CRISPR-Mediated Viral Gene Knockout to Investigate Viral Evasion of Antiviral Innate Immunity.

The innate immune system relies on a variety of pathogen recognition receptors (PRRs) as the first line of defense against pathogenic invasions. Viruses have evolved multiple strategies to evade the host immune system through coevolution with hosts. The CRISPR-Cas system is an adaptive immune system in bacteria or archaea that defends against viral reinvasion by targeting nucleic acids for cleavage. Based on the characteristics of Cas proteins and their variants, the CRISPR-Cas system has been developed into a versatile gene-editing tool capable of gene knockout or knock-in operations to achieve genetic variations in organisms. It is now widely used in the study of viral immune evasion mechanisms. This chapter will introduce the use of the CRISPR-Cas9 system for editing herpes simplex virus 1 (HSV-1) genes to explore the mechanisms by which HSV-1 evades host innate immunity and the experimental procedures involved.

Short-form thymic stromal lymphopoietin (sfTSLP) restricts herpes simplex virus infection of human primary keratinocytes.

Eczema herpeticum (EH) is a disseminated severe herpes simplex virus type 1 (HSV-1) infection that mainly occurs in a subset of patients suffering from atopic dermatitis (AD). EH is complex and multifaceted, involving immunological changes, environmental influences, and genetic aberrations. Certain genetic variants of the thymic stromal lymphopoietin (TSLP) may predispose to develop severe HSV-1-induced eczema. Therefore, we investigated the impact of TSLP on HSV-1 infection. TSLP encodes for two distinct forms: a long-form (lfTSLP), primarily associated with type 2 immunity, and a short-form (sfTSLP) with anti-inflammatory and antimicrobial properties. While sfTSLP reduced HSV-1 infectibility in human primary keratinocytes (HPK), lfTSLP did not. In HPK treated with sfTSLP, HSV-1 gene expression, and replication decreased, while virion binding to cells and targeting of incoming capsids to the nucleus were not diminished compared to untreated cells. sfTSLP caused only minor changes in the expression of innate immunity cytokines, and its inhibition of HSV-1 infection did not require de novo protein synthesis. Time window experiments indicated a different antiviral mechanism than LL-37. sfTSLP showed the strongest antiviral effect when administered to HPK before or after inoculation with HSV-1, and outperformed the inhibitory potential of LL-37 under these conditions. Our data show that sfTSLP has antiviral functions and promotes repression of the HSV-1 infection in HPK.

Immunogenicity and protective efficacy of a recombinant lactococcus lactis vaccine against HSV-1 infection.

BACKGROUND: Herpes simplex virus type 1 (HSV-1) is a major cause of viral encephalitis, genital mucosal infections, and neonatal infections. Lactococcus lactis (L. lactis) has been proven to be an effective vehicle for delivering protein antigens and stimulating both mucosal and systemic immune responses. In this study, we constructed a recombinant L. lactis system expressing the protective antigen glycoprotein D (gD) of HSV-1. RESULTS: To improve the stability and persistence of antigen stimulation of the local mucosa, we inserted the immunologic adjuvant interleukin (IL)-2 and the Fc fragment of IgG into the expression system, and a recombinant L. lactis named NZ3900-gD-IL-2-Fc was constructed. By utilizing this recombinant L. lactis strain to elicit an immune response and evaluate the protective effect in mice, the recombinant L. lactis vaccine induced a significant increase in specific neutralizing antibodies, IgG, IgA, interferon-γ, and IL-4 levels in the serum of mice. Furthermore, in comparison to the mice in the control group, the vaccine also enhanced the proliferation levels of lymphocytes in response to gD. Moreover, recombinant L. lactis expressing gD significantly boosted nonspecific immune reactions in mice through the activation of immune-related genes. Furthermore, following the HSV-1 challenge of the murine lung mucosa, mice inoculated with the experimental vaccine exhibited less lung damage than control mice. CONCLUSION: Our study presents a novel method for constructing a recombinant vaccine using the food-grade, non-pathogenic, and non-commercial bacterium L. lactis. The findings indicate that this recombinant vaccine shows promise in preventing HSV-1 infection in mice.

Systematic review on molecular detection of congenital and neonatal infections caused by TORCH and SARS-CoV-2 in newborns' cerebrospinal fluid.

OBJECTIVE: To verify the use and identify advantages of molecular methods for congenital infections diagnosis in cerebrospinal fluid of neonates. DATA SOURCE: The review was registered in the International Prospective Register of Systematic Reviews (PROSPERO), under CRD42021274210. The literature search was performed in databases: PubMed, Virtual Health Library/ Latin American and Caribbean Center on Health Sciences Information (VHL/BIREME), Scopus, Web of Science, Excerpta Medica database (EMBASE), Cochrane, ProQuest, and EBSCOhost. The search was carried out from August to October 2021 and updated in December 2022, respecting the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The selection sequence was: 1) Duplicate title removal; 2) Examination of titles and abstracts; 3) Full-text retrieval of potentially relevant reports; and 4) Evaluation of the full text according to eligibility criteria by two independent authors. Inclusion criteria considered randomized and non-randomized control trials, longitudinal, cross-sectional, and peer-reviewed studies in humans, published in English, Spanish, Italian, and Portuguese, with newborns up to 28 days old who had congenital neuroinfections by toxoplasmosis, rubella, cytomegalovirus, herpes simplex (TORCH), and others such as Treponema pallidum, Zika, parvovirus B-19, varicella zoster, Epstein-Barr, and SARS-CoV2, diagnosed by polymerase chain reaction (PCR). Two evaluators extracted the following information: author, year of publication, nationality, subjects, study type, methods, results, and conclusion. DATA SYNTHESIS: The most studied pathogen was herpes simplex. Several articles reported only nonspecific initial symptoms, motivating the collection of cerebrospinal fluid and performing PCR for etiological investigation. CONCLUSIONS: Molecular methods are effective to detect pathogen genomes in cerebrospinal fluid, which can impact clinical evolution and neurological prognosis.

Analysis of HSV1/2 Infection Reveals an Association between HSV-2 Reactivation and Pregnancy.

The herpes simplex viruses consist of the strains, HSV-1 and HSV-2, which are prevalent worldwide and lack a definitive cure. We aimed to explore the specific characteristics of HSV 1 and 2 infections, such as differences between gender assigned at birth, age at infection, site of infection, comorbidities, and effect of pregnancy, through a data analysis. Between 2011 and 2018, the Israeli Central Virology Laboratory diagnosed 9189 samples using multiplexed real-time PCR. In addition, we extracted all of the medical data for 287 females hospitalized at the Sheba Medical Center with HSV-1 (161) or HSV-2 (126) genital infections. HSV-2 was almost absent in the orofacial samples from both genders, while in other lesion sites, HSV-2 was significantly more abundant in females than in males (p < 0.05,). HSV-2 was initially detected at puberty. In the hospitalized females' malignancies, both HSV-1 and HSV-2 were found with a non-significant difference. Simultaneously, pregnancies were more common in females who were HSV-2-positive compared with those who were HSV-1-positive (27.8% vs. 12.4%, respectively, p < 0.01). Primary infections occur more with HSV-1 than with HSV-2 (15.6% vs. 3.2%, respectively). Our findings demonstrate that genital HSV-2 infection episodes are more frequent during pregnancy, suggesting that pregnancy may serve as a risk factor for HSV-2 reactivation or infection.

Fas/FasL-Mediated Apoptosis and Inflammation Contribute to Recovery from HSV-2-Mediated Spinal Cord Infection.

Herpes simplex virus type 2 (HSV-2) is a sexually transmitted pathogen that causes a persistent infection in sensory ganglia. The infection manifests itself as genital herpes but in rare cases it can cause meningitis. In this study, we used a murine model of HSV-2 meningitis to show that Fas and FasL are induced within the CNS upon HSV-2 infection, both on resident microglia and astrocytes and on infiltrating monocytes and lymphocytes. Mice lacking Fas or FasL had a more severe disease development with significantly higher morbidity, mortality, and an overall higher CNS viral load. In parallel, these Fas/FasL-deficient mice showed a severely impaired infection-induced CNS inflammatory response with lower levels of infiltrating CD4+ T-cells, lower levels of Th1 cytokines and chemokines, and a shift in the balance between M1 and M2 microglia/monocytes. In vitro, we confirmed that Fas and FasL is required for the induction of leucocyte apoptosis, but also show that the Fas/FasL pathway is required for adequate cytokine and chemokine production by glial cells. In summary, our data show that the Fas/FasL cell death receptor pathway is an important defense mechanism in the spinal cord as it down-regulates HSV-2-induced inflammation while at the same time promoting adequate anti-viral immune responses against infection.

Presence of CD80 and Absence of LAT in Modulating Cellular Infiltration and HSV-1 Latency.

CD80 is the best-known costimulatory molecule for effective T cell functions. Many different reports have summarized the role of CD80 in HSV-1 and its functions in maintaining adaptive immunity, which is the main player in causing herpes stromal keratitis (HSK). To determine the effects of absence or overexpression of CD80 in HSV-1 infection, we infected CD80-/- and WT mice with a recombinant HSV-1 expressing murine CD80 (HSV-CD80) in place of the latency associated transcript (LAT). Parental dLAT2903 virus lacking LAT was used as a control. After infection, critical components of infection like virus replication, eye disease, early cellular infiltrates into the corneas and trigeminal ganglia (TG), latency-reactivation in the infected mice were determined. Our findings reveal that the absence of CD80 in the CD80-/- mice infected with both viruses did not affect the viral titers in the mice eyes or eye disease, but it played a significant role in critical components of HSV-induced immunopathology. The WT mice infected with dLAT2903 virus had significantly higher levels of latency compared with the CD80-/- mice infected with dLAT2903 virus, while levels of latency as determined by gB DNA expression were similar between the WT and CD80-/- mice infected with HSV-CD80 virus. In contrast to the differences in the levels of latency between the infected groups, the absence of CD80 expression in the CD80-/- mice or its overexpression by HSV-CD80 virus did not have any effect on the time of reactivation. Furthermore, the absence of CD80 expression contributed to more inflammation in the CD80-/--infected mice. Overall, this study suggests that in the absence of CD80, inflammation increases, latency is reduced, but reactivation is not affected. Altogether, our study suggests that reduced latency correlated with reduced levels of inflammatory molecules and blocking or reducing expression of CD80 could be used to mitigate the immune responses, therefore controlling HSV-induced infection.

HSV-2 Manipulates Autophagy through Interferon Pathway: A Strategy for Viral Survival.

Autophagy, an evolutionarily conserved cellular process, influences the regulation of viral infections. While the existing understanding indicates that Herpes Simplex Virus type 2 (HSV-2) maintains a basal level of autophagy to support its viral yield, the precise pathways governing the induction of autophagy during HSV-2 infection remain unknown. Therefore, this study aims to explore the role of type I interferons (IFN-I) in modulating autophagy during HSV-2 infection and to decode the associated signaling pathways. Our findings revealed an interplay wherein IFN-I regulates the autophagic response during HSV-2 infection. Additionally, we investigated the cellular pathways modulated during this complex process. Exploring the intricate network of signaling events involved in autophagy induction during HSV-2 infection holds promising therapeutic implications. Identifying these pathways advances our understanding of host-virus interactions and holds the foundation for developing targeted therapeutic strategies against HSV-2. The insight gained from this study provides a platform for exploring potential therapeutic targets to restrict HSV-2 infections, addressing a crucial need in antiviral research.

Toward the Eradication of Herpes Simplex Virus: Vaccination and Beyond.

Herpes simplex virus (HSV) has coevolved with Homo sapiens for over 100,000 years, maintaining a tenacious presence by establishing lifelong, incurable infections in over half the human population. As of 2024, an effective prophylactic or therapeutic vaccine for HSV remains elusive. In this review, we independently screened PubMed, EMBASE, Medline, and Google Scholar for clinically relevant articles on HSV vaccines. We identified 12 vaccines from our literature review and found promising candidates across various classes, including subunit vaccines, live vaccines, DNA vaccines, and mRNA vaccines. Notably, several vaccines-SL-V20, HF10, VC2, and mRNA-1608-have shown promising preclinical results, suggesting that an effective HSV vaccine may be within reach. Additionally, several other vaccines such as GEN-003 (a subunit vaccine from Genocea), HerpV (a subunit vaccine from Agenus), 0ΔNLS/RVx201 (a live-attenuated replication-competent vaccine from Rational Vaccines), HSV 529 (a replication-defective vaccine from Sanofi Pasteur), and COR-1 (a DNA-based vaccine from Anteris Technologies) have demonstrated potential in clinical trials. However, GEN-003 and HerpV have not advanced further despite promising results. Continued progress with these candidates brings us closer to a significant breakthrough in preventing and treating HSV infections.

A 4-Month-Old With Jaundice, Lethargy, and Emesis.

Acute liver failure is rare in the neonatal and infant population; however, when encountered, it requires timely diagnosis, management, and identification of the underlying etiology to provide the best clinical outcomes. Here, we present a case of new-onset liver failure in a 4-month-old infant. She had previously been diagnosed with neonatal mucocutaneous herpes simplex virus disease, but had been healthy in the interval, and was referred to our hospital for evaluation of possible need for liver transplantation because of a rapidly progressing pace of disease. In this diagnostic dilemma article, we review the case history and presentation and consider the differential diagnosis from the points of view of the primary and consultative teams. We then follow the clinical evolution of disease, identify a final diagnosis, and explore the short- and long-term management and health implications of the diagnosis. This case should be of interest to primary care providers, intensivists who care for neonates or infants, and specialists who encounter liver failure in their clinical practice.

Association of herpes simplex virus infection with hearing loss: a cross-sectional study using NHANES data from 2011 to 2012 and 2015 to 2016.

OBJECTIVES: To investigate the relationship between herpes simplex virus (HSV) and hearing loss using comprehensive population-based research. DESIGN: This cross-sectional study utilised data from the National Health and Nutrition Examination Survey (NHANES) to examine the relationship between HSV (types 1 and 2) and hearing loss. The final sample comprised 4608 participants aged 20-49 years. Weighted multivariate regression, subgroup and sensitivity analyses were employed for statistical evaluations. SETTING: Utilising the NHANES data, this cross-sectional study provides insights into the American population aged 20-49 years. PARTICIPANTS: The study includes 4608 participants from the NHANES 2011-2012 and 2015-2016 cycles, focusing on those with complete data on HSV infection and hearing assessment. INTERVENTIONS EXPOSURE: The study analyses the association between HSV (types 1 and 2) infection and hearing loss, using weighted multivariate regression for statistical evaluations. RESULTS: We observed an association between HSV-1 infection and an increased likelihood of hearing impairment (OR, 1.4 (95% CI 1.1 to 1.9)). A similar association was noted for those coinfected with HSV-1 and HSV-2 (OR, 1.6 (95% CI 1.1 to 2.3)). Similarly, higher grades of hearing loss and elevated pure-tone averages were more prevalent in these groups. Notably, the association between HSV-1 and hearing impairment was more pronounced in individuals aged 20-34 (OR, 2.1 (95% CI 1.4 to 3.3); P for interaction=0.020) and those with a body mass index (BMI) below 30 (OR, 1.8 (95% CI 1.1 to 2.8); P for interaction=0.028). CONCLUSIONS: Our findings suggest an association between HSV-1 infection or coinfections with HSV-1 and HSV-2 and the presence of hearing impairment. The association appears particularly pronounced among younger individuals and those with a lower BMI. Further prospective research is needed to explore the causal impact of HSV on auditory function.

Viral gene drive spread during herpes simplex virus 1 infection in mice.

Gene drives are genetic modifications designed to propagate efficiently through a population. Most applications rely on homologous recombination during sexual reproduction in diploid organisms such as insects, but we recently developed a gene drive in herpesviruses that relies on co-infection of cells by wild-type and engineered viruses. Here, we report on a viral gene drive against human herpes simplex virus 1 (HSV-1) and show that it propagates efficiently in cell culture and during HSV-1 infection in mice. We describe high levels of co-infection and gene drive-mediated recombination in neuronal tissues during herpes encephalitis as the infection progresses from the site of inoculation to the peripheral and central nervous systems. In addition, we show evidence that a superinfecting gene drive virus could recombine with wild-type viruses during latent infection. These findings indicate that HSV-1 achieves high rates of co-infection and recombination during viral infection, a phenomenon that is currently underappreciated. Overall, this study shows that a viral gene drive could spread in vivo during HSV-1 infection, paving the way toward therapeutic applications.

Seroprevalence and age-related susceptibility of TORCH infections in childbearing age women: A 5-year cross-sectional retrospective study and a literature review.

BACKGROUND: Serodiagnosis of TORCH infections should be performed in pre-pregnancy and reproductive-age women to prevent vertical transmission. Herein, we conducted a 5-year cross-sectional retrospective study in childbearing age women to provide prevalence data. Also, stratifying the cohort into three age groups, we identified those most susceptible to acute TORCH infections. METHODS: Between 2019 and 2023, serum samples from 2286 childbearing age women attending the "R. Dulbecco" University Hospital of Catanzaro were collected. Screening for TORCH pathogens, such as: Toxoplasma gondii (TOX), Cytomegalovirus (CMV), Rubella Virus (RUB), Parvovirus B19 (ParvoB19), Herpes Simplex Virus types 1 and 2 (HSV1, HSV2) and Treponema pallidum was carried out using serological tests. Chemiluminescent immunoassay was performed to detect TOX, CMV and ParvoB19 Immunoglobulin M (IgM) and Immunoglobulin G (IgG) antibodies, while Enzyme Linked Fluorescent Assay was performed to detect RUB IgM and IgG antibodies and CMV and TOX IgG Avidity. Enzyme Linked Immunosorbent Assay was performed to detect HSV1 IgG, HSV2 IgG, HSV1/2 IgM, T. pallidum total antibodies and RUB IgG Avidity. Binomial logistic regression models were developed to compare seroprevalence rates among different age groups. RESULTS: The highest immunological protection was observed for RUB infection (87 %), probably associated with vaccination practice, followed by HSV1 and CMV (82 % and 63 %). The 16-25 year age group results as the most susceptible to acute infections as demonstrated by odds of CMV IgM positivity (primary infection) which decreased with age. CONCLUSIONS: The TORCH serological screening program should be implemented in women before pregnancy to formulate strategies for serological screening of childbearing age women and guiding clinicians in making decisions.

HSV-1 immune escapes in microglia by down-regulating GM130 to inhibit TLR3-mediated innate immune responses.

BACKGROUND: To investigate the mechanism of Golgi matrix protein 130(GM130) regulating the antiviral immune response of TLR3 after herpes simplex virus type 1(HSV-1) infection of microglia cells. We explored the regulatory effects of berberine on the immune response mediated by GM130 and TLR3. METHODS: An in vitro model of HSV-1 infection was established by infecting BV2 cells with HSV-1. RESULTS: Compared to the uninfected group, the Golgi apparatus (GA) fragmentation and GM130 decreased after HSV-1 infection; TLR3 increased at 6 h and began to decrease at 12 h after HSV-1 infection; the secretion of interferon-beta(IFN-ß), tumour necrosis factor alpha(TNF-α), and interleukin-6(IL-6) increased after infection. Knockdown of GM130 aggravated fragmentation of the GA and caused TLR3 to further decrease, and the virus titer also increased significantly. GM130 knockdown inhibits the increase in TLR3 and inflammatory factors induced by TLR3 agonists and increases the viral titer. Overexpression of GM130 alleviated fragmentation of the GA induced by HSV-1, partially restored the levels of TLR3, and reduced viral titers. GM130 overexpression reversed the reduction in TLR3 and inflammatory cytokine levels induced by TLR3 inhibitors. Therefore, the decrease in GM130 levels caused by HSV-1 infection leads to increased viral replication by inhibiting TLR3-mediated innate immunity. Berberine can protect the GA and reverse the downregulation of GM130, as well as the downregulation of TLR3 and its downstream factors after HSV-1 infection, reducing the virus titer. CONCLUSIONS: In microglia, one mechanism of HSV-1 immune escape is disruption of the GM130/TLR3 pathway. Berberine protects the GA and enhances TLR3-mediated antiviral immune responses.

Antiviral potential of phenolic compounds against HSV-1: In-vitro study.

BACKGROUND: This in vitro study aimed to investigate the effect of several phenolic compounds, including doxorubicin, quercetin, and resveratrol, on HSV-1 infection. METHODS: The cytotoxicity of the drugs was assessed on Vero cells using the MTT assay. HSV-1 was treated with the drugs, and the supernatants were collected at various time points. TCID50% and qPCR tests were conducted on the supernatants to determine viral titration post-inoculation. RESULTS: The TCID50% assay showed significant changes in viral titration for acyclovir, doxorubicin, and quercetin at most concentrations (p-value < .05), while no significant changes were observed for resveratrol. The qPCR results demonstrated that drug-treated HSV-1 exhibited a significant reduction in DNA titers at various time points compared to non-treated HSV-1 infected Vero cells, except doxorubicin (0.2 µM) and acyclovir (5 µm). However, over time, DNA virus levels gradually increased in the drug-treated groups. Notably, at certain concentrations of doxorubicin and quercetin-treated groups, virus titer significantly declined, similar to acyclovir. CONCLUSIONS: Our findings suggest that quercetin at concentrations of 62 and 125 µM significantly reduced HSV-1 infectivity, as well as these two concentrations of quercetin showed a significant difference in virus reduction compared with acyclovir (10 µM) at certain time points. The anti-inflammatory properties of quercetin, in contrast to acyclovir, make it a potential candidate for anti HSV-1 treatment in life-threatening conditions such as Herpes encephalitis. Additionally, doxorubicin, an anticancer drug, showed meaningful inhibition of HSV-1 at non-toxic concentrations of 2 and 8 µM, suggesting its potential interference with HSV-1 in viral-oncolytic therapy in cancer treatment.

Israeli neonatal herpes simplex infection: Unique epidemiology and clinical profile.

To gather national level data on Israeli neonatal HSV (NHSV) infection and to evaluate the distinct clinical characteristics of NHSV and neonatal enteroviral meningitis (NEM). Israeli NHSV patients, hospitalized between January 2015 and April 2022 in 22 medical centers were assessed, together with NEM patients, hospitalized at Sheba Medical Center during the same period. NHSV demographic and clinical characteristics were documented and compared to those of NEM. Eighty-five NHSV (73% males) and 130 NEM (62% males) patients were included. The incidence of NHSV was 5.9/100 000 live births, the common phenotype and HSV type were SEM (53%) and HSV1 (91%), respectively. Horizontal transmission was suspected in 50% cases (of which 67% underwent a Jewish ritual circumcision with direct wound sucking, 33% had relatives with highly suspicious herpetic lesions). Compared with NEM, NHSV tends to present with rash (14% vs. 60%, p-value < 0.01) and seizures (0% vs. 6%, p-value 0.02), while fever, irritability and poor feeding appear more frequently in NEM (94% vs. 18%, p-value < 0.01; 37% vs. 1%, p-value < 0.01; 25% vs. 1%, p-value < 0.01 respectively). Of NEM patients, 28% were treated with acyclovir. Our results mark a decrease in the incidence rate of NHSV in Israel and a prominent mode of horizontal infection acquisition. We underscore the unique localized phenotype of NHSV, in contrast to enterovirus, which tends to cause a systemic disease with constitutional symptoms. These findings should be considered when evaluating the need for comprehensive empirical treatment for HSV in the context of neonatal fever, or according to a certain clinical presentation.

Characterization and Promising in vitro Antiherpetic Effect of Galactomannan from Delonix regia Seeds.

Herpes simplex virus (HSV) infections can occur throughout life, thereby allowing transmission to new hosts, with an impact on public health. Acyclovir remains the treatment of choice for these infections; however, an increase in resistant strains in recent years has been observed. In this study, the activity of a native Delonix regia galactomannan (NDr) against HSV-1 was investigated in vitro. NDr was characterized using infrared spectroscopy and NMR. Evaluation of cytotoxicity and the antiviral effect was determined, respectively, by MTT and plaque reduction assays. The NDr concentrations that inhibited cell viability (CC50) and viral infection (IC50) by 50% were above 2000 and 64 µg/mL, respectively. Thus, the polysaccharide showed a high selectivity index (> 31.25). When NDr was added at different stages of HSV-1 replication, a strong inhibitory effect was found by direct interaction with the virus (71-67%, virucidal effect) or previously with the cell, 6 h before infection (99.8-68.4%, prophylactic effect) at concentrations from 200 to 50 µg/mL. NDr showed similar effects in prophylactic 1 h (52%) and adsorption inhibition (55%) assays at 200 µg/mL. A reduction in the antiherpetic effect was observed after infection. These results suggest that NDr is effective in the early stages of HSV-1 infection and is a promising agent for controlling herpetic infections.

Helicase-primase inhibitors for the treatment of herpes simplex virus infections - patent evaluation of WO2023/225162 from Gilead Sciences Inc.

Helicase-primase is an interesting target for small-molecule therapy of herpes simplex virus (HSV) infections. With amenamevir already approved for varicella-zoster virus and herpes simplex in Japan and with pritelivir's granted breakthrough therapy designation for the treatment of acyclovir-resistant HSV infections in immunocompromised patients, the target has sparked interest in helicase-primase inhibitors (HPIs). Here, we analyze the first patent application from Gilead in this field, which pursued a me-too approach combining elements from an old Bayer together with a recent Medshine HPI application (which covers the Phaeno Therapeutics drug candidate HN0037). The asset was contributed to Assembly Biosciences, where it is under development as ABI-1179 at the investigational new drug (IND) enabling stage for high-recurrence genital herpes. A structure proposal for indolinoyl derivative ABI-1179 is presented, showing its potential opportunities and limitations compared to other HPIs.