Isolation and Characterization of Akhmeta Virus from Wild-Caught Rodents (Apodemus spp.) in Georgia

Clinical Manifestations of an Outbreak of Monkeypox Virus in Captive Chimpanzees in Cameroon, 2016

Monkeypox virus (MPXV) is a reemerging virus of global concern. An outbreak of clade I MPXV affected 20 captive chimpanzees in Cameroon in 2016. We describe the epidemiology, virology, phylogenetics, and clinical progression of this outbreak. Clinical signs included exanthema, facial swelling, perilaryngeal swelling, and eschar. Mpox can be lethal in captive chimpanzees, with death likely resulting from respiratory complications. We advise avoiding anesthesia in animals with respiratory signs to reduce the likelihood of death. This outbreak presented a risk to animal care staff. There is a need for increased awareness and a One Health approach to preparation for outbreaks in wildlife rescue centers in primate range states where MPXV occurs. Control measures should include quarantining affected animals, limiting human contacts, surveillance of humans and animals, use of personal protective equipment, and regular decontamination of enclosures.

Human mpox: global trends, molecular epidemiology and options for vaccination

The eradication of smallpox and the cessation of vaccination have led to the growth of the susceptible human population to poxviruses. This has led to the increasing detection of zoonotic orthopoxviruses. Among those viruses, monkeypox virus (MPV) is the most commonly detected in Western and Central African regions. Since 2022, MPV is causing local transmission in newly affected countries all over the world. While the virus causing the current outbreak remains part of clade II (historically referred to as West African clade), it has a significant number of mutations as compared to other clade II sequences and is therefore referred to as clade IIb. It remains unclear whether those mutations may have caused a change in the virus phenotype. Vaccine effectiveness data show evidence of a high cross-protection of vaccines designed to prevent smallpox against mpox. These vaccines therefore represent a great opportunity to control human-to-human transmission, provided that their availability has short time-frames and that mistakes from the recent past (vaccine inequity) will not be reiterated.

An Update of Orthopoxvirus Molecular Evolution

Although variola virus (VARV) has been eradicated through widespread vaccination, other orthopoxviruses pathogenic for humans circulate in nature. Recently, new orthopoxviruses, including some able to infect humans, have been found and their complete genomes have been sequenced. Questions about the orthopoxvirus mutation rate and the emergence of new threats to humankind as a result of the evolution of circulating orthopoxviruses remain open. Based on contemporary data on ancient VARV DNA and DNA of new orthopoxvirus species, an analysis of the molecular evolution of orthopoxviruses was carried out and the timescale of their emergence was estimated. It was calculated that the orthopoxviruses of the Old and New Worlds separated approximately 40,000 years ago; the recently discovered Akhmeta virus and Alaskapox virus separated from other orthopoxviruses approximately 10,000–20,000 years ago; the rest of modern orthopoxvirus species originated from 1700 to 6000 years ago, with the exception of VARV, which emerged in approximately 300 AD. Later, there was a separation of genetic variants of some orthopoxvirus species, so the monkeypox virus West African subtype originated approximately 600 years ago, and the VARV minor alastrim subtype emerged approximately 300 years ago.

New methylene blue derivatives suggest novel anti-orthopoxviral strategies

Decades after the eradication of smallpox and the discontinuation of routine smallpox vaccination, over half of the world's population is immunologically naïve to variola virus and other orthopoxviruses (OPXVs). Even in those previously vaccinated against smallpox, protective immunity wanes over time. As such, there is a concomitant increase in the incidence of human OPXV infections worldwide. To identify novel antiviral compounds with potent anti-OPXV potential, we characterized the inhibitory activity of PAV-866 and other methylene blue derivatives against the prototypic poxvirus, vaccinia virus (VACV). These compounds inactivated virions prior to infection and consequently inhibited viral binding, fusion and entry. The compounds exhibited strong virucidal activity at non-cytotoxic concentrations, and inhibited VACV infection when added before, during or after viral adsorption. The compounds were effective against other OPXVs including monkeypox virus, cowpox virus and the newly identified Akhmeta virus. Altogether, these findings reveal a novel mode of inhibition that has not previously been demonstrated for small molecule compounds against VACV. Additional studies are in progress to determine the in vivo efficacy of these compounds against OPXVs and further characterize the anti-viral effects of these derivatives.

Exploring the potential roles of some rodents in the transmission of the Middle East respiratory syndrome coronavirus

Middle East respiratory syndrome coronavirus (MERS-CoV) is one of the recently identified zoonotic coronaviruses. The one-hump camels are believed to play important roles in the evolution and transmission of the virus. The animal-to-animal, as well as the animal-to-human transmission in the context of MERS-CoV infection, were reported. The camels shed the virus in some of their secretions, especially the nasal tract. However, there are many aspects of the transmission cycle of the virus from animals to humans that are still not fully understood. Rodents played important roles in the transmission of many pathogens, including viruses and bacteria. They have been implicated in the evolution of many human coronaviruses, especially HCoV-OC43 and HCoV-HKU1. However, the role of rodents in the transmission of MERS-CoV still requires more exploration. To achieve this goal, we identified MERS-CoV that naturally infected dromedary camel by molecular surveillance. We captured 15 of the common rodents (rats, mice, and jerboa) sharing the habitat with these animals. We collected both oral and rectal swabs from these animals and then tested them by the commercial MERS-CoV real-time-PCR kits using two targets. Despite the detection of the viral shedding in the nasal swabs of some of the dromedary camels, none of the rodents tested positive for the virus during the tenure of this study. We concluded that these species of rodents did not harbor the virus and are most unlikely to contribute to the transmission of the MERS-CoV. However, further large-scale studies are required to confirm the potential roles of rodents in the context of the MERS-CoV transmission cycle, if any.

Here, There, and Everywhere: The Wide Host Range and Geographic Distribution of Zoonotic Orthopoxviruses

The global emergence of zoonotic viruses, including poxviruses, poses one of the greatest threats to human and animal health. Forty years after the eradication of smallpox, emerging zoonotic orthopoxviruses, such as monkeypox, cowpox, and vaccinia viruses continue to infect humans as well as wild and domestic animals. Currently, the geographical distribution of poxviruses in a broad range of hosts worldwide raises concerns regarding the possibility of outbreaks or viral dissemination to new geographical regions. Here, we review the global host ranges and current epidemiological understanding of zoonotic orthopoxviruses while focusing on orthopoxviruses with epidemic potential, including monkeypox, cowpox, and vaccinia viruses.

Laboratory Infection of Novel Akhmeta Virus in CAST/EiJ Mice

Akhmeta virus is a zoonotic Orthopoxvirus first identified in 2013 in the country of Georgia. Subsequent ecological investigations in Georgia have found evidence that this virus is widespread in its geographic distribution within the country and in its host-range, with rodents likely involved in its circulation in the wild. Yet, little is known about the pathogenicity of this virus in rodents. We conducted the first laboratory infection of Akhmeta virus in CAST/EiJ Mus musculus to further characterize this novel virus. We found a dose-dependent effect on mortality and weight loss (p < 0.05). Anti-orthopoxvirus antibodies were detected in the second- and third-highest dose groups (5 × 10⁴ pfu and 3 × 10² pfu) at euthanasia by day 10, and day 14 post-infection, respectively. Anti-orthopoxvirus antibodies were not detected in the highest dose group (3 × 10⁶ pfu), which were euthanized at day 7 post-infection and had high viral load in tissues, suggesting they succumbed to disease prior to mounting an effective immune response. In order of highest burden, viable virus was detected in the nostril, lung, tail, liver and spleen. All individuals tested in the highest dose groups were DNAemic. Akhmeta virus was highly pathogenic in CAST/EiJ Mus musculus, causing 100% mortality when ≥3 × 10² pfu was administered.

Relatives of rubella virus in diverse mammals

Since 1814, when rubella was first described, the origins of the disease and its causative agent, rubella virus (Matonaviridae: Rubivirus), have remained unclear1. Here we describe ruhugu virus and rustrela virus in Africa and Europe, respectively, which are, to our knowledge, the first known relatives of rubella virus. Ruhugu virus, which is the closest relative of rubella virus, was found in apparently healthy cyclops leaf-nosed bats (Hipposideros cyclops) in Uganda. Rustrela virus, which is an outgroup to the clade that comprises rubella and ruhugu viruses, was found in acutely encephalitic placental and marsupial animals at a zoo in Germany and in wild yellow-necked field mice (Apodemus flavicollis) at and near the zoo. Ruhugu and rustrela viruses share an identical genomic architecture with rubella virus2,3. The amino acid sequences of four putative B cell epitopes in the fusion (E1) protein of the rubella, ruhugu and rustrela viruses and two putative T cell epitopes in the capsid protein of the rubella and ruhugu viruses are moderately to highly conserved4-6. Modelling of E1 homotrimers in the post-fusion state predicts that ruhugu and rubella viruses have a similar capacity for fusion with the host-cell membrane5. Together, these findings show that some members of the family Matonaviridae can cross substantial barriers between host species and that rubella virus probably has a zoonotic origin. Our findings raise concerns about future zoonotic transmission of rubella-like viruses, but will facilitate comparative studies and animal models of rubella and congenital rubella syndrome.