Identification of Two Independent COL5A1 Variants in Dogs with Ehlers-Danlos Syndrome.

The Ehlers-Danlos syndromes (EDS) are a heterogeneous group of heritable disorders affecting connective tissues. The mutations causing the various forms of EDS in humans are well characterized, but the genetic mutations causing EDS-like clinical pathology in dogs are not known, thus hampering accurate clinical diagnosis. Clinical analysis of two independent cases of skin hyperextensibility and fragility, one with pronounced joint hypermobility was suggestive of EDS. Whole-genome sequencing revealed de novo mutations of COL5A1 in both cases, confirming the diagnosis of the classical form of EDS. The heterozygous COL5A1 p.Gly1013ValfsTer260 mutation characterized in case 1 introduced a premature termination codon and would be expected to result in α1(V) mRNA nonsense-mediated mRNA decay and collagen V haploinsufficiency. While mRNA was not available from this dog, ultrastructural analysis of the dermis demonstrated variability in collagen fibril diameter and the presence of collagen aggregates, termed 'collagen cauliflowers', consistent with COL5A1 mutations underlying classical EDS. In the second case, DNA sequencing demonstrated a p.Gly1571Arg missense variant in the COL5A1 gene. While samples were not available for further analysis, such a glycine substitution would be expected to destabilize the strict molecular structure of the collagen V triple helix and thus affect protein stability and/or integration of the mutant collagen into the collagen V/collagen I heterotypic dermal fibrils. This is the first report of genetic variants in the COL5A1 gene causing the clinical presentation of EDS in dogs. These data provided further evidence of the important role of collagen V in dermal collagen fibrillogenesis. Importantly, from the clinical perspective, we showed the utility of DNA sequencing, combined with the established clinical criteria, in the accurate diagnosis of EDS in dogs

Natural reservoir Rousettus aegyptiacus bat host model of orthonairovirus infection identifies potential zoonotic spillover mechanisms

Abstract The human-pathogenic Kasokero virus (KASV; genus Orthonairovirus) has been isolated from the sera of Egyptian rousette bats (ERBs; Rousettus aegyptiacus) captured in Uganda and unengorged Ornithodoros (Reticulinasus) faini ticks collected from the rock crevices of ERB colonies in South Africa and Uganda. Although evidence suggests that KASV is maintained in an enzootic transmission cycle between O. (R.) faini ticks and ERBs with potential for incidental virus spillover to humans through the bite of an infected tick, the vertebrate reservoir status of ERBs for KASV has never been experimentally evaluated. Furthermore, the potential for bat-to-bat and bat-to-human transmission of KASV is unknown. Herein, we inoculate two groups of ERBs with KASV; one group of bats is serially sampled to assess viremia, oral, fecal, and urinary shedding and the second group of bats is serially euthanized to assess virus-tissue tropism. Throughout the study, none of the bats exhibit overt signs of clinical disease. Following the detection of high KASV loads of long duration in blood, oral, fecal, and urine specimens collected from ERBs in the serial sampling group, all bats seroconvert to KASV. ERBs from the serial euthanasia group exhibit high KASV loads indicative of virus replication in the skin at the inoculation site, spleen, and inguinal lymph node tissue, and histopathology and in situ hybridization reveal virus replication in the liver and self-limiting, KASV-induced lymphohistiocytic hepatitis. The results of this study suggest that ERBs are competent, natural vertebrate reservoir hosts for KASV that can sustain viremias of appropriate magnitude and duration to support virus maintenance through bat-tick-bat transmission cycles. Viral shedding data suggests that KASV might also be transmitted bat-to-bat and highlights the potential for KASV spillover to humans through contact with infectious oral secretions, feces, or urine

Histopathologic and Immunohistochemical Evaluation of Induced Lesions, Tissue Tropism and Host Responses following Experimental Infection of Egyptian Rousette Bats (Rousettus aegyptiacus) with the Zoonotic Paramyxovirus, Sosuga Virus

Ecological and experimental infection studies have identified Egyptian rousette bats (ERBs; Rousettus aegyptiacus: family Pteropodidae) as a reservoir host for the zoonotic rubula-like paramyxovirus Sosuga virus (SOSV). A serial sacrifice study of colony-bred ERBs inoculated with wild-type, recombinant SOSV identified small intestines and salivary gland as major sites of viral replication. In the current study, archived formalin-fixed paraffin-embedded (FFPE) tissues from the serial sacrifice study were analyzed in depth—histologically and immunohistochemically, for SOSV, mononuclear phagocytes and T cells. Histopathologic lesion scores increased over time and viral antigen persisted in a subset of tissues, indicating ongoing host responses and underscoring the possibility of chronic infection. Despite the presence of SOSV NP antigen and villus ulcerations in the small intestines, there were only mild increases in mononuclear phagocytes and T cells, a host response aligned with disease tolerance. In contrast, there was a statistically significant, robust and targeted mononuclear phagocyte cell responses in the salivary glands at 21 DPI, where viral antigen was sparse. These findings may have broader implications for chiropteran–paramyxovirus interactions, as bats are hypothesized to be the ancestral hosts of this diverse virus family and for ERB immunology in general, as this species is also the reservoir host for the marburgviruses Marburg virus (MARV) and Ravn virus (RAVV) (family Filoviridae)

Experimental infection of Egyptian rousette bats (Rousettus aegyptiacus) with Sosuga virus demonstrates potential transmission routes for a bat-borne human pathogenic paramyxovirus.

In August 2012, a wildlife biologist became severely ill after becoming infected with a novel paramyxovirus, termed Sosuga virus. In the weeks prior to illness, the patient worked with multiple species of bats in South Sudan and Uganda, including Egyptian rousette bats (ERBs: Rousettus aegyptiacus). A follow-up study of Ugandan bats found multiple wild-caught ERBs to test positive for SOSV in liver and spleen. To determine the competency of these bats to act as a natural reservoir host for SOSV capable of infecting humans, captive-bred ERBs were inoculated with a recombinant SOSV, representative of the patient's virus sequence. The bats were inoculated subcutaneously, sampled daily (blood, urine, fecal, oral and rectal swabs) and serially euthanized at predetermined time points. All inoculated bats became infected with SOSV in multiple tissues and blood, urine, oral, rectal and fecal swabs tested positive for SOSV RNA. No evidence of overt morbidity or mortality were observed in infected ERBs, although histopathological examination showed subclinical disease in a subset of tissues. Importantly, SOSV was isolated from oral/rectal swabs, urine and feces, demonstrating shedding of infectious virus concomitant with systemic infection. All bats euthanized at 21 days post-inoculation (DPI) seroconverted to SOSV between 16 and 21 DPI. These results are consistent with ERBs being competent reservoir hosts for SOSV with spillover potential to humans

Coordinated inflammatory responses dictate Marburg virus control by reservoir bats

Abstract Bats are increasingly recognized as reservoirs of emerging zoonotic pathogens. Egyptian rousette bats (ERBs) are the known reservoir of Marburg virus (MARV), a filovirus that causes deadly Marburg virus disease (MVD) in humans. However, ERBs harbor MARV asymptomatically, likely due to a coadapted and specific host immunity-pathogen relationship. Recently, we measured transcriptional responses in MARV-infected ERB whole tissues, showing that these bats possess a disease tolerant strategy that limits pro-inflammatory gene induction, presumably averting MVD-linked immunopathology. However, the host resistant strategy by which ERBs actively limit MARV burden remains elusive, which we hypothesize requires localized inflammatory responses unresolvable at bulk-tissue scale. Here, we use dexamethasone to attenuate ERB pro-inflammatory responses and assess MARV replication, shedding and disease. We show that MARV-infected ERBs naturally mount coordinated pro-inflammatory responses at liver foci of infection, comprised of recruited mononuclear phagocytes and T cells, the latter of which proliferate with likely MARV-specificity. When pro-inflammatory responses are diminished, ERBs display heightened MARV replication, oral/rectal shedding and severe MVD-like liver pathology, demonstrating that ERBs balance immunoprotective tolerance with discreet MARV-resistant pro-inflammatory responses. These data further suggest that natural ERB immunomodulatory stressors like food scarcity and habitat disruption may potentiate viral shedding, transmission and therefore outbreak risk

SARS-CoV-2 RBD trimer protein adjuvanted with Alum-3M-052 protects from SARS-CoV-2 infection and immune pathology in the lung

Efficient vaccines for SARS-CoV-2 are needed. Here, the authors show that a trimeric form of the receptor-binding domain of SARS-CoV-2 spike adjuvanted with alum-3M-052 protects non-human primates from disease and inhibits infection