Griffithsin (GRFT), a lectin derived from the red algae Griffithsia, is known as an antiviral agent that binds to high-mannose glycans on viral envelope glycoproteins (GPs). In this study, we evaluated the antiviral activity of GRFT against Ebola virus (EBOV), Marburg virus (MARV), Lassa virus (LASV), Lujo virus (LUJV), and Crimean-Congo hemorrhagic fever virus (CCHFV), all of which cause severe and often fatal hemorrhagic fevers in humans. GRFT effectively blocked the entry of these viruses into cells, with stronger inhibition observed against LASV, LUJV, and CCHFV than against EBOV and MARV. This inhibitory effect depended on the lectin activity of GRFT, as its mutant lacking glycan-binding function completely lost the ability to inhibit the entry of these viruses into cells. We found that GRFT induced aggregation of virus-like particles (VLPs) derived from EBOV and MARV, whereas this activity was not observed with LASV- and LUJV-derived VLPs. Most of the escape mutants of LASV and LUJV GPs exhibited amino acid substitutions that likely disrupted GRFT binding by removing glycosylation sites at positions 79 and 73, respectively. Interestingly, other substitutions close to these positions, although unrelated to glycosylation, also contributed to reduced inhibitory activity of GRFT, suggesting a unique recognition mode in which both sugar chains and adjacent amino acid residues constitute the binding site structure for GRFT. Overall, our results provide insights into mechanisms underlying the antiviral effects of GRFT and highlight lectin-related activities as a key feature for broad-spectrum antiviral agents targeting highly glycosylated envelope GPs. IMPORTANCE:Emerging and re-emerging infectious diseases, including viral hemorrhagic fevers, pose a major global health threat due to their potential for widespread outbreaks. Currently, treatment options for such diseases are limited and often ineffective against newly emerging viruses. Here, we demonstrate that Griffithsin (GRFT), a naturally derived lectin from red algae, inhibits the entry of multiple hemorrhagic fever viruses into host cells. By blocking key processes of the viral entry mediated by envelope glycoproteins, lectins such as GRFT can exhibit broad antiviral activity that could potentially overcome the limitations of existing treatments against emerging viruses. Our findings emphasize that targeting sugar chains and adjacent structures on viral glycoproteins with GRFT could provide a therapeutic strategy against diverse viral species. Such an approach is particularly valuable for newly emerging viruses for which specific countermeasures have not yet been established.

Crimean-Congo hemorrhagic fever virus (CCHFV) causes a severe, sometimes fatal hemorrhagic fever (CCHF) in humans. Currently, there are no approved therapies against CCHF. In this study we used the recombinant vesicular stomatitis virus (VSV) platform to generate live-attenuated recombinant CCHF vaccine candidates expressing the CCHFV nucleoprotein (NP) and glycoprotein precursor (GPC). As one approach, we utilized the established VSV expressing the full-length Ebola virus glycoprotein (VSV-EBOV) or a truncated version of the EBOV glycoprotein and added the CCHFV-NP (VSV-CCHFnp1 or VSV-CCHFnp2, respectively). Additionally, we prepared a vaccine candidate, VSV-CCHFgpc, in which the VSV glycoprotein was replaced with the CCHFV-GPC. Vaccine constructs induced CCHFV-specific IgG antibodies comprising largely IgG2c subclass. Only, the VSV-CCHFgpc vaccine candidate induced significant T cell immune responses directed against epitopes in the CCHFV-NSm and Gc proteins. Efficacy of the vaccine candidates was evaluated using a prime-only approach in a transiently immune-suppressed mouse model. Animals vaccinated with VSV-CCHFnp2 succumbed to lethal CCHFV challenge, while the VSV-CCHFgpc vaccine candidate afforded partial protection. In contrast, vaccination with VSV-CCHFnp1 uniformly protected animals against death. Our results demonstrate the promise of VSV-CCHFnp1 as a vaccine candidate for CCHFV and warrant continued development.

Since early 2022, highly pathogenic avian influenza (HPAI) H5N1 virus infections have been reported in wild aquatic birds and poultry throughout the USA with spillover into several mammalian species1-6. In March 2024, HPAIV H5N1 clade 2.3.4.4b was first detected in dairy cows in Texas, USA, and continues to circulate on dairy farms in many states7,8. Milk production and quality are diminished in infected dairy cows, with high virus titres in milk raising concerns of exposure to mammals including humans through consumption9-12. Here we investigated routes of infection with bovine HPAIV H5N1 clade 2.3.4.4b in cynomolgus macaques, a surrogate model for human infection13. We show that intranasal or intratracheal inoculation of macaques could cause systemic infection resulting in mild and severe respiratory disease, respectively. By contrast, infection by the orogastric route resulted in limited infection and seroconversion of macaques that remained subclinical.

The ongoing circulation of influenza A H5N1 in the United States has raised concerns of a pandemic caused by highly pathogenic avian influenza. Although the United States has stockpiled and is prepared to produce millions of vaccine doses to address an H5N1 pandemic, currently circulating H5N1 viruses contain multiple mutations within the immunodominant head domain of hemagglutinin (HA) compared to the antigens used in stockpiled vaccines. It is unclear if these stockpiled vaccines will need to be updated to match the contemporary H5N1 strains. Here we show that a replicating RNA vaccine expressing the HA of an H5N1 isolated from a US dairy cow confers complete protection against homologous lethal challenge in mice. A repRNA encoding the HA of a clade 1 H5 from 2004 (A/Vietnam/1203/2004) as utilized by some stockpiled vaccines, confers only partial protection. Our data highlight the utility of nucleic acid vaccines to be rapidly updated to match emergent viruses of concern while demonstrating that contemporary bovine H5N1 viruses can evade immunity elicited by historical HA antigens.

BACKGROUND:Crimean-Congo Haemorrhagic Fever Virus is a tick-borne bunyavirus prevalent across Asia, Africa, the Middle East, and Europe. The virus causes a non-specific febrile illness which may develop into severe haemorrhagic disease. To date, there are no widely approved therapeutics. Recently, we reported an alphavirus-based replicon RNA vaccine which expresses the CCHFV nucleoprotein (repNP) or glycoprotein precursor (repGPC) and is protective against lethal disease in mice.METHODS:Here, we evaluated engineered GPC constructs to find the minimal enhancing epitope of repGPC and test two RNA vaccine approaches to express multiple antigens in vivo to optimize protective efficacy of our repRNA.FINDINGS:Vaccination with repNP and a construct expressing just the Gc antigen (repGc-FL) resulted in equivalent immunogenicity and protective efficacy compared to original repNP + repGPC vaccination. This vaccine was protective when prepared in either of two vaccine approaches, a mixed synthesis reaction producing two RNAs in a single tube and a single RNA expressing two antigens.INTERPRETATION:Overall, our data illustrate two vaccine approaches to deliver two antigens in a single immunization. Both approaches induced protective immune responses against CCHFV in this model. These approaches support their continued development for this and future vaccine candidates for CCHFV and other vaccines where inclusion of multiple antigens would be optimal.FUNDING:This work was supported by the Intramural Research Program, NIAID/NIH, HDT Bio and MCDC Grant #MCDC2204-011.

The highly pathogenic avian influenza (HPAI) A(H5N1) clade 2.3.4.4b viruses, responsible for the current outbreak in dairy cows in the United States, pose a significant animal and public health threat. In this study, we compared disease progression and pathology of three recent clade 2.3.4.4b isolates derived from a cow, mountain lion, and mink to a human HPAI A(H5N1) isolate from Vietnam in mice. Inoculation of C57BL/6J and BALB/c mice with all four HPAI A(H5N1) isolates resulted in comparable levels of virus replication in the lung inducing severe respiratory disease. C57BL/6J mice infected with the bovine isolate also developed high virus titers in the brain, resulting in a significant pro-inflammatory cytokine response and neurologic disease. Our findings suggest the recent bovine isolate possesses enhanced respiratory and neuroinvasive/neurovirulent properties causing fatal respiratory and neurologic disease in C57BL/6J mice. ### Competing Interest Statement The authors have declared no competing interest.

Crimean-Congo hemorrhagic fever virus (CCHFV) causes Crimean-Congo hemorrhagic fever (CCHF) in humans with high morbidity and mortality. Currently, there is neither an approved antiviral drug nor a vaccine against CCHFV. In this study, we describe a lethal model of CCHFV infection using a mouse-adapted strain of CCHFV (MA-CCHFV) in adult wild-type male mice. Infected mice developed high viral loads, tissue pathology, and inflammatory immune responses before ultimately succumbing to the infection. We used the model to evaluate the protective efficacy of nucleoside analogs monulpiravir, favipiravir, ribavirin, the antibiotic tigecycline and the corticosteroids dexamethasone and methylprednisolone against lethal CCHFV infection. Tigecycline, monulpiravir and the corticosteroids failed to protect mice from lethal MA-CCHFV infection. In contrast, favipiravir and ribavirin protected animals from clinical disease and death even when treatment was delayed. Despite demonstrating uniform protection, CCHFV RNA persisted in survivors treated with favipiravir and ribavirin. Nevertheless, the study demonstrated the anti-CCHFV efficacy of favipiravir and ribavirin in a model with intact innate immunity and establishes this model for continued development of CCHFV countermeasures.

Aim: The aim of this study was to investigate the utility of serological tests for the diagnosis of COVID-19 during the first week of symptom onset in patients confirmed with the real-time RT-PCR. Materials & methods: A systematic review and meta-analysis of 58 publications were performed using data obtained from Academic Search Ultimate, Africa-wide, Scopus, Web of Science and MEDLINE. Results: We found that the highest pooled sensitivities were obtained with ELISA IgM-IgG and chemiluminescence immunoassay IgM tests. Conclusion: Serological tests have low sensitivity within the first week of symptom onset and cannot replace nucleic acid amplification tests. However, serological assays can be used to support nucleic acid amplification tests.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread across the globe at unprecedented speed and is showing no signs of slowing down. The outbreak of coronavirus disease 2019 (COVID-19) has led to significant health burden in infected patients especially in those with underlying comorbidities. The aim of this study was to evaluate the correlation between comorbidities and their role in the exacerbation of disease in COVID-19 patients leading to fatal outcomes. A systematic review was conducted using data from MEDLINE, Scopus, Web of Science, and EMBASE databases published from 1 December 2019 to 15 September 2020. Fifty-three articles were included in the systematic review. Of those 53 articles, 8 articles were eligible for meta-analysis. Hypertension, obesity, and diabetes mellitus were identified to be the most prevalent comorbidities in COVID-19 patients. Our meta-analysis showed that cancer, chronic kidney diseases, diabetes mellitus, and hypertension were independently associated with mortality in COVID-19 patients. Chronic kidney disease was statistically the most prominent comorbidity leading to death. However, despite having high prevalence, obesity was not associated with mortality in COVID-19 patients. IMPORTANCE COVID-19 has plagued the world since it was first identified in December 2019. Previous systematic reviews and meta-analysis were limited by various factors such as the usage of non-peer reviewed data and were also limited by the lack of clinical data on a global scale. Comorbidities are frequently cited as risk factors for severe COVID-19 outcomes. However, the degree to which specific comorbidities impact the disease is debatable. Our study selection involves a global reach and covers all comorbidities that were reported to be involved in the exacerbation of COVID-19 leading to fatal outcomes, which allows us to identify the specific comorbidities that have higher risk in patients. The study highlights COVID-19 high-risk groups. However, further research should focus on the status of comorbidities and prognosis in COVID-19 patients.

Crimean–Congo hemorrhagic fever virus (CCHFV) infrequently causes hemorrhagic fever in humans with a case fatality rate of 30%. Currently, there is neither an internationally approved antiviral drug nor a vaccine against the virus. A replicon based on the Sindbis virus vector encoding the complete open reading frame of a CCHFV nucleoprotein from a South African isolate was prepared and investigated as a possible candidate vaccine. The transcription of CCHFV RNA and recombinant protein production by the replicon were characterized in transfected baby hamster kidney cells. A replicon encoding CCHFV nucleoprotein inserted in plasmid DNA, pSinCCHF-52S, directed transcription of CCHFV RNA in the transfected cells. NIH-III heterozygous mice immunized with pSinCCHF-52S generated CCHFV IgG specific antibodies with notably higher levels of IgG2a compared to IgG1. Splenocytes from mice immunized with pSinCCHF-52S secreted IFN-γ and IL-2, low levels of IL-6 or IL-10, and no IL-4. No specific cytokine production was registered in splenocytes of mock-immunized mice (p < 0.05). Thus, our study demonstrated the expression of CCHFV nucleoprotein by a Sindbis virus vector and its immunogenicity in mice. The spectrum of cytokine production and antibody profile indicated predominantly Th1-type of an anti-CCHFV immune response. Further studies in CCHFV-susceptible animals are necessary to determine whether the induced immune response is protective.

Crimean-Congo hemorrhagic fever (CCHF) is a severe human disease with mortality rates of up to 30%. The disease is widespread in Africa, Asia, the Middle East and Eastern Europe. The last few years have seen disease emergence in Spain for the first time and disease re-emergence in other regions of the world after periods of inactivity. Factors, such as climate change, movement of infected ticks, animals, and changes in human activity, are likely to broaden endemic foci. There are therefore concerns that CCHF might emerge in currently nonendemic regions. The absence of approved vaccines or therapies heightens these concerns; thus Crimean-Congo hemorrhagic fever virus (CCHFV) is listed by the World Health Organization as a priority organism. However, the current sporadic nature of CCHF cases may call for targeted vaccination of risk groups as opposed to mass vaccinations. CCHF vaccine development has accelerated in recent years, partly because of the discovery of CCHF animal models. In this review, we discuss CCHF risk groups who are most likely to benefit from vaccine development, the merits and demerits of available CCHF animal models, and the various approaches which have been explored for CCHF vaccine development. Lastly, we present concluding remarks and research areas which can be further explored to enhance the available CCHFV vaccine data.