The incidence of HIV-2 infection in Spain is declining - a registry data analysis.

OBJECTIVES: HIV-2 infection is a neglected disease caused by a human retrovirus that causes AIDS more slowly than HIV-1. Infection with HIV-2 is endemic in West Africa. Given its differential features, guidelines recommend ruling out HIV-2 infection in all newly diagnosed HIV-seropositive individuals. METHODS: A national registry of HIV-2 cases was created in Spain in 1989, following the first report of three HIV-2+ individuals in Barcelona. The main demographics, clinical, and virological data are reported up to December 2023. RESULTS: A total of 424 individuals with HIV-2 infection were recorded in the Spanish registry. After a peak in 2009 when 31 cases were reported, new HIV-2 diagnoses steadily decreased. Less than 10 cases/year have been notified since the COVID-19 pandemic. In 2023, only eight cases were reported. Mean age at HIV-2 diagnosis was 44 years old, ranging from birth to 83 years. A total of 265 (62.5%) were male. Migrants predominated, being 322 (76%) Sub-Saharan Africans; however, 60 (14.2%) were native Spaniards. Heterosexual exposure was the most likely route of infection in at least 287 (67.7%) cases. A few cases could be traced to transfusions (n = 4), vertical infection (n = 2), or injection drug use (n = 7). In addition, 15 individuals (3.5%) were men who had sex with men. Coinfection with HIV-1 was recognized in 39 (9.2%) individuals. Molecular characterization of HIV-2 subtypes was performed in 139 individuals, 121 being infected with subtype A and 18 with subtype B. CONCLUSION: The annual incidence of HIV-2 infection in Spain has decreased after peaking 15 years ago, being the current number of cases below 10 per year. Three-quarters are African migrants, and two-thirds are male. Circulation of HIV-2 in Spain is limited and steadily decreasing.

Prospects for Controlling Hepatitis B Globally.

Infection with the hepatitis B virus (HBV) is highly prevalent globally. Over 250 million people suffer from chronic hepatitis B, and more than 800,000 patients die each year due to hepatitis B complications, including liver cancer. Although protective HBV vaccines are recommended for all newborns, global coverage is suboptimal. In adults, sexual transmission is by far the most frequent route of contagion. The WHO estimates that 1.5 million new HBV infections occur annually. Oral nucleos(t)ide analogues entecavir and tenofovir are the most frequent antivirals prescribed as HBV therapy. Almost all patients adherent to the medication achieve undetectable plasma viremia beyond 6 months of monotherapy. However, less than 5% achieve anti-HBs seroconversion, and viral rebound occurs following drug discontinuation. Therefore, nucleos(t)ide analogues need to be lifelong. New long-acting formulations of tenofovir and entecavir are being developed that will maximize treatment benefit and overcome adherence barriers. Furthermore, new antiviral agents are in development, including entry inhibitors, capside assembly modulators, and RNA interference molecules. The use of combination therapy pursues a functional HBV cure, meaning it is negative for both circulating HBV-DNA and HBsAg. Even when this goal is achieved, the cccDNA reservoir within infected hepatocytes remains a signal of past infection, and HBV can reactivate under immune suppression. Therefore, new gene therapies, including gene editing, are eagerly being pursued to silence or definitively disrupt HBV genomes within infected hepatocytes and, in this way, ultimately cure hepatitis B. At this time, three actions can be taken to push HBV eradication globally: (1) expand universal newborn HBV vaccination; (2) perform once-in-life testing of all adults to identify susceptible HBV persons that could be vaccinated (or re-vaccinated) and unveil asymptomatic carriers that could benefit from treatment; and (3) provide earlier antiviral therapy to chronic HBV carriers, as being aviremic reduces the risk of both clinical progression and transmission.

Prevalence of HTLV-1/2 infection in pregnant women in Central and South America and the Caribbean: a systematic review and meta-analysis.

BACKGROUND: Human T-lymphotropic viruses (HTLV)-1 infection is endemic in many countries of Central and South America and Caribbean (CSA&C). Neither screening nor surveillance programs exist for HTLV-1/2 infection among pregnant women in this region. Neither in Western nations with large migrant flows from HTLV-1/2 endemic regions. METHODS: Systematic review and meta-analysis of the prevalence of HTLV-1/2 infection among CSA&C pregnant women. We included studies searching EMBASE, PubMed/MEDLINE, Scopus, and Web of Science from inception to February 15, 2023. This systematic review followed Preferred Reporting Items for Systematic Reviews and Meta-Analyses reporting guidelines. RESULTS: We identified a total of 620 studies. Only 41 were finally included in the meta-analysis. Most studies (61.0%) were from Brazil and Peru (14.6%). The total number of participants was 343,707. The pooled prevalence of HTLV-1/2 infection among CSA&C pregnant women was 1.30% (95% CI: 0.96-1.69) using anti-HTLV-1/2 antibody screening tests. There was a high heterogeneity (I2 = 98.6%). Confirmatory tests gave an HTLV-1 infection rate of 1.02% (95% CI: 0.75-1.33). CONCLUSIONS: The prevalence of HTLV-1/2 infection among CSA&C pregnant women is 1.3%, most cases being HTLV-1. This rate is greater than for other microbial agents regularly checked as part of antenatal screening (such as HIV, hepatitis B, or syphilis). Thus, HTLV-1/2 antenatal testing should be mandatory among CSA&C pregnant women everywhere.

Screening for HTLV-1 infection should be expanded in Europe.

Human T-cell lymphotropic virus type 1 (HTLV-1) infection is spreading globally at an uncertain speed. Sexual, mother-to-child, and parenteral exposure are the major transmission routes. Neither vaccines nor antivirals have been developed to confront HTLV-1, despite infecting over 10 million people globally and causing life-threatening illnesses in 10% of carriers. It is time to place this long-neglected disease firmly into the 2030 elimination agenda. Current evidence supports once-in-life testing for HTLV-1, as recommended for HIV, hepatitis B and C, along with targeted screening of pregnant women, blood donors, and people who attended clinics for sexually transmitted infections (STIs). Similar targeted screening strategies are already being performed for Chagas disease in some Western countries in persons from Latin America. Given the high risk of rapid-onset HTLV-1-associated myelopathy, universal screening of solid organ donors is warranted. To minimize organ wastage, however, the specificity of HTLV screening tests must be improved. HTLV screening of organ donors in Europe has become mandatory in Spain and the United Kingdom. The advent of HTLV point-of-care kits would facilitate testing. Finally, increasing awareness of HTLV-1 will help those living with HTLV-1 to be tested, clinically monitored, and informed about transmission-preventive measures.

Human T-lymphotropic virus-1 infection among Latin American pregnant women living in Spain.

Objectives: Human T-lymphotropic virus (HTLV) antenatal screening is not mandatory in Spain. Surveys conducted decades ago reported HTLV-1 seroprevalence rates of 0.2% among foreign pregnant women in Spain. The migrant flow to Spain from HTLV-1 endemic regions in Latin America and sub-Saharan Africa has increased during the last decade. Currently, 25% of pregnant women in Spain are foreigners. Methods: From January 2021 to October 2023 a cross-sectional study was carried out in all consecutive pregnant women attended at eleven Spanish clinics. A commercial enzyme immunoassay (EIA) was used for screening of serum HTLV-1/2 antibodies. Reactive samples were confirmed by immunoblot. Results: A total of 9813 pregnant women with a median age of 34 years-old were examined. Native Spaniards were 6977 (76.5%). Of 2147 foreigners (23.5%), 903566 (9.9%) were Latin Americans, 416 (4.5%) North Africans, 293 (3.2%) from Romania, and 196 (2.1%) from sub-Saharan Africa. A total of 47 samples were EIA reactive but only five were confirmed as HTLV-1 positive using immunoblot. Infected women came from Paraguay, Colombia, the Dominican Republic, Venezuela and Peru. All but one were primigravida, with ages ranging from 20 to 33 years-old. One was HIV-1 positive, and another was infected with Chlamydia trachomatis. Conclusion: The overall seroprevalence for HTLV-1 among pregnant women in Spain is 0.05% but rises ten-fold (0.55%) among Latin Americans. This rate is higher than in surveys conducted decades ago. Our results support that anti-HTLV testing should be part of antenatal screening in Spain in pregnant women coming from Latin America, as it is already done with Chagas disease.

Pre-exposure prophylaxis of non-HIV viral infections and the role of long-acting antivirals.

Viruses cause a large burden of human infectious diseases. During the past 50 years, antivirals have been developed to treat many pathogenic viruses, including herpesviruses, retroviruses, hepatitis viruses, and influenza. Besides being used as treatment, antivirals have shown efficacy for preventing certain viral infections. Following the success in the HIV field, a renewed interest has emerged on the use of antivirals as prophylaxis for other viruses. The development of formulations with extended half-life has pushed further this consideration in persons at risk for a wide range of viral infections. In this way, long-acting antivirals might behave as "chemovaccines" when classical vaccines do not exist, cannot be recommended, immune responses are suboptimal, escape mutants emerge, and/or immunity wanes. Five main caveats would temper its use, namely, selection of drug resistance, drug interactions, short- and long-term side effects, potential teratogenicity in women of child-bearing age, and high cost. Herein, we discuss the prospects for long-acting antivirals as prophylaxis of human viral infections other than HIV.

HTLV infection in persons with sexually transmitted diseases in Spain.

Background: HTLV-1 infection is a neglected disease, despite estimates of 10 million people infected worldwide and producing life-threatening illnesses in 10% of carriers. Sexual transmission is the main route of contagion. However, HTLV-1 is not listed among sexually transmitted infections (STIs). Methods: Serum from all consecutive individuals who had attended six STI clinics across Spain during the last 12 months were tested for HTLV antibodies using a commercial enzyme immunoassay (EIA). Reactive samples were confirmed by immunoblot. Results: A total of 2,524 samples were examined. The majority (1,936; 76.7%) belonged to men, of whom 676 (34.9%) were men who have sex with men (MSM) receiving HIV pre-exposure prophylaxis. Although native Spaniards predominated (1,470; 58.2%), up to 593 (23.5%) came from Latin America and 139 (5.5%) were African. A total of 26 individuals were initially EIA reactive and immunoblot confirmed 5 as HTLV-1 and 7 as HTLV-2. All but one HTLV-1+ case came from Latin America. Three were men and two were women. Among Latin Americans, the HTLV-1 seroprevalence was 0.67%. In contrast, all seven HTLV-2+ were native Spaniards and former injection drug users, and all but one were HIV+. Conclusion: The rate of HTLV infection among individuals with STIs in Spain is 0.5%, which is greater than in the general population. These results support the introduction of universal HTLV screening in persons who attend clinics for STIs.

HTLV-1-associated myelopathy in Spain.

BACKGROUND: HTLV-1 infection is a neglected disease. Over 10 million people are infected worldwide, with hot spots of high endemicity across all continents. Roughly 5% of HTLV-1 carriers develop HTLV-1-associated myelopathy (HAM), a progressive subacute neurological disabling disease. METHODS: We report the main features of patients diagnosed with HAM up to date in Spain, a non-endemic country with a relatively high migrant flow from Latin America and Equatorial Africa, where HTLV-1 is endemic. RESULTS: A total of 451 cases of HTLV-1 had been recorded in Spain until the end of year 2022. HAM had been diagnosed in 58 (12.9%). The current incidence is of 2-3 new cases per year. Women represent 76%. Mean age at diagnosis is 49 years-old. Nearly 60% are Latin Americans. Although sexual transmission is the most likely route of HTLV-1 acquisition, up to 6 individuals had been infected following solid organ transplantation. Rapid onset myelopathy developed in all but one of these transplant recipients from three HTLV-1-positive donors. HTLV-1 subtype 1a transcontinental was the only variant recognized in HAM patients. HTLV-1 proviral load was significantly greater in HAM patients than in asymptomatic HTLV-1 carriers (677 vs 104 HTLV-1 DNA copies/104 PBMC; p = 0.012). Symptom relief medications and physiotherapy have been the only treatment providing some benefit to HAM patients. Neither significant clinical nor virological efficacy was noticed using antiretrovirals in at least 9 HAM patients. Two thirds of HAM patients ended up in a wheelchair and with urinary/fecal sphincter incontinence. CONCLUSION: HAM is the most frequent clinical manifestation of HTLV-1 infection in Spain, a non-endemic country. Middle aged women migrants from Latin America are the most frequently affected. Two thirds end up in a wheelchair despite using antiretroviral therapy.

Adult T-cell leukemia/lymphoma in HTLV-1 non-endemic regions.

BACKGROUND: HTLV-1 infection is a neglected disease, despite producing neurological and lymphoproliferative severe illnesses and affect over 10 million people worldwide. Roughly 5% of HTLV-1 carriers develop Adult T-cell leukemia/lymphoma (ATLL), one of the most aggressive hematological malignancies. METHODS: A national HTLV-1 register exists since 1989 in Spain, a non-endemic country with a large migrant flow from Latin America and Equatorial Africa, where HTLV-1 is endemic. The main features of all patients diagnosed with ATLL in Spain up to date are reported. RESULTS: A total of 451 cases of HTLV-1 infection had been reported in Spain until the end of year 2022. ATLL had been diagnosed in 35 (7.8%). The current average incidence of ATLL in Spain is of two cases per year. Women represent 57% of ATLL patients. Mean age at diagnosis was 47 years-old. Roughly 57% were Latin Americans and 26% Africans. At diagnosis, the majority presented with acute or lymphoma clinical forms. Survival was shorter than one year in most of them. Mean HTLV-1 proviral load was significantly greater in ATLL patients than in asymptomatic HTLV-1 carriers (2,305 vs 104 copies/104 PBMC). HTLV-1 subtyping in 6 ATLL patients found the 1a transcontinental variant (n = 4) and the Japanese variant (n = 2). All ATLL patients were negative for HIV-1, did not develop HTLV-1-associated myelopathy and were not transplant recipients. CONCLUSION: The rate of ATLL is very low in Spain and mostly associated to migrants from HTLV-1 endemic regions. Given the poor clinical outcome of ATLL, HTLV-1 testing should be performed at least once in all migrants coming from HTLV-1 endemic countries and in natives who have lived in or had sex partners from such regions.

Genetic signature detected in T cell receptors from patients with severe COVID-19.

Characterization of host genetic factors contributing to COVID-19 severity promises advances on drug discovery to fight the disease. Most genetic analyses to date have identified genome-wide significant associations involving loss-of-function variants for immune response pathways. Despite accumulating evidence supporting a role for T cells in COVID-19 severity, no definitive genetic markers have been found to support an involvement of T cell responses. We analyzed 205 whole exomes from both a well-characterized cohort of hospitalized severe COVID-19 patients and controls. Significantly enriched high impact alleles were found for 25 variants within the T cell receptor beta (TRB) locus on chromosome 7. Although most of these alleles were found in heterozygosis, at least three or more in TRBV6-5, TRBV7-3, TRBV7-6, TRBV7-7, and TRBV10-1 suggested a possible TRB loss of function via compound heterozygosis. This loss-of-function in TRB genes supports suboptimal or dysfunctional T cell responses as a major contributor to severe COVID-19 pathogenesis.

Impact of the COVID-19 pandemic on hospital admissions due to viral hepatitis in Spain.

BACKGROUND: Before the advent of COVID-19 vaccines, hospitalizations due to SARS-CoV-2 infection during 2020 collapsed most medical centers worldwide. Disruptions in health care for clinical conditions other than COVID-19 were not uniform. Herein, we report the impact of COVID-19 on hospitalizations due to viral hepatitis in Spain. METHODS: Retrospective study of all hospitalizations in Spain during 10 months before (pre-pandemic period) and after (pandemic period) March 1st 2020. Admissions with a diagnosis of hepatitis B, C and/or delta were retrieved and compared using the Spanish National Registry of Hospital Discharges. RESULTS: Nationwide hospitalizations declined 14.6% during the pandemic period, from 3,144,164 to 2,684,845. This reduction was significantly more pronounced for admissions due to viral hepatitis (18.1% drop), falling from 46,521 to 38,115. During the pandemic period, patients admitted with viral hepatitis died significantly more frequently than during the pre-pandemic period (7.2% vs 6.1%; p < 0.001). Liver transplants significantly declined during the pandemic period. COVID-19 was diagnosed in 10.3% of patients hospitalized with viral hepatitis during the pandemic period. This subset of patients was older and died 2.4-fold more frequently than the rest, despite having advanced liver disease less frequently. CONCLUSION: Hospitalizations due to viral hepatitis significantly declined in Spain during the COVID-19 pandemic. Patients admitted with viral hepatitis experienced a greater mortality during the pandemic period. Deaths were more pronounced when coinfected with SARS-CoV-2 despite having advanced liver disease less frequently.

COVID-19 in hospitalized solid organ transplant recipients in a nationwide registry study.

OBJECTIVES: Underlying immunodeficiency has been associated with worse clinical presentation and increased mortality in patients with COVID-19. We evaluated the mortality of solid organ transplant (SOT) recipients (SOTR) hospitalized in Spain due to COVID-19. METHODS: Nationwide, retrospective, observational analysis of all adults hospitalized because of COVID-19 in Spain during 2020. Stratification was made according to SOT status. The National Registry of Hospital Discharges was used, using the International Classification of Diseases, 10th revision coding list. RESULTS: Of the 117,694 adults hospitalized during this period, 491 were SOTR: kidney 390 (79.4%), liver 59 (12%), lung 27 (5.5%), and heart 19 (3.9%). Overall, the mortality of SOTR was 13.8%. After adjustment for baseline characteristics, SOTR was not associated with higher mortality risk (odds ratio [OR] = 0.79, 95% confidence interval [CI] 0.60-1.03). However, lung transplantation was an independent factor related to mortality (OR = 3.26, 95% CI 1.33-7.43), while kidney, liver, and heart transplantation were not. Being a lung transplant recipient was the strongest prognostic factor in SOT patients (OR = 5.12, 95% CI 1.88-13.98). CONCLUSION: This nationwide study supports that the COVID-19 mortality rate in SOTR in Spain during 2020 did not differ from the general population, except for lung transplant recipients, who presented worse outcomes. Efforts should be focused on the optimal management of lung transplant recipients with COVID-19.

The slowdown of new infections by human retroviruses has reached a plateau in Spain.

The 2022 annual meeting of the HTLV & HIV-2 Spanish Network was held in Madrid on December 14. We summarize here the main information presented and discussed at the workshop and review time trends for human retroviral infections in Spain. As transmissible agents, infections by human retroviruses are of obligatory declaration. Until the end of 2022, the Spanish national registry had recorded 451 cases of HTLV-1, 821 of HTLV-2, and 416 of HIV-2. For HIV-1, estimates are of 150 000 people currently living with HIV-1 and 60 000 cumulative deaths due to AIDS. During year 2022, new diagnoses in Spain were of 22 for HTLV-1, 6 for HTLV-2, and 7 for HIV-2. The last updated figures for HIV-1 are from 2021 and counted 2786 new diagnoses. The slowdown in yearly infections for HIV-1 in Spain points out that new strategies are needed to achieve the United Nations 95-95-95 targets by 2025. For the remaining neglected human retroviral infections, their control might be pushed throughout four interventions: (1) expanding testing; (2) improving education and interventions aimed to reduce risk behaviors; (3) facilitating access to antiretrovirals as treatment and prevention, including further development of long-acting formulations; and (4) increasing vaccine research efforts. Spain is a 47 million population country in South Europe with strong migration flows from HTLV-1 endemic regions in Latin America and Sub-Saharan Africa. At this time universal HTLV screening has been implemented only in the transplantation setting, following the report of 5 cases of HTLV-associated myelopathy shortly after transplantation of organs from HTLV-1 positive donors. There are four target populations for expanding testing and unveiling asymptomatic carriers responsible for silent HTLV-1 transmissions: (1) migrants; (2) individuals with sexually transmitted infections; (3) pregnant women; and (4) blood donors.

Safety considerations in the management of hepatitis C and HIV co-infection.

INTRODUCTION: Both HCV and HIV are highly prevalent infections with current estimates of 57 and 38 million people infected worldwide, respectively. Oral antivirals can be curative for HCV and rescue HIV patients from disease progression. Dual therapy in coinfected patients requires expertise. AREAS COVERED: Four major issues challenge dual HCV and HIV treatment, including overlapping drug-related side effects, hepatitis B reactivation, immune reconstitution inflammatory syndromes (IRIS), and drug-drug interactions (DDI). A search was conducted in PubMed from January 2010 to March 2023. EXPERT OPINION: The advent of second-generation direct-acting antivirals (DDA) that depict higher antiviral potency, fewer side effects, pangenotypic activity and are co-formulated has expanded the indication of HCV therapy and particularly in HIV-coinfected individuals. Sequential initiation of antiretrovirals (ARV) followed by DAA is generally preferred to start dual treatment concomitantly. Close monitoring of rare episodes of HBV reactivation and IRIS is warranted. The most frequent DDI between DAA and ARV affect drug metabolism by CYP450 induction/inhibition, leading to abnormal drug exposures. Throughout this mechanism interact most HCV and HIV protease inhibitors and non-nucleoside polymerase inhibitors. Exposure to some HIV and HCV nucleos(t)ide analogues (e.g. tenofovir and sofosbuvir, respectively) is subject to induction/inhibition of drug transporters and requires special attention in patients with renal insufficiency.

Increased incidence of giant cell arteritis and associated stroke during the COVID-19 pandemic in Spain: A nation-wide population study.

INTRODUCTION: SARS-CoV-2 infection and COVID-19 vaccines might have increased the incidence of giant-cell arteritis (GCA) and the risk of associated stroke in Spain. METHODS: Retrospective nation-wide observational analysis of all adults hospitalized with GCA in Spain during 5 years (Jan-2016 and Dec-2021). The incidence and proportion of admissions with or because of GCA and GCA-associated stroke were compared between pre-pandemic (2016-2019) and pandemic (2020 and 2021) years. Sensitivity analyses were conducted for the different COVID-19 waves and vaccine timing schedules. RESULTS: A total of 17,268 hospital admissions in patients diagnosed with GCA were identified. During 2020 there were 79.3 and 8.1 per 100,000 admissions of GCA and GCA-associated stroke, respectively. During 2021 these figures were 80.8 and 7.7 per 100,00 admissions, respectively. As comparison, yearly admissions due to GCA and GCA-associated stroke were 72.4 and 5.7 per 100,00, respectively, during the pre-pandemic period (p < 0.05). Coincident with the third wave of COVID-19 (and first vaccine dosing), the rate of GCA-associated stroke admissions increased significantly (from 6.7 to 12%; p < 0.001). Likewise, there was an increase in GCA-associated stroke (6.6% vs 4.1%, p = 0.016) coincident with the third dose vaccination (booster) in patients older than 70 at the end of 2021. In multivariate analysis, only patients admitted during the third COVID-19 wave (and first vaccine dosing) (OR = 1.89, 95% CI 1.22-2.93), and during the third vaccination dosing in patients older than 70 (booster) (OR = 1.66, CI 1.11-2.49), presented a higher GCA-associated stroke risk than the same months of previous years after adjustment by age, sex, classical cardiovascular risk factors and COVID-19 diagnosis. CONCLUSIONS: The COVID-19 pandemic led to an increased incidence of GCA during 2020 and 2021. Moreover, the risk of associated stroke significantly risen accompanying times of COVID-19 vaccine dosing, hypothetically linked to an increased thrombotic risk of mRNA-SARS-CoV-2 vaccines. Hence, forthcoming vaccine policies and indications must weigh the risk of severe COVID-19 with the risk of flare or stroke in patients with GCA.

Susceptibility to hepatitis B virus infection in adults living in Spain.

BACKGROUND: A protective hepatitis B virus (HBV) vaccine has been available for four decades. Universal HBV vaccination of infants is recommended by the WHO since the 1990s. Furthermore, HBV immunization is advised for all adults with high-risk behaviours and no seroprotection. However, HBV vaccine coverage remains globally suboptimal. The advent of new more efficacious trivalent HBV vaccines has renewed the interest in HBV vaccination. At present, the extent of current HBV susceptibility in adults remains unknown in Spain. METHODS: HBV serological markers were assessed on a large and representative sample of adults in Spain, including blood donors and individuals belonging to high-risk groups. Serum HBsAg, anti-HBc and anti-HBs were tested in specimens collected during the last couple of years. RESULTS: From 13 859 consecutive adults tested at seven cities across the Spanish geography, overall 166 (1.2%) had positive HBsAg. Past HBV infection was recognized in 14% and prior vaccine immunization in 24%. Unexpectedly, 37% of blood donors and 63% of persons belonging to high-risk groups had no serum HBV markers and therefore were potentially HBV susceptible. CONCLUSION: Roughly 60% of adults living in Spain seem to be HBV susceptible. Waning immunity might be more common than expected. Hence, HBV serological testing should be performed at least once in all adults regardless of risk exposures. HBV vaccine full courses or boosters should be administered to all adults lacking serological evidence of HBV protection.

Bulevirtide in the Treatment of Hepatitis Delta: Drug Discovery, Clinical Development and Place in Therapy.

It has been ten years since the identification of NTCP as the cell surface receptor for HBV and HDV entry into hepatocytes. The search for molecules interfering with the binding of NTCP and HBV/HDV led to design bulevirtide (BLV). This large polypeptide mimics a region of the pre-S1 HBsAg and blocks viral entry by inhibitory competition. BLV was initially tested in cell cultures, animal models and more recently in Phase I-III human trials (called 'MYRS'). As monotherapy or in combination with peginterferon, BLV is well tolerated and exhibits potent antiviral activity. Plasma viremia significantly declines and/or becomes undetectable in more than 75% of patients treated for >24 weeks. However, serum HBsAg concentrations remain unchanged. No selection of BLV resistance in HBV/HDV has been reported in vivo to date. BLV is administered subcutaneously once daily at doses between 2 and 10 mg. BLV received conditional approval in Europe in 2020 to treat chronic hepatitis delta. The advent of peginterferon lambda or new specific anti-HDV antivirals (lonafarnib, etc.) will open the door for combination therapies with BLV. Since there is no stable reservoir for HDV-RNA within infected hepatocytes, viral clearance might be achieved using antivirals for a minimum timeframe. This is what happens in hepatitis C combining several antivirals, curing nearly all patients treated for 3 months. Clearance of HDV-RNA genomes may occur despite HBV persistence as cccDNA or chromosome integrated HBV-DNA within hepatocytes. This is supported by cases of HDV elimination using BLV despite persistence of serum HBsAg. Another path for HDV cure will derive from achieving HBsAg clearance, the goal of new promising anti-HBV gene therapies (bepirovirsen, etc.). In summary, the advent of BLV has triggered a renovated interest for antiviral therapy in hepatitis delta. We envision combination therapies that will lead to HDV cure in the near future.

Treatment of hepatitis delta and HIV infection.

Hepatitis delta virus (HDV) is a defective agent that only infects individuals with hepatitis B virus (HBV). Around 5-10% of chronic hepatitis B patients worldwide are superinfected with HDV, which means 15-25 million people. Hepatitis delta is the most severe of all chronic viral hepatitis, leading to cirrhosis, liver cancer and/or transplantation in most patients. Despite it, many HDV patients remain undiagnosed. The only treatment available until recently was peginterferon alfa, with poor results and significant side effects. The recent approval of bulevirtide, a lipopeptide that blocks HBV/HDV entry, has revolutionized the field. Another drug, lonafarnib, already approved to treat progeria, is expected to be available soon as HDV therapy. Since there is no cell reservoir for the HDV RNA genome, hypothetically viral clearance could be achieved if complete blocking of viral replication occurs for a minimum time frame. This is what happens in hepatitis C using direct-acting antivirals, with the achievement of cure in nearly all treated patients. We envision the cure of hepatitis delta using combination antiviral therapy. Given that sexual and parenteral transmission routes are the most frequent for the acquisition of HBV and HDV, shared with HIV infection and HBV/HDV and HIV coinfection. The clinical outcome of hepatitis delta is worst in the HIV setting, with more frequent liver complications. Since most persons infected with HIV are on regular health care follow-up, we propose that HIV-HDV patients should be prioritized for moving forward new and potentially curative treatments for hepatitis delta.