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The emergence of hitherto unknown viral pathogens presents a great challenge for researchers to develop effective therapeutics and vaccines within a short time to avoid an uncontrolled global spread, as seen during the coronavirus disease 2019 (COVID-19) pandemic. Therefore, rapid and simple methods to identify immunogenic antigens as potential therapeutical targets are urgently needed for a better pandemic preparedness. To address this problem, we chose the well-characterized Modified Vaccinia virus Ankara (MVA)-T7pol expression system to establish a workflow to identify immunogens when a new pathogen emerges, generate candidate vaccines, and test their immunogenicity in an animal model. By using this system, we detected severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2) nucleoprotein (N)-, and spike (S)-specific antibodies in COVID-19 patient sera, which is in line with the current literature and our observations from previous immunogenicity studies. Furthermore, we detected antibodies directed against the SARS-CoV-2-membrane (M) and -ORF3a proteins in COVID-19 patient sera and aimed to generate recombinant MVA candidate vaccines expressing either the M or ORF3a protein. When testing our candidate vaccines in a prime-boost immunization regimen in humanized HLA-A2.1-/HLA-DR1-transgenic H-2 class I-/class II-knockout mice, we were able to demonstrate M- and ORF3a-specific cellular and humoral immune responses. Hence, the established workflow using the MVA-T7pol expression system represents a rapid and efficient tool to identify potential immunogenic antigens and provides a basis for future development of candidate vaccines. [ABSTRACT FROM AUTHOR]

The rapid spread of SARS-CoV-2 clearly demonstrated the potential of zoonotic diseases to cause severe harm to public health. Having limited access to medical care combined with severe underreporting and a lack of active surveillance, Africa carries a high burden of neglected zoonotic diseases. Therefore, the epidemiological monitoring of pathogen circulation is essential. Recently, we found extensive Middle East respiratory syndrome coronavirus (MERS-CoV) prevalence in free-roaming dromedary camels from southern Tunisia. In this study, we aimed to investigate the seroprevalence, and thus the risk posed to public health, of two additional viral and two bacterial pathogens in Tunisian dromedaries: Rift Valley fever virus (RVFV), foot-and-mouth disease virus (FMDV), Coxiella burnetii and Brucella spp. via ELISA. With 73.6% seropositivity, most animals had previously been exposed to the causative agent of Q fever, C. burnetii. Additionally, 7.4% and 1.0% of the dromedaries had antibodies against Brucella and RVFV, respectively, while no evidence was found for the occurrence of FMDV. Our studies revealed considerable immunological evidence of various pathogens within Tunisian dromedary camels. Since these animals have intense contact with humans, they pose a high risk of transmitting serious zoonotic diseases during active infection. The identification of appropriate countermeasures is therefore highly desirable. [ABSTRACT FROM AUTHOR]

Simple Summary: South American camelids (SACs) constitute the greatest livestock wealth of the Andean populations. Approximately half a million people from the high Andean areas are dedicated to the breeding of SACs as their main activity. In general, infectious diseases, particularly diarrheal infections, cause high morbidity and mortality in offspring and adult animals. In the study, we demonstrated that multiple virus pathogens circulate among neonatal SACs, and coinfections from other viruses might be common among SAC crias. We also demonstrated, for the first-time anywhere, the circulation of mammalian orthoreovirus in SACs or camelids. Diarrheal infections can potentially impact livestock productivity, which translates into serious economic losses for the Peruvian SAC industry, especially within rural communities, directly impacting their livelihood. Better knowledge of the infections that afflict these animals will enable the implementation of measures for the prevention and control of pathogens, the results of which will ultimately be reflected in improving the quality of life of these communities. Enteric infections are a major cause of neonatal death in South American camelids (SACs). The aim of this study was to determine the prevalence of enteric viral pathogens among alpacas and llamas in Canchis, Cuzco, located in the southern Peruvian highland. Fecal samples were obtained from 80 neonatal alpacas and llamas and tested for coronavirus (CoV), mammalian orthoreovirus (MRV), and rotavirus A (RVA) by RT-PCR. Of the 80 fecal samples analyzed, 76 (95%) were positive for at least one of the viruses tested. Overall, the frequencies of positive samples were 94.1% and 100% among alpacas and llamas, respectively. Of the positive samples, 33 (43.4%) were monoinfected, while 43 (56.6%) had coinfections with two (83.7%) or three (16.3%) viruses. CoV was the most commonly detected virus (87.5%) followed by MRV (50%). RVA was detected only in coinfections. To our knowledge, this is the first description of MRV circulation in SACs or camelids anywhere. These data show that multiple viruses circulate widely among young alpaca and llama crias within the studied areas. These infections can potentially reduce livestock productivity, which translates into serious economic losses for rural communities, directly impacting their livelihoods. [ABSTRACT FROM AUTHOR]

Feline coronaviruses (FCoVs) infect both wild and domestic cat populations world-wide. FCoVs present as two main biotypes: the mild feline enteric coronavirus (FECV) and the fatal feline infectious peritonitis virus (FIPV). FIPV develops through mutations from FECV during a persistence infection. So far, the molecular mechanism of FECV-persistence and contributing factors for FIPV development may not be studied, since field FECV isolates do not grow in available cell culture models. In this work, we aimed at establishing feline ileum and colon organoids that allow the propagation of field FECVs. We have determined the best methods to isolate, culture and passage feline ileum and colon organoids. Importantly, we have demonstrated using GFP-expressing recombinant field FECV that colon organoids are able to support infection of FECV, which were unable to infect traditional feline cell culture models. These organoids in combination with recombinant FECVs can now open the door to unravel the molecular mechanisms by which FECV can persist in the gut for a longer period of time and how transition to FIPV is achieved. [ABSTRACT FROM AUTHOR]

Widespread vaccination programmes led to the global eradication of smallpox, which was certified by the World Health Organisation (WHO), and, since 1978, there has been no case of smallpox anywhere in the world. However, the viable variola virus (VARV), the causative agent of smallpox, is still kept in two maximum security laboratories in Russia and the USA. Despite the eradication of the disease smallpox, clandestine stocks of VARV may exist. In a rapidly changing world, the impact of an intentional VARV release in the human population would nowadays result in a public health emergency of global concern: vaccination programmes were abolished, the percentage of immunosuppressed individuals in the human population is higher, and an increased intercontinental air travel allows for the rapid viral spread of diseases around the world. The WHO has authorised the temporary retention of VARV to enable essential research for public health benefit to take place. This work aims to develop diagnostic tests, antiviral drugs, and safer vaccines. Advances in synthetic biology have made it possible to produce infectious poxvirus particles from chemicals in vitro so that it is now possible to reconstruct VARV. The status of smallpox in the post-eradication era is reviewed. [ABSTRACT FROM AUTHOR]