Safety analysis of Oseltamivir and Baloxavir Marboxil after market approval: a pharmacovigilance study based on the FDA adverse event reporting system.

BACKGROUND AND OBJECTIVES: Amidst limited influenza treatment options, evaluating the safety of Oseltamivir and Baloxavir Marboxil is crucial, particularly given their comparable efficacy. This study investigates post-market safety profiles, exploring adverse events (AEs) and their drug associations to provide essential clinical references. METHODS: A meticulous analysis of FDA Adverse Event Reporting System (FAERS) data spanning the first quarter of 2004 to the fourth quarter of 2022 was conducted. Using data mining techniques like reporting odds ratio (ROR), proportional reporting ratio, Bayesian Confidence Propagation Neural Network, and Multiple Gamma Poisson Shrinkage, AEs related to Oseltamivir and Baloxavir Marboxil were examined. Venn analysis compared and selected specific AEs associated with each drug. RESULTS: Incorporating 15,104 Oseltamivir cases and 1,594 Baloxavir Marboxil cases, Wain analysis unveiled 21 common AEs across neurological, psychiatric, gastrointestinal, dermatological, respiratory, and infectious domains. Oseltamivir exhibited 221 significantly specific AEs, including appendicolith [ROR (95% CI), 459.53 (340.88 ∼ 619.47)], acne infantile [ROR (95% CI, 368.65 (118.89 ∼ 1143.09)], acute macular neuroretinopathy [ROR (95% CI), 294.92 (97.88 ∼ 888.64)], proctitis [ROR (95% CI), 245.74 (101.47 ∼ 595.31)], and Purpura senile [ROR (95% CI), 154.02 (81.96 ∼ 289.43)]. designated adverse events (DMEs) associated with Oseltamivir included fulminant hepatitis [ROR (95% CI), 12.12 (8.30-17.72), n=27], ventricular fibrillation [ROR (95% CI), 7.68 (6.01-9.83), n=64], toxic epidermal necrolysis [ROR (95% CI), 7.21 (5.74-9.05), n=75]. Baloxavir Marboxil exhibited 34 specific AEs, including Melaena [ROR (95% CI), 21.34 (14.15-32.18), n = 23], cystitis haemorrhagic [ROR (95% CI), 20.22 (7.57-54.00), n = 4], ileus paralytic [ROR (95% CI), 18.57 (5.98-57.71), n = 3], and haemorrhagic diathesis [ROR (95% CI), 16.86 (5.43-52.40)), n = 3]. DMEs associated with Baloxavir Marboxil included rhabdomyolysis [ROR (95% CI), 15.50 (10.53 ∼ 22.80), n = 26]. CONCLUSION: Monitoring fulminant hepatitis during Oseltamivir treatment, especially in patients with liver-related diseases, is crucial. Oseltamivir's potential to induce abnormal behavior, especially in adolescents, necessitates special attention. Baloxavir Marboxil, with lower hepatic toxicity, emerges as a potential alternative for patients with liver diseases. During Baloxavir Marboxil treatment, focused attention on the occurrence of rhabdomyolysis is advised, necessitating timely monitoring of relevant indicators for those with clinical manifestations. The comprehensive data aims to provide valuable insights for clinicians and healthcare practitioners, facilitating an understanding of the safety profiles of these influenza treatments in real-world scenarios.

Spleen tyrosine kinase inhibitor R406 has both antiviral and anti-inflammatory effects on severe influenza A infection.

Death due to severe influenza is usually a fatal complication of a dysregulated immune response more than the acute virulence of an infectious agent. Although spleen tyrosine kinase (SYK) as a critical immune signaling molecule and therapeutic target plays roles in airway inflammation and acute lung injury, the role of SYK in influenza virus infection is not clear. Here, we investigated the antiviral and anti-inflammatory effects of SYK inhibitor R406 on influenza infection through a coculture model of human alveolar epithelial (A549) and macrophage (THP-1) cell lines and mouse model. The results showed that R406 treatment increased the viability of A549 and decreased the pathogenicity and mortality of lethal influenza virus in mice with influenza A infection, decreased levels of intracellular signaling molecules under the condition of inflammation during influenza virus infection. Combination therapy with oseltamivir further ameliorated histopathological damage in the lungs of mice and further delayed the initial time to death compared with R406 treatment alone. This study demonstrated that phosphorylation of SYK is involved in the pathogenesis of influenza, and R406 has antiviral and anti-inflammatory effects on the treatment of the disease, which may be realized through multiple pathways, including the already reported SYK/STAT/IFNs-mediated antiviral pathway, as well as TNF-α/SYK- and SYK/Akt-based immunomodulation pathway.

Modular Biomimetic Strategy Enables Discovery and SAR Exploration of Oxime Macrocycles as Influenza A Virus (H1N1) Inhibitors.

Although vaccination remains the prevalent prophylactic means for controlling Influenza A virus (IAV) infections, novel structural antivirus small-molecule drugs with new mechanisms of action for treating IAV are highly desirable. Herein, we describe a modular biomimetic strategy to expeditiously achieve a new class of macrocycles featuring oxime, which might target the hemagglutinin (HA)-mediated IAV entry into the host cells. SAR analysis revealed that the size and linker of the macrocycles play an important role in improving potency. Particularly, as a 14-membered macrocyclic oxime, 37 exhibited potent inhibitory activity against IAV H1N1 with an EC50 value of 23 nM and low cytotoxicity, which alleviated cytopathic effects and protected cell survival obviously after H1N1 infection. Furthermore, 37 showed significant synergistic activity with neuraminidase inhibitor oseltamivir in vitro.

Comparative Effectiveness of Baloxavir Marboxil and Oseltamivir Treatment in Reducing Household Transmission of Influenza: A Post Hoc Analysis of the BLOCKSTONE Trial.

BACKGROUND: The transmission of influenza virus in households, especially by children, is a major route of infection. Prior studies suggest that timely antiviral treatment of ill cases may reduce infection in household contacts. The aim of the study was to compare the effects of oseltamivir (OTV) and baloxavir marboxil (BXM) treatment of index cases on the secondary attack rate (SAR) of influenza within household. METHODS: A post hoc analysis was done in BLOCKSTONE trial-a placebo-controlled, double-blinded post-exposure prophylaxis of BXM. Data were derived from the laboratory-confirmed index cases' household contacts who received placebo in the trial and also from household members who did not participate in the trial but completed illness questionnaires. To assess the SAR of household members, multivariate analyses adjusted for factors including age, vaccination status, and household size were performed and compared between contacts of index cases treated with BXM or OTV. RESULTS: In total, 185 index cases (116 treated with BXM and 69 treated with OTV) and 410 household contacts (201 from trial, 209 by questionnaire) were included. The Poisson regression modeling showed that the SAR in household contacts of index cases treated with BXM and OTV was 10.8% and 18.5%, respectively; the adjusted relative reduction in SAR was 41.8% (95% confidence interval: 1.0%-65.7%, p = 0.0456) greater with BXM than OTV. Similar reductions were found in contacts from the trial and those included by questionnaire. CONCLUSION: BXM treatment of index cases appeared to result in a greater reduction in secondary household transmission than OTV treatment.

In Vivo Immune-Modulatory Activity of Lefamulin in an Influenza Virus A (H1N1) Infection Model in Mice.

Lefamulin is a first-in-class systemic pleuromutilin antimicrobial and potent inhibitor of bacterial translation, and the most recent novel antimicrobial approved for the treatment of community-acquired pneumonia (CAP). It exhibits potent antibacterial activity against the most prevalent bacterial pathogens that cause typical and atypical pneumonia and other infectious diseases. Early studies indicate additional anti-inflammatory activity. In this study, we further investigated the immune-modulatory activity of lefamulin in the influenza A/H1N1 acute respiratory distress syndrome (ARDS) model in BALB/c mice. Comparators included azithromycin, an anti-inflammatory antimicrobial, and the antiviral oseltamivir. Lefamulin significantly decreased the total immune cell infiltration, specifically the neutrophils, inflammatory monocytes, CD4+ and CD8+ T-cells, NK cells, and B-cells into the lung by Day 6 at both doses tested compared to the untreated vehicle control group (placebo), whereas azithromycin and oseltamivir did not significantly affect the total immune cell counts at the tested dosing regimens. Bronchioalveolar lavage fluid concentrations of pro-inflammatory cytokines and chemokines including TNF-α, IL-6, IL-12p70, IL-17A, IFN-γ, and GM-CSF were significantly reduced, and MCP-1 concentrations were lowered (not significantly) by lefamulin at the clinically relevant 'low' dose on Day 3 when the viral load peaked. Similar effects were also observed for oseltamivir and azithromycin. Lefamulin also decreased the viral load (TCID50) by half a log10 by Day 6 and showed positive effects on the gross lung pathology and survival. Oseltamivir and lefamulin were efficacious in the suppression of the development of influenza-induced bronchi-interstitial pneumonia, whereas azithromycin did not show reduced pathology at the tested treatment regimen. The observed anti-inflammatory and immune-modulatory activity of lefamulin at the tested treatment regimens highlights a promising secondary pharmacological property of lefamulin. While these results require confirmation in a clinical trial, they indicate that lefamulin may provide an immune-modulatory activity beyond its proven potent antibacterial activity. This additional activity may benefit CAP patients and potentially prevent acute lung injury (ALI) and ARDS.

Assessing the impact of antiviral drugs commonly utilized during the COVID-19 pandemic on the embryonic development of Xenopus laevis.

The antiviral drugs favipiravir and oseltamivir are widely used to treat viral infections, including coronavirus 2019 (COVID-19), and their levels are expected to increase in the aquatic environment. In this study, the potential toxic and teratogenic effects of these drugs were evaluated using the frog embryo teratogenesis assay Xenopus (FETAX). In addition, glutathione S-transferase (GST), glutathione reductase (GR), catalase, carboxylesterase (CaE), and acetylcholinesterase (AChE) enzyme activities and malondialdehyde levels were measured as biochemical markers in embryos and tadpoles for comparative assessment of the sublethal effects of the test compounds. Prior to embryo exposure, drug concentrations in the exposure medium were measured with high-performance liquid chromatography. The 96-h median lethal concentration (LC50) was 137.9 and 32.3 mg/L for favipiravir and oseltamivir, respectively. The teratogenic index for favipiravir was 4.67. Both favipiravir and oseltamivir inhibited GR, CaE, and AChE activities in embryos, while favipiravir increased the GST and CaE activities in tadpoles. In conclusion, favipiravir, for which teratogenicity data are available in mammalian test organisms and human teratogenicity is controversial, inhibited Xenopus laevis embryo development and was teratogenic. In addition, sublethal concentrations of both drugs altered the biochemical responses in embryos and tadpoles, with differences between the developmental stages.

Antiviral influenza treatments and hemorrhage-related adverse events in the United States Food and Drug Administration Adverse Event Reporting System (FAERS) database.

STUDY OBJECTIVE: To determine whether there is a signal for gastrointestinal (GI) or intracranial (IC) hemorrhage associated with the use of antiviral medications for influenza in the US Food and Drug Administration (FDA) Adverse Event Reporting System (FAERS) database. DESIGN: Disproportionality analysis. DATA SOURCE: The FAERS database was searched using OpenVigil 2.1 to identify GI and IC hemorrhage events reported between 2004 and 2022. MEASUREMENTS: Antiviral medications for influenza included the following: oseltamivir, zanamivir, peramivir, and baloxavir marboxil. Hemorrhage events were identified using Standardized Medical Dictionary for Regulatory Activities (MedDRA) Queries for GI and IC hemorrhages. Reporting odds ratios (RORs) were calculated to compare the occurrence of GI and IC hemorrhage events between antiviral drugs for influenza and (i) all other medications and (ii) antibiotics. RORs were also calculated for each of the individual antiviral medications. MAIN RESULTS: A total of 245 cases of GI hemorrhage and 23 cases of IC hemorrhage were identified in association with four antivirals. In comparison with all other drugs, the RORs of GI hemorrhage for oseltamivir, zanamivir, peramivir, baloxavir, and all antivirals combined were 1.17, 0.62, 4.44, 2.53, and 1.22, respectively, indicating potential variations in GI hemorrhage risk among the antivirals. In contrast, in comparison with all other drugs, the RORs of IC hemorrhage for oseltamivir (0.44), zanamivir (0.16), baloxavir (0.44), and all antivirals combined (0.41) were less than 1.0 which is consistent with no elevated risk of IC hemorrhage. CONCLUSION: In this study, some signals for GI hemorrhage were observed, particularly for peramivir and baloxavir marboxil. Further investigation is warranted to better understand and evaluate the potential risks of GI hemorrhage associated with antiviral treatments for influenza.

Does oseltamivir prevent hospitalisation in people with influenza?

Overview of: Hanula R, Bortolussi-Courval É, Mendel A, et al. Evaluation of oseltamivir used to prevent hospitalization in outpatients with influenza: a systematic review and meta-analysis. JAMA Internal Medicine 2024;184:18-27.

Oseltamivir enhances 5-FU sensitivity in esophageal squamous carcinoma with high SPNS1.

Sphingolipid transporter 1 (SPNS1) is a significant differentially expressed gene (DEGs) in esophageal squamous cell carcinoma (ESCC). According to 3 pairs clinic cohorts, transcriptomic (155 pairs of ESCC samples and GSE53624, and proteomic data from PXD021701 including 124 ESCC samples) we found that SPNS1 was significantly higher in ESCC tissues compared to adjacent normal esophagus tissues. ESCC patients with high SPNS1 had a significantly poorer clinical prognosis than those with low SPNS1. Knockdown of SPNS1 significantly inhibited the proliferation, migration, and invasion abilities of ESCC cells, while promoting apoptosis. And overexpression of SPNS1 exhibited opposite functions. Furthermore, ESCC cells became more sensitive to 5-fluorouracil (5-FU) when SPNS1 was knocked down. Transcriptome sequencing revealed that NEU1 was one significant DEG affected by SPNS1 and positively correlated with SPNS1 expression. Oseltamivir phosphate (OP), one NEU1 inhibitor, markedly reversed 5-FU resistance, migration, and proliferation induced by high expression of SPNS1 both in vivo and in vitro. Our findings indicated that SPNS1 might promote the progression of ESCC by upregulating NEU1 expression and influencing chemotherapy sensitivity. These results provide new perceptions into potential therapeutic targets for ESCC treatment. The present study aimed to investigate the role and underlying mechanism of SPNS1 in ESCC.

Virological and clinical outcomes in outpatients treated with baloxavir or neuraminidase inhibitors for A(H3N2) influenza: A multicenter study of the 2022-2023 season.

While clinical trials have illuminated both the virological and clinical efficacy of baloxavir for influenza and post-treatment viral resistance, these aspects warrant further study in real-world settings. In response, we executed a prospective, observational study of the Japanese 2022-2023 influenza season. A cohort of 73 A(H3N2)-diagnosed outpatients-36 treated with baloxavir, 20 with oseltamivir, and 17 with other neuraminidase inhibitors (NAIs)-were analyzed. Viral samples were collected before and after administering an antiviral on days 1, 5, and 10, respectively. Cultured viruses were amplified using RT-PCR and sequenced to detect mutations. Fever and other symptoms were tracked via self-reporting diaries. In the baloxavir cohort, viral detection was 11.1% (4/36) and 0% (0/36) on day 5 and day 10, respectively. Two isolates from day 5 (5.6%, 2/36) manifested I38T/M-substitutions in the polymerase acidic protein (PA). For oseltamivir and other NAIs, viral detection rates were 60.0% (12/20) and 52.9% (9/17) on day 5, and 16.7% (3/18) and 6.3% (1/16) on day 10, respectively. No oseltamivir-resistant neuraminidase mutations were identified after treatment. Median fever durations for the baloxavir, oseltamivir, and other NAI cohorts were 27.0, 38.0, and 36.0 h, respectively, with no significant difference. Two patients harboring PA I38T/M-substitutions did not exhibit prolonged fever or other symptoms. These findings affirm baloxavir's virological and clinical effectiveness against A(H3N2) in the 2022-2023 season and suggest limited clinical influence of post-treatment resistance emergence.

Discovery of novel polyheterocyclic neuraminidase inhibitors with 1,3,4-oxadiazole thioetheramide as core backbone.

Inspired by our earlier findings regarding neuraminidase (NA) inhibitors interacting with 150-cavity or 430-cavity of NA, sixteen novel polyheterocyclic NA inhibitors with 1,3,4-oxadiazole thioetheramide as core backbone were designed and synthesized based on the lead compound ZINC13401480. Of the synthesized compounds, compound N5 targeting 150-cavity exerts the best inhibitory activity against the wild-type H5N1 NA, with IC50 value of 0.14 µM, which is superior to oseltamivir carboxylate (OSC) (IC50 = 0.31 µM). Compound N10 targeting 430-cavity exhibits the best activity against the H5N1-H274Y mutant NA. Although the activity of N10 is comparable to that of OSC for wild-type H5N1 inhibition, it is approximately 60-fold more potent than OSC against the H274Y mutant, suggesting that it is not easy for the virus to develop drug resistance and is attractive for drug development. N10 (EC50 = 0.11 µM) also exhibits excellent antiviral activity against H5N1, which is superior to the positive control OSC (EC50 = 1.47 µM). Molecular docking study shows that the occupation of aromatic fused rings and oxadiazole moiety at the active site and the extension of the substituted phenyl to the 150-cavity or 430-cavity make great contributions to the good potency of this series of polyheterocyclic NA inhibitors. Some advancements in the discovery of effective target-specific NA inhibitors in this study may offer some assistance in the development of more potent anti-influenza drugs.

Impact of the H274Y Substitution on N1, N4, N5, and N8 Neuraminidase Enzymatic Properties and Expression in Reverse Genetic Influenza A Viruses.

The H274Y substitution (N2 numbering) in neuraminidase (NA) N1 confers oseltamivir resistance to A(H1N1) influenza viruses. This resistance has been associated with reduced N1 expression using transfected cells, but the effect of this substitution on the enzymatic properties and on the expression of other group-1-NA subtypes is unknown. The aim of the present study was to evaluate the antiviral resistance, enzymatic properties, and expression of wild-type (WT) and H274Y-substituted NA for each group-1-NA. To this end, viruses with WT or H274Y-substituted NA (N1pdm09 or avian N4, N5 or N8) were generated by reverse genetics, and for each reverse-genetic virus, antiviral susceptibility, NA affinity (Km), and maximum velocity (Vm) were measured. The enzymatic properties were coupled with NA quantification on concentrated reverse genetic viruses using mass spectrometry. The H274Y-NA substitution resulted in highly reduced inhibition by oseltamivir and normal inhibition by zanamivir and laninamivir. This resistance was associated with a reduced affinity for MUNANA substrate and a conserved Vm in all viruses. NA quantification was not significantly different between viruses carrying WT or H274Y-N1, N4 or N8, but was lower for viruses carrying H274Y-N5 compared to those carrying a WT-N5. In conclusion, the H274Y-NA substitution of different group-1-NAs systematically reduced their affinity for MUNANA substrate without a significant impact on NA Vm. The impact of the H274Y-NA substitution on viral NA expression was different according to the studied NA.

An orally active entry inhibitor of influenza A viruses protects mice and synergizes with oseltamivir and baloxavir marboxil.

Seasonal or pandemic illness caused by influenza A viruses (IAVs) is a major public health concern due to the high morbidity and notable mortality. Although there are several approved drugs targeting different mechanisms, the emergence of drug resistance calls for new drug candidates that can be used alone or in combinations. Small-molecule IAV entry inhibitor, ING-1466, binds to hemagglutinin (HA) and blocks HA-mediated viral infection. Here, we show that this inhibitor demonstrates preventive and therapeutic effects in a mouse model of IAV with substantial improvement in the survival rate. When administered orally it elicits a therapeutic effect in mice, even after the well-established infection. Moreover, the combination of ING-1466 with oseltamivir phosphate or baloxavir marboxil enhances the therapeutic effect in a synergistic manner. Overall, ING-1466 has excellent oral bioavailability and in vitro absorption, distribution, metabolism, excretion, and toxicity profile, suggesting that it can be developed for monotherapy or combination therapy for the treatment of IAV infections.

Effectiveness of oseltamivir in reducing COVID-19-related in-hospital deaths: A pharmacoepidemiological study.

BACKGROUND: Oseltamivir is a low-cost antiviral agent that could support or complement treatment of COVID-19. This study assessed whether oseltamivir is effective in reducing COVID-19-related mortality. METHODS: This retrospective cohort study evaluated real-world data from a nationwide database of hospitalisation due to severe acute respiratory syndrome in Brazil. Propensity score matching was used to mimic a randomised controlled trial with 'oseltamivir' and 'no antivirals at all' as the intervention and control groups, respectively. RESULTS: A total of 21 480 and 268 486 patients admitted between February 2020 and January 2023 were included in the intervention and control groups, respectively. After matching, the odds ratio (OR) for death was 0.901 (95% confidence interval [CI] 0.873-0.930). The OR (95% CI) for death in patients who were admitted to the ICU, and on non-invasive or invasive ventilation was 0.868 (0.821-0.917), 0.935 (0.893-0.980), and 0.883 (0.814-0.958), respectively. CONCLUSIONS: Overall, the use of oseltamivir was associated with an attributable risk reduction of 2.50% (95% CI 1.77-3.29). Similar results were observed in patients who were admitted to the ICU, and on non-invasive or invasive ventilation. Oseltamivir is a low-cost potential antiviral treatment for COVID-19.

Clinical outcomes of baloxavir versus oseltamivir in immunocompromised patients.

BACKGROUND: Neuraminidase inhibitors, including oseltamivir, are the treatment standard for influenza. Baloxavir, a novel antiviral, demonstrated comparable outcomes to oseltamivir in outpatients with influenza. Baloxavir was equally effective as oseltamivir in a retrospective study of hospitalized patients with influenza at our institution. However, the efficacy of baloxavir in immunocompromised patients is unclear. METHODS: We conducted a retrospective cohort study of immunocompromised adult patients hospitalized with influenza A who received baloxavir from January 2019 to April 2019 or oseltamivir from January 2018 to April 2018. Demographic and clinical outcomes were assessed. Primary outcomes were time from antiviral initiation to resolution of hypoxia and fever. Secondary outcomes were length of stay (LOS), intensive care unit (ICU) care, ICU LOS, and 30-day mortality. RESULTS: Of 95 total patients, 52 received baloxavir and 43 received oseltamivir. Other than younger age (57.5 vs. 65; p = .035) and longer duration between vaccination and symptom onset (114 vs. 86 days; p = .001) in the baloxavir group, baseline characteristics did not differ. H1 was the predominant subtype in the baloxavir group (65.3%) versus H3 in the oseltamivir group (85.7%). When comparing baloxavir to oseltamivir, there was no significant difference in median time from antiviral initiation to resolution of hypoxia (59.9 vs. 42.5 h) and to resolution of fever (21.6 vs. 26.6 h). There were no differences in secondary outcomes. CONCLUSION: Baloxavir was not associated with longer time to resolution of hypoxia or fever in comparison to oseltamivir. Results must be taken in context of variations in seasonal influenza subtype and resistance rates.

A protectin DX (PDX) analog with in vitro activity against influenza A(H1N1) viruses.

Antiviral therapy based on neuraminidase (oseltamivir) or polymerase (baloxavir marboxil) inhibitors plays an important role in the management of influenza infections. However, the emergence of drug resistance and the uncontrolled inflammatory response are major limitations in the treatment of severe influenza disease. Protectins D1 (PD1) and DX (PDX), part of a family of pro-resolving mediators, have previously demonstrated anti-influenza activity as well as anti-inflammatory properties in various clinical contexts. Herein, we synthetized a series of simplified PDX analogs and assessed their in vitro antiviral activity against influenza A(H1N1) viruses, including oseltamivir- and baloxavir-resistant variants. In ST6GalI-MDCK cells, the PDX analog AN-137B reduced viral replication in a dose-dependent manner with IC50 values of 23.8 for A/Puerto Rico/8/1934 (H1N1) and between 32.6 and 36.7 µM for susceptible and resistant A(H1N1)pdm09 viruses. In MTS-based cell viability experiments, AN-137B showed a 50% cellular cytotoxicity (CC50 ) of 638.7 µM with a resulting selectivity index of 26.8. Of greater importance, the combination of AN-137B with oseltamivir or baloxavir resulted in synergistic and additive in vitro effects, respectively. Treatment of lipopolysaccharide (LPS)-stimulated macrophages with AN-137B resulted in a decrease of iNOS activity as shown by the reduction of nitrite production, suggesting an anti-inflammatory effect. In conclusion, our results indicate that the protectin analog AN-137B constitutes an interesting therapeutic modality against influenza A virus, warranting further evaluation in animal models.

Clinical and inflammatory response to antiviral treatments in dogs with parvoviral enteritis.

BACKGROUND: Canine parvoviral enteritis (CPE) is a fatal disease worldwide. The treatment of CPE is based mainly on supportive and symptomatic treatment. Antiviral addition to the treatment may result in a higher survival. OBJECTIVES: This study evaluated the effects of antiviral treatments with a standardized treatment (ST) on the clinical and inflammatory response of dogs with naturally occurring CPE. METHODS: Twenty-eight dogs with CPE caused by canine parvovirus type 2 were divided randomly into treatment groups. The ST group received fluid, antibiotic, antiemetic, and deworming treatments. The antiviral treatment groups received the same ST with an additional antiviral drug, recombinant feline interferon omega (rFeIFN-ω), oseltamivir (OSEL) or famciclovir (FAM). RESULTS: Compared to the healthy control, the tumor necrosis factor-α, interleukin-1ß, interferon (IFN)-α, IFN-γ, haptoglobin, and C-reactive protein values were high (p < 0.05) on day zero. At presentation, mild lymphopenia, neutropenia, and a high neutrophil to lymphocyte (LYM) ratio (NLR) were also observed. Adding rFeIFN-ω to the ST produced the best improvement in the clinical score with a decreased NLR, while leucocytes remained low and inflammatory markers stayed high on day three. The survival rates of the groups were 85.7% in ST+IFN, 71.4% in ST+OSEL, 71.4% in ST+FAM, and 57.1% in ST groups on day seven. CONCLUSIONS: Antiviral drugs may be valuable in treating CPE to improve the clinical signs and survival. In addition, the decrease in NLR in favor of LYM may be an indicator of the early prognosis before the improvement of leukocytes, cytokines, and acute phase proteins in CPE.

Structural Studies of Inhibitors with Clinically Relevant Influenza Endonuclease Variants.

Vital to the treatment of influenza is the use of antivirals such as Oseltamivir (Tamiflu) and Zanamivir (Relenza); however, antiviral resistance is becoming an increasing problem for these therapeutics. The RNA-dependent RNA polymerase acidic N-terminal (PAN) endonuclease, a critical component of influenza viral replication machinery, is an antiviral target that was recently validated with the approval of Baloxavir Marboxil (BXM). Despite its clinical success, BXM has demonstrated susceptibility to resistance mutations, specifically the I38T, E23K, and A36 V mutants of PAN. To better understand the effects of these mutations on BXM resistance and improve the design of more robust therapeutics, this study examines key differences in protein-inhibitor interactions with two inhibitors and the I38T, E23K, and A36 V mutants. Differences in inhibitor binding were evaluated by measuring changes in binding to PAN using two biophysical methods. The binding mode of two distinct inhibitors was determined crystallographically with both wild-type and mutant forms of PAN. Collectively, these studies give some insight into the mechanism of antiviral resistance of these mutants.