhibits in vivo anti-inflammatory efficacy in the SARS-CoV-2-infected mouse model. AG5 opens up a new class of anti-inflammatories, since contrary to NSAIDs, AG5 is able to inhibit the cytokine storm, like dexamethasone, but, unlike corticosteroids, preserves adequately the innate immunity. This is critical at the early stages of any naïve infection, but particularly in SARS-CoV-2 infections. Furthermore, AG5 showed interesting antiviral activity against SARS-CoV-2 in humanized mice.

Nanobodies Protecting From Lethal SARS-CoV-2 Infection Target Receptor Binding Epitopes Preserved in Virus Variants Other Than Omicron

The emergence of SARS-CoV-2 variants that escape from immune neutralization are challenging vaccines and antibodies developed to stop the COVID-19 pandemic. Thus, it is important to establish therapeutics directed toward multiple or specific SARS-CoV-2 variants. The envelope spike (S) glycoprotein of SARS-CoV-2 is the key target of neutralizing antibodies (Abs). We selected a panel of nine nanobodies (Nbs) from dromedary camels immunized with the receptor-binding domain (RBD) of the S, and engineered Nb fusions as humanized heavy chain Abs (hcAbs). Nbs and derived hcAbs bound with subnanomolar or picomolar affinities to the S and its RBD, and S-binding cross-competition clustered them in two different groups. Most of the hcAbs hindered RBD binding to its human ACE2 (hACE2) receptor, blocked cell entry of viruses pseudotyped with the S protein and neutralized SARS-CoV-2 infection in cell cultures. Four potent neutralizing hcAbs prevented the progression to lethal SARS-CoV-2 infection in hACE2-transgenic mice, demonstrating their therapeutic potential. Cryo-electron microscopy identified Nb binding epitopes in and out the receptor binding motif (RBM), and showed different ways to prevent virus binding to its cell entry receptor. The Nb binding modes were consistent with its recognition of SARS-CoV-2 RBD variants; mono and bispecific hcAbs efficiently bound all variants of concern except omicron, which emphasized the immune escape capacity of this latest variant.

Akt Kinase Intervenes in Flavivirus Replication by Interacting with Viral Protein NS5

Arthropod-borne flaviviruses, such as Zika virus (ZIKV), Usutu virus (USUV), and West Nile virus (WNV), are a growing cause of human illness and death around the world. Presently, no licensed antivirals to control them are available and, therefore, search for broad-spectrum antivirals, including host-directed compounds, is essential. The PI3K/Akt pathway controls essential cellular functions involved in cell metabolism and proliferation. Moreover, Akt has been found to participate in modulating replication in different viruses including the flaviviruses. In this work we studied the interaction of flavivirus NS5 polymerases with the cellular kinase Akt. In vitro NS5 phosphorylation experiments with Akt showed that flavivirus NS5 polymerases are phosphorylated and co-immunoprecipitate by Akt. Polymerase activity assays of Ala- and Glu-generated mutants for the Akt-phosphorylated residues also indicate that Glu mutants of ZIKV and USUV NS5s present a reduced primer-extension activity that was not observed in WNV mutants. Furthermore, treatment with Akt inhibitors (MK-2206, honokiol and ipatasertib) reduced USUV and ZIKV titers in cell culture but, except for honokiol, not WNV. All these findings suggest an important role for Akt in flavivirus replication although with specific differences among viruses and encourage further investigations to examine the PI3K/Akt/mTOR pathway as an antiviral potential target.

A one-step TaqMan real-time qRT-PCR assay for the specific detection and quantitation of the Spanish goat encephalitis virus (SGEV)

Louping ill-like virus (LI) has been recently detected in two different locations in the north of Spain and separated by only around 400 km. Using molecular approaches, the viruses causing both outbreaks have been shown to be different to LI virus, but also different to each other. They have been called SSEV (Spanish sheep encephalitis virus) and SGEV (Spanish goat encephalitis virus) taking into account the species from which they were isolated. The aim of this paper was to design a quantitative TaqMan real-time RT-PCR protocol, for the specific diagnostic and quantitation of SGEV. Linearity, efficiency and dynamic range as well as reproducibility and specificity of the method has been tested and established. The method has proved to be valid for the specific detection and viral load quantitation of SGEV genome in virus isolates and tissue samples from infected animals. This assay will be a useful analytical tool in early diagnosis and epidemiological surveys.

First TBEV serological screening in Flemish wild boar

In the frame of a Flemish wildlife surveillance in 2013, a serological screening was performed on sera from wild boar (Sus scrofa; n=238) in order to detect tick-borne encephalitis virus (TBEV)-specific antibodies. Neutralising antibodies were titrated with a seroneutralisation test (SNT), using two cut-off titres (1/10–1/15). Seven wild boars were found TBEV-seropositive and showed moderate (>1/15) to high (>1/125) SNT-titres; three individuals had borderline results (1/10–1/15). This study demonstrated the presence of TBEV-specific antibodies in wild boar and highlighted potential TBEV-foci in Flanders. Additional surveillance including direct virus testing is now recommended.

Oculopathologic findings in flavivirus-infected gallinaceous birds

Using eye samples of nine 9-week-old experimentally West Nile virus (WNV)-infected red-legged partridges (Alectoris rufa), time course of lesions and WNV antigen appearance in ocular structures were examined. In addition, eye samples of 6 red-legged partridges and 3 common pheasants (Phasianus colchicus) naturally infected with Bagaza virus (BAGV) were used to study lesions and flavivirus antigen distribution in relation to apparent blindness in the former. The rapid onset of microscopic lesions and early presence of viral antigen in the eye of experimentally WNV-infected partridges, prior to the central nervous system involvement, suggested hematogenous spread of the virus into the eye. BAGV-infected partridges had a more pronunced inflammatory reaction and more widespread flavivirus antigen distribution in the retina compared with pheasants and experimentally fatally WNV-infected partridges. Our results suggest that flavivirus replication and development of lesions in ocular structures of gallinaceous game birds vary with the specific virus and host species involved.

Virus hazards from food, water and other contaminated environments

Numerous viruses of human or animal origin can spread in the environment and infect people via water and food, mostly through ingestion and occasionally through skin contact. These viruses are released into the environment by various routes including water run-offs and aerosols. Furthermore, zoonotic viruses may infect humans exposed to contaminated surface waters. Foodstuffs of animal origin can be contaminated, and their consumption may cause human infection if the viruses are not inactivated during food processing. Molecular epidemiology and surveillance of environmental samples are necessary to elucidate the public health hazards associated with exposure to environmental viruses. Whereas monitoring of viral nucleic acids by PCR methods is relatively straightforward and well documented, detection of infectious virus particles is technically more demanding and not always possible (e.g. human norovirus or hepatitis E virus). The human pathogenic viruses that are most relevant in this context are nonenveloped and belong to the families of the Caliciviridae, Adenoviridae, Hepeviridae, Picornaviridae and Reoviridae. Sampling methods and strategies, first-choice detection methods and evaluation criteria are reviewed.

Virus hazards from food, water and other contaminated environments

Numerous viruses of human or animal origin can spread in the environment and infect people via water and food, mostly through ingestion and occasionally through skin contact. These viruses are released into the environment by various routes including water run‐offs and aerosols. Furthermore, zoonotic viruses may infect humans exposed to contaminated surface waters. Foodstuffs of animal origin can be contaminated, and their consumption may cause human infection if the viruses are not inactivated during food processing. Molecular epidemiology and surveillance of environmental samples are necessary to elucidate the public health hazards associated with exposure to environmental viruses. Whereas monitoring of viral nucleic acids by PCR methods is relatively straightforward and well documented, detection of infectious virus particles is technically more demanding and not always possible (e.g. human norovirus or hepatitis E virus). The human pathogenic viruses that are most relevant in this context are nonenveloped and belong to the families of the Caliciviridae, Adenoviridae, Hepeviridae, Picornaviridae and Reoviridae. Sampling methods and strategies, first‐choice detection methods and evaluation criteria are reviewed.

Virus hazards from food, water and the environment, their reservoirs and routes of transmission; Sampling methods and sampling strategies thereof, including the first choice test methods, and criteria for data evaluation are described.

[Hepatitis E virus: zoonotic implications]

The Hepatitis E virus (HEV) is transmitted primarily by the feco-oral route throughout contaminated water and/or food, and is one of the main causes of acute hepatitis worldwide. Hepatitis E shows a high mobility but a low mortality rate, except in pregnant women, where it can be as high as 30%. HEV causes sporadic cases and epidemic outbreaks, mainly in Africa, Asia and Central America. In Europe, there is an increase in the number of reported autochthonous cases no related with travel to endemic areas. In addition, HEV also infects animals, including pigs, and its zoonotic potential has been recently demonstrated. In fact, porcine and human strains of the same area are genetically more closely related to each other than to strains of the same species but a different geographical region, and there are data suggesting that people in close contact with pigs presents a higher prevalence of specific anti-HEV antibodies. All together, these data have drove to an increase interest in determining the incidence of the disease in animals, its possible zoonotic risk, and its implications for human health. In the present article we revised the current knowledge about HEV, with special emphasis in the possible consequences of its zoonotic potential.

Hepatitis C virus population analysis of a single-source nosocomial outbreak reveals an inverse correlation between viral load and quasispecies complexity

The features of Hepatitis C virus (HCV) quasispecies within an envelope segment including the hypervariable region 1 were analysed at an early time point post-infection in seven patients that acquired HCV from a single common donor during a nosocomial outbreak. The grouping of patients according to viral load was reflected in the structure of the quasispecies. A higher viral load correlated with the presence of a predominant HCV genome and a corresponding lower quasispecies complexity. The quasispecies complexity itself was not correlated with HCV clearance or persistence. Thus, the relationship between an intrapatient HCV quasispecies and the clinical outcome of an HCV infection is more complex than previously anticipated.

Evolution of hepatitis C virus quasispecies immediately following liver transplantation

Liver cirrhosis caused by chronic hepatitis C virus (HCV) infection is the main indication for liver transplantation (LT). There is little information on HCV genetic evolution following transplantation. The aim of this study was to carefully assess early evolution of HCV quasispecies in a cohort of 18 liver transplant recipients followed prospectively. Quasispecies analysis was performed by sequence analysis of the hypervariable region 1 (HVR1) before transplantation and at day 4 and week 4 following LT. A predominant variant was present in 12 (67%) of the 18 patients before transplantation and the same variant was propagated and remained predominant after LT in 6 (50%) of these patients. In the remaining individuals, there were major changes in the quasispecies composition, mostly occurring during the first days after LT. There was a progressive decrease in the nonsynonymous (dN)/synonymous (dS) ratios from baseline (1.2) to day 4 (.6) (P = .08) and to week 4 after LT (.3) (P = .015). Similarly, genetic distance (GD) declined from baseline (.1) to day 4 (.03) (P = .07) and to week 4 (.04) (P = .04). We did not find any differences in HCV genetic evolution between patients with mild (n = 10) or severe (n = 8) disease recurrence. In conclusion, during the first days following transplantation, HCV quasispecies becomes more homogenous, even after major changes in its composition. Importantly, these changes persist and even increase during the 1st month after transplantation. The "bottleneck" effect caused by the implantation of a new graft and the lack of selective pressure due to the strong immunosuppression most likely explain this particular pattern of genetic evolution.

Antibody response after RSV infection in children younger than 1 year of age living in a rural area of Mozambique

Serological responses have been studied in respiratory syncytial virus (RSV) infected children < 1 year of age attending the outpatient department of the Manhiça District Hospital (Mozambique). Molecular characterization of viral RNA in nasopharyngeal aspirates from the infected children indicated a high level of genetic uniformity among the infecting viruses, all of which belonged to a single genotype of RSV group A. A representative virus strain, Moz00, was isolated from one of the infants and was used, together with the group A strain A2 and the group B strain 8/60, as antigens in the quantification of infant antibody responses. In this study, 97.5% (39/40) and 96.4% (27/28) of infected children produced an antibody response against Moz00 detected by the membrane fluorescent antibody test (MFAT) and the neutralization test (NT), respectively. Seroconversion rates decreased when the A2 and 8/60 strains were used as antigen in MFAT (95.4% and 88.2%, respectively) or NT (81.8% and 54.5%, respectively), indicating that antibody responses had both group- and strain-specific components. Antibodies in convalescent sera of infected children were compared with maternally derived antibodies detected in a group of children also < 1 year of age, but with no evidence of RSV infection. The convalescent sera exhibited reduced neutralizing capacity when the 8/60 strain was used as antigen (P = 0.028), suggesting that the infant antibody response lacks neutralizing capacity against strains of the heterologous virus group. Restricted cross-reactivity and neutralizing capacity of antibodies generated by young children might be expected to induce only moderate protection in subsequent epidemics against genetically distant strains.

Influence of human immunodeficiency virus type 1 subtype on mother-to-child transmission

The present study was designed to assess whether the subtype of human immunodeficiency virus type 1 (HIV-1) could affect the rate of HIV-1 mother-to-child transmission in a cohort of 31 HIV-1-seropositive pregnant Tanzanian women. In order to assign a subtype to the samples analysed, nucleotide sequencing of the HIV-1 long terminal repeat U3 and C2V3C3 envelope regions was performed from the sera of these 31 pregnant women. Except in three cases, amplification of both regions was achieved in all samples. Subtypes A (n=13, 46 %), C (n=6, 21 %) and D (n=2, 7 %), as well as a number (25 %) of A/C, C/A, D/A and C/D recombinant forms (n=3, 2, 1 and 1, respectively), were identified. Of the 31 HIV-1 seropositive pregnant women analysed, eight (26 %) transmitted HIV-1 to their infants. Among the eight transmitter mothers, four (4 of 13, 31 %) were infected with HIV-1 subtype A, one (1 of 6, 17 %) with HIV-1 subtype C, none (0 of 2, 0 %) with HIV-1 subtype D and three (3 of 7, 43 %) with HIV-1 subtype recombinant A/C. These findings show no significant differences in the mother-to-child transmissibility of HIV-1 subtypes A, C and D and detected recombinants forms.

Prevalence of respiratory syncytial virus IgG antibodies in infants living in a rural area of Mozambique

A case control study was carried out in Manhiça (Mozambique). Serum samples were collected from infants < 1 year of age in hospital to assess the effect of serum antibodies on the incidence of respiratory syncytial virus (RSV) infection. Sera were collected from a total of 31 cases of RSV infection and paired uninfected controls matched for age and sex. Anti-RSV antibodies were assessed by a membrane fluorescent antibody test (MFAT) for immunoglobulin G (IgG) antibodies and by a neutralizing antibody test. IgG RSV antibodies were of higher prevalence and at higher levels in the control group when compared to the infected case group (P < 0.001), indicating an important role for IgG antibodies in protection. To assess infection before recruitment, IgA RSV antibodies were also measured by MFAT. IgA RSV antibody prevalence was very low in patients and controls (0/31 and 4/31 respectively), suggesting that most of the detected IgG RSV antibody in both groups was of maternal origin. Re-analysis of data from the subset of 27 matched, IgA RSV antibody negative infant pairs mirrored the full analysis indicating that maternal antibody has an important role in RSV protection. Similar results were obtained when neutralizing antibodies were measured and when the measurement was done against subgroup A virus strain A2, subgroup B virus strain 8/60 and a contemporary subgroup A isolate, Moz00. No significant differences in the reactivity of maternal antibodies with the three virus strains were observed. The data described below represent the first analysis of the role of maternal antibodies in reducing the risk of pediatric infection in developing countries. The results reinforce the concept of maternal vaccination for the control of RSV in very young children in whom the risk and severity of infection are the highest.

High amino acid variability within the NS5A of hepatitis C virus (HCV) is associated with hepatocellular carcinoma in patients with HCV-1b-related cirrhosis

Interferon therapy may decrease the risk of hepatocellular carcinoma in patients with hepatitis C virus (HCV)-related liver cirrhosis. Interaction of the cellular protein kinase PKR with the PKR-binding domain (PKR-bd) of HCV-NS5A protein may affect cellular growth control and viral resistance to interferon therapy. Mutations within the PKR-bd, which comprises the interferon sensitivity determining region (ISDR), have been associated with interferon sensitivity. To determine whether or not there is an association between HCV heterogeneity and the presence of hepatocellular carcinoma, HCV-1b genomic regions were amplified and directly sequenced from serum samples obtained from 82 patients with liver cirrhosis, 53 with, and 29 without hepatocellular carcinoma. None of them had received antiviral therapy. When compared with the deduced consensus sequence, the median number of amino acid changes in the PKR-bd was higher among samples from patients with (4.22) than from those without hepatocellular carcinoma (1.62; P <.001), and isolates with 3 or more amino acid changes were significantly more common among the former (60%) than among the later (6%, P <.001). No such differences were observed in other viral regions, including Core, E2-HVR-1, E2-PePHD, NS3, and the 5' and 3' PKR-bd flanking regions. In addition, amino acid variation in viral regions other than HVR-1 did not accumulate over time in the analyzed sequential serum samples obtained from patients with or without hepatocellular carcinoma. Therefore, a mutated HCV-PKR-bd phenotype is very common in cirrhotic patients with hepatocellular carcinoma.

Genetic evolution of GB virus C/hepatitis G virus (GBV-C/HGV) under interferon pressure

The epidemiology and clinical features of chronic GBV-C/HGV infection have largely been explored, but there is little information about the mechanisms enabling GBV-C/HGV to cause persistent infection. Since analysis of the genomic variation of GBV-C/HGV under interferon pressure might provide some insight into this issue, we analyzed the nucleotide sequence variation of the 5'NC and NS3 regions in GBV-C/HGV isolates obtained sequentially from seven patients co-infected with HCV and treated with interferon. A reduction of GBV-C/HGV-RNA serum level below the detection limit of the RT-PCR assay was observed during treatment in all patients, but upon interferon withdrawal, viral RNA remained undetectable in only two patients. Among the five patients who did not clear GBV-C/HGV-RNA, viral strains emerging after treatment were identical to those present at baseline in three cases. In a further case, in whom GBV-C/HGV-RNA re-emerged during therapy (breakthrough episode), several mutations appeared in relapse samples. In the remaining patient, with a mixed infection before therapy, only one of the two GBV-C/HGV strains present at baseline was detected upon treatment withdrawal. These data raise the possibility that positive selection may act over GBV-C/HGV genome during interferon therapy, and contribute to persistence of infection with this virus.

Prevalence and route of transmission of infection with a novel DNA virus (TTV), hepatitis C virus, and hepatitis G virus in patients infected with HIV

OBJECTIVES

To evaluate the prevalence, route of transmission and clinical significance that current co-infection with TT virus (TTV), hepatitis C virus (HCV), and hepatitis G virus (HGV) have in HIV-1-infected patients.

DESIGN

Presence of TTV, HCV, and HGV was analyzed in plasma samples from 160 HIV-1-infected patients with parenteral (38 intravenous drug users [IVDUs] and 41 patients with hemophilia) or sexual (39 homosexuals and 42 heterosexuals) risk of exposure, and in 168 volunteer blood donors. Alanine aminotransferase (ALT) levels and CD4+ counts were also analyzed.

METHODS

HCV and HGV RNA were detected by specific reverse transcriptase (RT) nested polymerase chain reaction (PCR) and TTV DNA by specific heminested PCR.

RESULTS

TTV DNA was detected in 39% of the patients and in 14% of the volunteer blood donors. HCV and HGV infections were detected in 42% and in 14% of the patients, and in 0% and 3% of the blood donors, respectively. Prevalences of TTV and HCV infection were higher among patients with parenteral (62% and 68%) than in those with sexual (17% and 16%) risk of exposure. A higher prevalence of TTV infection (but not of HCV or HGV infection) was observed among patients with hemophilia (76%) than IVDUs (47%), and among homosexuals (26%) than among heterosexuals (10%). Abnormal ALT levels were related with the presence of HCV infection, independently of the detection of TTV DNA. TTV infection did not seem to alter the levels of CD4+ T cells.

CONCLUSIONS

Prevalence of current TTV infection is high among HIV-infected patients with parenteral risk of exposure, but TTV is also transmitted through sexual routes; detection of TTV does not seem to influence the clinical or immune status of HIV-infected patients.

Molecular evidence of mother-to-infant transmission of hepatitis G virus among women without known risk factors for parenteral infections

Hepatitis G virus (HGV) RNA was detected in 18 of 133 pregnant women from Tanzania without known risk factors for HGV infection and in 7 of 18 children born to HGV RNA-positive mothers. Molecular evidence of mother-to-infant transmission was obtained only for three of seven children. HGV RNA was also detected in 4 of 42 children born to non-HGV-infected women. Thus, mechanisms other than materno-filial may play an important role in HGV transmission during early childhood.

Infection with a novel human DNA virus (TTV) has no pathogenic significance in patients with liver diseases

BACKGROUND/AIMS

A recently identified DNA virus, termed TT virus (TTV), has been associated with post-transfusional hepatitis, and a high prevalence of TTV infection in patients with acute or chronic liver disease of unknown etiology has been reported from Japan, but few data are available about TTV infection in other countries.

METHODS

Using hemi-nested-PCR amplification to detect TTV-DNA sequences in serum, we investigated TTV infection in blood donors and in patients with liver diseases of varied etiology.

RESULTS

The prevalence of TTV infection was 13.7% in blood donors (23/168), 18.6% in chronic hepatitis C (19/102), 28.6% in chronic hepatitis B (16/56), 29.9% in hepatocellular carcinoma (20/67), 9.1% in cryptogenic chronic liver disease (2/22) and 39.6% in fulminant hepatitis (19/48). The prevalence of TTV infection in patients with virus-induced or idiopathic fulminant hepatitis was similar. Comparison of TTV-infected and non-infected patients did not reveal significant differences concerning demographic, epidemiological or histopathological features. In patients with hepatitis C, response to interferon therapy was not related to TTV infection. Phylogenetic analysis of TTV isolates showed that at least three different types of TTV are present in Spain.

CONCLUSIONS

Our data suggest that TTV infection is frequent among blood donors and patients with acute liver disease. However, pathogenic effects associated with TTV infection were not observed.

Genetic evolution of hepatitis G virus in chronically infected individual patients

Comparative sequence analysis of different isolates of hepatitis G virus (HGV) has demonstrated significant intersubject genetic heterogeneity, but few data on intrasubject genetic evolution have been reported. To further investigate the genetic diversification of the HGV genome, 36 plasma samples from eleven patients chronically infected with HGV serially obtained 2-4 years apart were analysed. We determined the viral nucleotide sequence of the 5' non-coding (NC) and the NS3 regions by directly sequencing the RT-PCR amplified products obtained from the viral RNAs. Intrasubject sequence variation was found to be 1.3-2.4 x 10(-3) base substitutions per genome site per year within the 5' NC region and 1.3-9.4 x 10(-3) base substitutions per genome site per year within the NS3 region. Depending on the genomic region analysed (i.e. 5' NC or NS3 region), pairwise comparisons and phylogenetic reconstructions showed that intersubject genetic distances were 17.5- to 20.8-fold greater than intrasubject ones. Overall, the evolution rate of HGV in the regions analysed is not significantly different from that found in hepatitis C virus.

Prevalence and genotypes of GB virus C/hepatitis G virus (GBV-C/HGV) and hepatitis C virus among patients infected with human immunodeficiency virus: evidence of GBV-C/HGV sexual transmission

The development of new antiretroviral agents may improve survival of HIV-infected individuals, and therefore chronic viral hepatitis may become more relevant in these patients. The presence of GBV-C/HGV and hepatitis C virus (HCV) RNA were investigated by reverse transcriptase-nested polymerase chain reaction in plasma from 168 Spanish HIV-infected patients belonging to four different risk groups: intravenous drug users (IVDUs), hemophiliacs, homosexuals, and heterosexuals. GBV-C/HGV-RNA and HCV-RNA were detected in 18% and 43% of the patients, respectively. The prevalence of current infection with these viruses was notably high, 19% for GBV-C/HGV and 69% for HCV, among individuals with parenteral risk of infection (intravenous drug abusers and hemophiliacs), but sexual transmission with GBV-C/HGV was also suggested because 16.5% of patients with sexual risk, either homosexual or heterosexual, had GBV-C/HGV-RNA in plasma. Although investigation of GBV-C/HGV-RNA possibly underestimates the actual prevalence of infection with GBV-C/HGV, the above data suggest that sexual contact may play a relevant role in the spread of this virus. Phylogenetic analysis showed no evidence for clustering of NS3 sequences into different genotypes or subtypes of GBV-C/HGV.

Hepatitis G virus infection in a haemodialysis unit: prevalence and clinical implications

BACKGROUND

Hepatitis viruses have become one of the main infectious problems in patients on long-term haemodialysis. A new RNA virus, designated hepatitis G virus (HGV) has been recently identified. The pathogenic relevance of this virus is currently under investigation. The aim of this study was to analyse the prevalence and clinical implications of hepatitis G virus infection in patients on haemodialysis.

METHODS

The presence of HGV-RNA was investigated in 96 patients on maintenance haemodialysis. Hepatitis viral markers (HBsAg, anti-HCV, HGV-RNA) and liver tests were assessed in all these patients, as well as the risk factors for hepatitis viruses acquisition. As a control group, 200 blood donors were tested for the presence of HGV-RNA.

RESULTS

HGV-RNA was detected in 25 of 96 patients on haemodialysis (26%) and in six of 200 blood donors (3%) (P < 0.001). Thirteen of 25 HGV infected patients (52%) were coinfected with other hepatitis viruses (HBV and/or HCV). Evidences of chronic liver disease were more frequent in patients infected by HBV and/or HCV (61%) than in patients infected by HGV alone (17%) (P = 0.01). Although 80% of HGV infected patients had received blood products, the transfusion rate was not different from non HGV-infected patients. Time on haemodialysis was significantly shorter in patients infected with HGV alone (3.1 +/- 3.5 years) compared to patients infected with HBV and/or HCV (7.6 +/- 5.8 years) (P = 0.04).

CONCLUSIONS

Patients on maintenance haemodialysis are at increased risk for HGV infection. HGV infection itself does not seem to be a frequent cause of chronic liver disease in these patients. Since the prevalence of HGV infection in blood donors is high, blood transfusion could be one of the main factors implicated in HGV transmission in patients on haemodialysis.

Antigenic stability of foot-and-mouth disease virus variants on serial passage in cell culture

Two neutralizing monoclonal antibody (MAb)-resistant variants selected from an isolate of foot-and-mouth disease virus (FMDV) type A5 were repeatedly passaged in cell culture and monitored for susceptibility to neutralization by the selecting MAb. A variant isolated with a MAb to a conformational epitope (1-OG2) lost resistance in 20 passages, while a variant isolated with a MAb to a linear epitope (1-HA6) persisted for 30 passages. In both cases, the virus population emerging after passage was antigenically and genetically indistinguishable from the original wild-type parental virus (FMDV A5 Spain-86). Coinfection assays with the wild type and each variant, and between the variants, showed rapid conversion to a homogeneous population. Wild-type virus prevailed over the variants and for coinfection between the variants, the linear epitope variant 1-HA6. While both variants arose from a single nucleotide substitution and reversion to wild type occurred for each, it appears that the variant based on the continuous epitope (1-HA6) was more stable. We discuss the implications of these results for the antigenic diversity of FMDV and its relationship to virus evolution.

Identification of neutralizing antigenic sites on VP1 and VP2 of type A5 foot-and-mouth disease virus, defined by neutralization-resistant variants

Five neutralizing monoclonal antibodies (nMAbs) obtained against type A5 Spain-86 foot-and-mouth disease virus were used to generate a series of neutralization-resistant variants. In vitro and in vivo assays showed that the variants were fully refractory to neutralization by the selecting nMAb. On the basis of cross-neutralization and binding assays, two neutralizing antigenic sites have been located on the virus surface; one, located near the C-terminus of VP1, displayed a linear epitope, and the second, located on VP2, displayed two conformational epitopes. Nucleotide sequencing of RNA of the parental and variant capsid protein-coding region P1 has placed the amino acid changes at position 198 of VP1 for the first site and at positions 72 and 79 of VP2 for the related epitopes in the second site. The relative importance of these two sites in the biological properties of foot-and-mouth disease virus is discussed.

Detection of foot-and-mouth disease virus by competitive ELISA using a monoclonal antibody specific for the 12S protein subunit from six of the seven serotypes

Foot-and-mouth disease (FMD) prevention and control programs are dependent upon rapid, reliable diagnostic procedures. The widely used FMD diagnostic complement fixation (CF) procedures require a specific antiserum for each of the seven FMDV serotypes making the tests both cumbersome and difficult to standardize. An FMD diagnostic, monoclonal antibody based inhibition-ELISA procedure was developed. The test uses a single monoclonal antibody (MAb) that reacts with all European and South American FMDV isolates examined. The procedure detects a highly conserved epitope on the 12S protein subunit of FMDV which appears to be common to all FMDV's with the exception of the South African Territories 2 serotype. The results indicate that the sensitivity of this test is greater than CF and approaches that of virus isolation.

African swine fever virus: purification of capsomeres released by lipase

The virus capsomeres of the outer and inner layers of capsids were effectively released simultaneously from purified virions by lipase digestion and were purified by a linear gradient ultracentrifugation. The capsid consisted of an array of double layers of uniformly arranged individual capsomeres where a lipid(s) served as a matrix in between the capsomeres.

Comparison of vaccine strains and the virus causing the 1986 foot-and-mouth disease outbreak in Spain: epizootiological analysis

RNAs of the most recent foot-and-mouth disease virus isolated in Spain (A5Sp86) during the 1986 outbreak, and of the three vaccine strains in use at that time in that country, have been compared. Although these viruses are serologically indistinguishable, differences have been found among them by T1 fingerprinting. This genetic heterogeneity affects the immunogenic VP1 gene, with amino acid changes located at the carboxyterminal end of the molecule. VP1-coding sequences obtained have been compared with those previously reported for European A5 FMDVs and it has been possible to trace their phylogenetic origin. The most parsimonious evolutionary tree obtained shows that the viruses analyzed are closely related to those previously isolated in 1983 in Spain, Portugal and Morocco. In spite of the VP1 sequence homology shown by this group of viruses, the genetic distances among field isolates and vaccine strains are significantly shorter than the distances found among field isolates. Thus, a significant relationship among virus recovered from recent outbreaks and the vaccine strains in use at that time in Spain, has been obtained.

Antigenic comparison of different foot-and-mouth disease virus types using monoclonal antibodies defining multiple neutralizing epitopes on FMDV A5 subtypes

Thirteen monoclonal antibodies (MAbs) were elicited with A5 Spain-86 virus, the cause of the most recent foot-and-mouth disease virus (FMDV) outbreak in Spain. The MAbs were tested for ability to bind 140S virions and 12S protein subunits by liquid-phase radioimmunoassay (RIA), and to bind VP1 capsid protein by Western immunoblot assay. One of the thirteen MAb was virion (140S) specific, seven recognized 140S and 12S subunits, one bound to 140S, 12S and VP1 and four were 12S specific. These MAbs presented varying binding patterns when tested against different FMDV subtypes and serotypes, indicating the presence of conserved and non-conserved epitopes among FMDV serotypes and subtypes. Neutralization assays, in vivo and in vitro, showed that none of the 140S specific MAbs or 12S specific MAbs were neutralizing, but notably several of the 12S specific MAbs bound to all the different FMDV serotypes and can be useful diagnostic reagent for the detection of FMDV. The remaining MAbs showed varying behavior with the different types tested: not all types to which the MAbs bound were neutralized, demonstrating that the presence of an epitope and subsequent neutralization of infectivity are not necessarily correlated. Five type A12 neutralizing MAbs, previously characterized, have been used in this work. Four bound to A5 Spain-86 virus, but only one neutralized viral infectivity. On the basis of differential reactivity and neutralization among various FMDV subtypes and serotypes, and cross-inhibition binding assays between these MAbs, seven neutralization related epitopes have been defined on A5 Spain-86 virus.