Knowledge, perceptions, and exposure to bats in communities living around bat roosts in Bundibugyo district, Uganda: implications for viral haemorrhagic fever prevention and control

BACKGROUND

Bats are a reservoir for many viruses causing haemorrhagic fevers. Proximity to bats is a risk factor for virus spillover to animals and humans. We conducted this study to assess knowledge, perceptions, and exposure to bats in communities living near bat roosts in Bundibugyo District, Uganda.

METHODS

A cross-sectional study using mixed methods with both quantitative and qualitative data was conducted between September and December 2022. Participants for the quantitative data (survey) (n = 384) resided near bat caves and/or roost sites and were selected using multistage random sampling. The survey investigated participants' prior exposure to bats, as well as knowledge and perceptions of bat exposure. Logistic regression was used to determine factors associated with bat exposure. Participants for the qualitative data (focus group discussions) (n = 10, 6-8 participants each) were purposely selected based on engagement in guano mining, hunting, and farming activities. Perceived risk associated with bat-related activities were identified and ranked in the focus group discussions using participatory epidemiology tools.

RESULTS

In total, (214/384, 55.7%) had a history of bat exposure and (208/384, 54.2%) had poor knowledge of risk factors associated with bat exposure. Increased exposure to bats was associated with being male (OR = 1.6; 95% CI: 1.0, 2.4 p-value = 0.038), staying in urban areas (OR = 1.9; p-value = 0.010), hunting (OR = 10.9; p-value = 0.024), and positive perception to bat guano being safe as fertiliser (OR = 2.5; p-value = 0.045). During the proportional piling process, a total of 7 risk factors were identified by 10 groups with hunting during an outbreak and consumption of bats being the most frequently identified. Overall, there was a strong statistical agreement in the ranking across the 10 focus groups (W = 0.52; p < 0.01; n = 10). Based on the provided data, the adjusted odds ratio of 0.7 for the good measures (p-value = 0.112), suggests a potential protective effect on the risk of bat exposure.

CONCLUSION

Communities living around bat roosts frequently come into contact with bats, yet there is inadequate awareness regarding the behaviors that can lead to the transmission of bat- borne diseases to humans. It is essential to undertake educational initiatives and preventive measures to minimise the risks of bat-related infections. The need for targeted health communication and education efforts to address these knowledge gaps and promote an accurate understanding of bats and disease transmission. Understanding of diseases associated with bats will minimize bat-related health risks especially in communities engaged in wildlife hunting.

Characterization of antibodies targeting severe fever with thrombocytopenia syndrome virus glycoprotein Gc

Severe fever with thrombocytopenia syndrome (SFTS) is a hemorrhagic fever caused by SFTS virus (SFTSV), which is primarily found in East Asian countries. Despite its high mortality rate and increasing incidence, no vaccines or therapeutics have yet been approved for use against SFTS. Antibody drugs have shown promise in treating lethal infectious diseases that currently have no established treatments. In the case of SFTS, however, only a limited amount of research has been done on SFTSV-neutralizing antibodies targeting the transmembrane proteins Gn and Gc, which play critical roles in viral infection. This study focuses on the production and characterization of antibodies targeting the SFTSV Gc protein. Monoclonal antibodies against Gc were generated through immunization of mice, and their antiviral activity was evaluated. Three out of four anti-Gc antibody clones from this study demonstrated dose-dependent SFTSV neutralization activity, two of which exhibited a synergistic effect on the neutralization activity of the anti-Gn antibody clone Mab4-5. Further studies are necessary to identify key sites on the SFTSV glycoprotein and to develop novel agents as well as antibodies with diverse mechanisms of action against SFTSV.

Plasmid-Based Lassa Virus Reverse Genetics

Several mammarenaviruses cause hemorrhagic fever (HF) disease in humans and pose a significant public health problem in their endemic regions. The Old World (OW) mammarenavirus Lassa virus (LASV) is estimated to infect several hundred thousand people yearly in West Africa, resulting in high numbers of Lassa fever (LF) cases, a disease associated with high morbidity and mortality. No licensed vaccines are available to combat LASV infection, and anti-LASV drug therapy is limited to the off-label use of ribavirin whose efficacy remains controversial. The development of reverse genetics approaches has provided investigators with a powerful approach for the investigation of the molecular, cell biology and pathogenesis of mammarenaviruses. The use of cell-based minigenome systems has allowed examining the cis- and trans-acting factors involved in viral genome replication and gene transcription, assembly, and budding, which has facilitated the identification of several anti-mammarenavirus candidate drugs. Likewise, it is possible now to rescue infectious recombinant mammarenaviruses from cloned cDNAs containing predetermined mutations in their genomes to investigate virus-host interactions and mechanisms of viral pathogenesis. Reverse genetics have also allowed the generation of mammarenaviruses expressing foreign genes to facilitate virus detection, to identify antiviral drugs, and to generate live-attenuated vaccine (LAV) candidates. Likewise, reverse genetics techniques have allowed the generation of single-cycle infectious, reporter-expressing mammarenaviruses to study some aspects of the biology of HF-causing human mammarenavirus without the need of high security biocontainment laboratories. In this chapter, we describe the experimental procedures to generate recombinant (r)LASV using state-of-the-art plasmid-based reverse genetics.

Natural history of Ebola virus disease in rhesus monkeys shows viral variant emergence dynamics and tissue-specific host responses

Ebola virus (EBOV) causes Ebola virus disease (EVD), marked by severe hemorrhagic fever; however, the mechanisms underlying the disease remain unclear. To assess the molecular basis of EVD across time, we performed RNA sequencing on 17 tissues from a natural history study of 21 rhesus monkeys, developing new methods to characterize host-pathogen dynamics. We identified alterations in host gene expression with previously unknown tissue-specific changes, including downregulation of genes related to tissue connectivity. EBOV was widely disseminated throughout the body; using a new, broadly applicable deconvolution method, we found that viral load correlated with increased monocyte presence. Patterns of viral variation between tissues differentiated primary infections from compartmentalized infections, and several variants impacted viral fitness in a EBOV/Kikwit minigenome system, suggesting that functionally significant variants can emerge during early infection. This comprehensive portrait of host-pathogen dynamics in EVD illuminates new features of pathogenesis and establishes resources to study other emerging pathogens.

Universal primers for rift valley fever virus whole-genome sequencing

Rift Valley fever (RVF) is a mosquito-borne zoonotic disease causing acute hemorrhagic fever. Accurate identification of mutations and phylogenetic characterization of RVF virus (RVFV) require whole-genome analysis. Universal primers to amplify the entire RVFV genome from clinical samples with low copy numbers are currently unavailable. Thus, we aimed to develop universal primers applicable for all known RVFV strains. Based on the genome sequences available from public databases, we designed eight pairs of universal PCR primers covering the entire RVFV genome. To evaluate primer universality, four RVFV strains (ZH548, Kenya 56 (IB8), BIME-01, and Lunyo), encompassing viral phylogenetic diversity, were chosen. The nucleic acids of the test strains were chemically synthesized or extracted via cell culture. These RNAs were evaluated using the PCR primers, resulting in successful amplification with expected sizes (0.8-1.7 kb). Sequencing confirmed that the products covered the entire genome of the RVFV strains tested. Primer specificity was confirmed via in silico comparison against all non-redundant nucleotide sequences using the BLASTn alignment tool in the NCBI database. To assess the clinical applicability of the primers, mock clinical specimens containing human and RVFV RNAs were prepared. The entire RVFV genome was successfully amplified and sequenced at a viral concentration of 108 copies/mL. Given the universality, specificity, and clinical applicability of the primers, we anticipate that the RVFV universal primer pairs and the developed method will aid in RVFV phylogenomics and mutation detection.

Factors affecting RIG-I-Like receptors activation - New research direction for viral hemorrhagic fevers

Viral hemorrhagic fever (VHF) is a term referring to a group of life-threatening infections caused by several virus families (Arenaviridae, Bunyaviridae, Filoviridae and Flaviviridae). Depending on the virus, the infection can be mild and can be also characterized by an acute course with fever accompanied by hypervolemia and coagulopathy, resulting in bleeding and shock. It has been suggested that the course of the disease is strongly influenced by the activation of signaling pathways leading to RIG-I-like receptor-dependent interferon production. RIG-I-like receptors (RLRs) are one of two major receptor families that detect viral nucleic acid. RLR receptor activation is influenced by a number of factors that may have a key role in the differences that occur during the antiviral immune response in VHF. In the present study, we collected data on RLR receptors in viral hemorrhagic fevers and described factors that may influence the activation of the antiviral response. RLR receptors seem to be a good target for VHF research, which may contribute to better therapeutic and diagnostic strategies. However, due to the difficulty of conducting such studies in humans, we suggest using Lagovirus europaeus as an animal model for VHF.

MMV-db: vaccinomics and RNA-based therapeutics database for infectious hemorrhagic fever-causing mammarenaviruses

The recent viral outbreaks and the current pandemic situation urges us to timely address any emerging viral infections by designing therapeutic strategies. Multi-omics and therapeutic data are of great interest to develop early remedial interventions. This work provides a therapeutic data platform (Mammarenavirus (MMV)-db) for pathogenic mammarenaviruses with potential catastrophic effects on human health around the world. The database integrates vaccinomics and RNA-based therapeutics data for seven human pathogenic MMVs associated with severe viral hemorrhagic fever and lethality in humans. Protein-specific cytotoxic T lymphocytes, B lymphocytes, helper T-cell and interferon-inducing epitopes were mapped using a cluster of immune-omics-based algorithms and tools for the seven human pathogenic viral species. Furthermore, the physiochemical and antigenic properties were also explored to guide protein-specific multi-epitope subunit vaccine for each species. Moreover, highly efficacious RNAs (small Interfering RNA (siRNA), microRNA and single guide RNA (sgRNA)) after extensive genome-based analysis with therapeutic relevance were explored. All the therapeutic RNAs were further classified and listed on the basis of predicted higher efficacy. The online platform (http://www.mmvdb.dqweilab-sjtu.com/index.php) contains easily accessible data sets and vaccine designs with potential utility in further computational and experimental work. Conclusively, the current study provides a baseline data platform to secure better future therapeutic interventions against the hemorrhagic fever causing mammarenaviruses. Database URL: http://www.mmvdb.dqweilab-sjtu.com/index.php.

Third-generation smallpox vaccine strain-based recombinant vaccines for viral hemorrhagic fevers

Vaccinia virus has been used as a smallpox vaccine. Now that smallpox has been eradicated, the vaccinia virus is expected to be used as a bioterrorism countermeasure and a recombinant vaccine vector for other infectious diseases, such as viral hemorrhagic fevers. Many vaccinia virus strains were used as smallpox vaccines in the smallpox eradication campaign coordinated by the World Health Organization. These strains can be classified into generations, according to the history of improving production methods and efforts to reduce the adverse reactions. Significantly, the third-generation of smallpox vaccine strains, which include modified vaccinia Ankara (MVA) and LC16m8, are currently popular as recombinant vaccine vectors due to their well-balanced safety and immunogenicity profiles. The present review firstly focuses on the characteristics of the smallpox vaccine generations. The historical background of the development of the third-generation smallpox vaccine strains is detailed, along with the history of the transition of the vaccinia virus generation used as vectors for hemorrhagic fever vaccines to the third generation. Among the vaccinia viruses, MVA is currently the most commonly used vector for developing hemorrhagic fever vaccines, including dengue fever, yellow fever, Ebola viral disease, Lassa fever, Rift Valley fever, and Crimean-Congo hemorrhagic fever. LC16m8 is a vaccine candidate for severe fever with thrombocytopenia syndrome. The current status and recent advances in the development of these hemorrhagic fever vaccines using third-generation vaccinia strains are discussed.

Structural landscape of the complete genomes of dengue virus serotypes and other viral hemorrhagic fevers

BACKGROUND

With more than 300 million potentially infected people every year, and with the expanded habitat of mosquitoes due to climate change, Dengue virus (DENV) cannot be considered anymore only a tropical disease. The RNA secondary structure is a functional characteristic of RNA viruses, and together with the accumulated high-throughput sequencing data could provide general insights towards understanding virus biology. Here, we profiled the RNA secondary structure of > 7000 complete viral genomes from 11 different species focusing on viral hemorrhagic fevers, including DENV serotypes, EBOV, and YFV.

RESULTS

In our work we demonstrated that the secondary structure and presence of protein-binding domains in the genomes can be used as intrinsic signature to further classify the viruses. With our predictive approach, we achieved high prediction scores of the secondary structure (AUC up to 0.85 with experimental data), and computed consensus secondary structure profiles using hundreds of in silico models. We observed that viruses show different structural patterns, where e.g., DENV-2 and Ebola virus tend to be less structured than the other viruses. Furthermore, we observed virus-specific correlations between secondary structure and the number of interaction sites with human proteins, reaching a correlation of 0.89 in the case of Zika virus. We also identified that helicases-encoding regions are more structured in several flaviviruses, while the regions encoding for the contact proteins exhibit virus-specific clusters in terms of RNA structure and potential protein-RNA interactions. We also used structural data to study the geographical distribution of DENV, finding a significant difference between DENV-3 from Asia and South-America, where the structure is also driving the clustering more than sequence identity, which could imply different evolutionary routes of this subtype.

CONCLUSIONS

Our massive computational analysis provided novel results regarding the secondary structure and the interaction with human proteins, not only for DENV serotypes, but also for other flaviviruses and viral hemorrhagic fevers-associated viruses. We showed how the RNA secondary structure can be used to categorise viruses, and even to further classify them based on the interaction with proteins. We envision that these approaches can be used to further classify and characterise these complex viruses.

African Swine Fever Virus: A Review

African swine fever (ASF) is a highly contagious viral disease of swine which causes high mortality, approaching 100%, in domestic pigs. ASF is caused by a large, double stranded DNA virus, ASF virus (ASFV), which replicates predominantly in the cytoplasm of macrophages and is the only member of the Asfarviridae family, genus Asfivirus. The natural hosts of this virus include wild suids and arthropod vectors of the Ornithodoros genus. The infection of ASFV in its reservoir hosts is usually asymptomatic and develops a persistent infection. In contrast, infection of domestic pigs leads to a lethal hemorrhagic fever for which there is no effective vaccine. Identification of ASFV genes involved in virulence and the characterization of mechanisms used by the virus to evade the immune response of the host are recognized as critical steps in the development of a vaccine. Moreover, the interplay of the viral products with host pathways, which are relevant for virus replication, provides the basic information needed for the identification of potential targets for the development of intervention strategies against this disease.

Viral hemorrhagic fever in Pakistan: awareness among health care personnel

OBJECTIVE

To assess the level of knowledge regarding viral hemorrhagic fever (VHF) among healthcare personnel at two largest tertiary care hospitals in Karachi, Pakistan.

METHODS

A cross sectional convenience survey was conducted in February 2001 among doctors, nurses, laboratory technicians and janitors/orderlies of Jinnah Postgraduate Medical Centre and Civil Hospital, Karachi. The questionnaire included demographic information with their designation and knowledge level regarding VHF management, spread and prevention. Frequencies of the answers to each question were calculated for all questions and scores were assigned. The frequencies were also calculated on the basis of the designation of the respondent so that each group could be examined separately.

RESULTS

A total of 187 healthcare personnel (121 doctors, 31 nurses, 19 laboratory technicians and 16 janitors/orderlies) were interviewed. Forty three percent (81) respondents were males and 57% (106) were females. By designation 90% doctors, 71% nurses, 32% laboratory technicians and 6% janitors knew about VHF. Only 57% doctors (69) knew the common signs and symptoms of VHF. Isolation for affected patients was suggested by 65% nurses and 6% janitors. Knowledge regarding burial procedure of dead patients was low in all groups.

CONCLUSION

Differences in knowledge of different groups is obvious but it is essential to raise the knowledge regarding VHF at all levels including the housekeeping staff. There is also a need for continuing medical education (CME) for all health care personnel for the emerging health problems in Pakistan.

Cutaneous manifestations of biological warfare and related threat agents

The specter of biological warfare (BW) looms large in the minds of many Americans. The US government has required that emergency response teams in more than 100 American cities be trained by the year 2001 to recognize and contain a BW attack. The US military is requiring active duty soldiers to receive immunization against anthrax. Dermatologists need not feel helpless in the face of a potential BW attack. Many potential agents have cutaneous manifestations that the trained eye of a dermatologist can recognize. Through early recognition of a BW attack, dermatologists can aid public health authorities in diagnosing the cause so that preventive and containment measures can be instituted to mitigate morbidity and mortality. This article reviews bacterial, viral, and toxin threat agents and emphasizes those that would have cutaneous manifestations following an aerosol attack. We conclude with clues that can help one recognize a biological attack.

Clinical recognition and management of patients exposed to biological warfare agents

Concern regarding the use of biological agents--bacteria, viruses, or toxins--as tools of warfare or terrorism has led to measures to deter their use or, failing that, to deal with the consequences. Unlike chemical agents, which typically lead to violent disease syndromes within minutes at the site of exposure, diseases resulting from biological agents have incubation periods of days. Therefore, rather than a paramedic, it will likely be a physician who is first faced with evidence of the results of a biological attack. We provide here a primer on 10 classic biological warfare agents to increase the likelihood of their being considered in a differential diagnosis. Although the resultant diseases are rarely seen in many countries today, accepted diagnostic and epidemiologic principles apply; if the cause is identified quickly, appropriate therapy can be initiated and the impact of a terrorist attack greatly reduced.

Ebola haemorrhagic fever: experimental infection of monkeys

Experimental infection of rhesus and vervet monkeys with Ebola virus produced a uniformly fatal illness. The course of the disease resembled that found in man with weight loss, anorexia, fever, haemorrhages and skin rash being frequently seen. Viraemia was obvious within two days of infection and persisted until death which occurred between days five and eight. Virus was found in high concentrations in several organs but particularly in the liver, spleen, and lungs.

A rhesus monkey model for the study of Bolivian hemorrhagic fever

Two groups of rhesus monkeys were inoculated with either 10(5) (group 1) or 10(3) (group 2) plaque-forming units of Machupo virus, the etiologic virus of Bolivian hemorrhagic fever. The monkeys were observed for clinical signs; body temperatures, viremias, hematologic changes, and virus-neutralizing antibody were measured. The onset of clinical signs for groups 1 and 2 occurred on days 4-6 and 7-10, respectively, with fever, anorexia, and depression. These and other signs became more severe, and all of the monkeys died; the respective mean times to death for groups 1 and 2 were 14.3 and 19.5 days. Hematocrit, neutrophil, and lymphocyte values decreased in both groups until a few days before death and then increased slightly. Viremias in the two groups peaked on days 13 and 16, respectively, and persisted until death; the sole exception was one monkey in group 2 that developed neutralizing antibody by day 21. The response of the rhesus monkey to Machupo virus thus provides a useful model for the study of Bolivian hemorrhagic fever.