Biology subjects

Hoornweg, T. E.

Publications and source records attributed to Hoornweg, T. E..

4 recordsLinked to original sources

bioRxiv2025

The gH/gL/gO Complex of Elephant Endotheliotropic Herpesvirus 1A Functions as a Receptor Binding Complex

Elephant endotheliotropic herpesvirus (EEHV) causes a fatal haemorrhagic disease in young elephants and represents a major threat to the survival of these endangered species. Despite its clinical importance, the mechanisms of EEHV entry and host cell recognition remain poorly understood. Here, we show that the EEHV1A homolog of the Betaherpesvirus glycoprotein O (gO) assembles with glycoproteins H and L (gH/gL) to form a heterotrimeric complex analogous to the human cytomegalovirus (HCMV) gH/gL/gO trimer. Using single-particle cryo-electron microscopy, we determined the structure of the EEHV1A gH/gL/gO complex at 3.2 [A] resolution, revealing a conserved overall architecture but distinct gO topology and disulfide arrangement. The EEHV1A trimer, but not gH/gL alone, bound primary elephant endothelial cells, monocytes, and lymphocytes, indicating that gH/gL/gO serves as the receptor-binding complex of EEHV1A. This binding was specifically blocked by sera from naturally infected elephants, confirming its antigenic relevance. Finally, negative-stain electron microscopy polyclonal epitope mapping of gH/gL/gO-Fab complexes identified a Fab population that bound gO near the apex of the gH/gL/gO trimer, suggesting that these antibodies may interfere with gH/gL/gO-receptor interactions. Together, these findings define the molecular architecture and receptor-binding properties of the EEHV1A gH/gL/gO complex and provide a structural framework for the development of vaccines and antibody-based interventions against EEHV-associated disease.

microbiology↗

bioRxiv2023

Low gH/gL (sub)species-specific antibody levels indicate elephants at risk of fatal elephant endotheliotropic herpesvirus hemorrhagic disease

Elephant endotheliotropic herpesviruses (EEHVs), of which seven species and multiple subspecies are currently distinguished, naturally infect either Asian (Elephas maximus) or African elephants (Loxodonta species). While all adult elephants are latently infected with at least one EEHV (sub)species, EEHV infections in young elephants may lead to acute, fatal hemorrhagic disease (EEHV-HD). The disease is primarily observed in calves with low to non-detectable EEHV-specific antibodies, suggesting it is the result of an uncontrolled primary infection. Yet, young elephants showing high antibody levels in serological assays based on EEHV(1A) gB, which detect antibodies against multiple EEHV (sub)species, are not necessarily protected against EEHV-HD. To better determine which animals are at risk of EEHV-HD, we developed gB and gH/gL ELISAs for all Asian elephant EEHV (sub)species and assessed their specificity using 396 sera from 164 Asian elephants kept in Europeans zoos. Antibody levels measured against gB of different EEHV (sub)species correlated strongly with one another, indicating gB-specific antibodies are highly cross-reactive. In contrast, antibody responses towards gH/gL of different EEHV (sub)species were far less correlated and could be used to distinguish between infections with different (sub)species. Subsequently, antibody responses in sera of 23 EEHV-HD fatalities were analyzed. Whereas high antibody levels against gB could be detected in sera of multiple EEHV-HD fatalities, all fatalities had low antibody levels against gH/gL of the EEHV (sub)species they succumbed to. Overall, our data indicate that (sub)species-specific gH/gL ELISAs may be used to identify animals at risk of developing EEHV-HD upon infection with a particular EEHV (sub)species.

microbiology↗

bioRxiv2020

Elephant endotheliotropic herpesvirus is omnipresent in elephants in European zoos and an Asian elephant range country

Elephant endotheliotropic herpesviruses (EEHVs) are a group of evolutionary divergent herpesviruses that may cause acute, often lethal, hemorrhagic disease (EEHV-HD) in young elephants. Although EEHV was first discovered over 20 years ago, its prevalence in different elephant populations is still largely unknown, partially due to the lack of readily available, sensitive serological assays. In order to improve diagnostic tools for the detection of EEHV infections and to obtain insight in its spread among elephants, we developed novel ELISAs focusing on EEHV1A gB and gH/gL as antigens. Performance of the ELISAs was assessed using sera taken from 41 European zoo elephants and 69 semi-captive elephants from Laos, one of the Asian elephant range countries. Sera from all (sub)adult animals tested ([≥]5 years of age) showed high reactivity with both gB and gH/gL, whereas reactivity towards the antigens was generally lower for sera of juvenile animals (1 > 5 years). Only one (juvenile) animal, which was sampled directly after succumbing to EEHV-HD, was found to be seronegative for EEHV. The two other EEHV-HD cases tested showed low antibody levels, suggesting that all three cases died upon a primary EEHV infection. Direct comparison with another EEHV-specific ELISA previously used in two large serosurveys, showed that EEHV prevalence was underestimated before, likely due to aberrant folding of the antigen used. In conclusion, our study suggests that essentially all (semi-)captive (sub)adult elephants in European zoos and in Laos carry EEHV, and that young elephants with low antibody levels are at risk of dying from EEHV-HD. ImportanceOver the last 30 years, nearly 20% of all Asian elephants born in Western zoos succumbed to acute hemorrhagic disease caused by elephant endotheliotropic herpesvirus (EEHV-HD). Yet, the prevalence of EEHV in captive and wild elephant populations is still largely unknown, mainly due to the lack of readily available, sensitive serological assays. For this study two highly sensitive EEHV-specific ELISAs were developed. Using these assays, it was shown that nearly all elephants tested were seropositive for EEHV, with highest antibody levels detected in (sub)adult elephants. In contrast, antibody levels in EEHV-HD cases were very low or non-detectable. Lack of antibodies may thus be a risk factor for developing severe disease. As the novel ELISAs are low-tech in nature, these assays may easily be disseminated to local laboratories in zoos and elephant range countries in order to determine EEHV serostatus of individual animals or complete herds and (wild) populations.

microbiology↗

bioRxiv2020

Chikungunya virus requires an intact microtubule network for efficient viral genome delivery

Chikungunya virus (CHIKV) is a re-emerging mosquito-borne virus, which has rapidly spread around the globe thereby causing millions of infections. CHIKV is an enveloped virus belonging to the Togaviridae family and enters its host cell primarily via clathrin-mediated endocytosis. Upon internalization, the endocytic vesicle containing the virus particle moves through the cell and delivers the virus to early endosomes where membrane fusion is observed. Thereafter, the nucleocapsid dissociates and the viral RNA is translated into proteins. In this study, we examined the importance of the microtubule network during the early steps of infection and dissected the intracellular trafficking behavior of CHIKV particles during cell entry. We observed two distinct CHIKV intracellular trafficking patterns prior to membrane hemifusion. Whereas half of the CHIKV virions remained static during cell entry and fused in the cell periphery, the other half showed fast-directed microtubule-dependent movement prior to delivery to Rab5-positive early endosomes and predominantly fused in the perinuclear region of the cell. Disruption of the microtubule network reduced the number of infected cells. At these conditions, membrane hemifusion activity was not affected yet fusion was restricted to the cell periphery. Furthermore, follow-up experiments revealed that disruption of the microtubule network impairs the delivery of the viral genome to the cell cytosol. We therefore hypothesize that microtubules may direct the particle to a cellular location that is beneficial for establishing infection or aids in nucleocapsid uncoating. Author SummaryChikungunya virus (CHIKV) is an alphavirus that is transmitted to humans by infected mosquitoes. Disease symptoms can include fever, rash, myalgia, and long-lasting debilitating joint pains. Unfortunately, there is currently no licensed vaccine or antiviral treatment available to combat CHIKV. Understanding the virus:host interactions during the replication cycle of the virus is crucial for the development of effective antiviral therapies. In this study we elucidated the trafficking behavior of CHIKV particles early in infection. During cell entry, CHIKV virions require an intact microtubule network for efficient delivery of the viral genome into the host cell thereby increasing the chance to productively infect a cell.

microbiology↗