Deciphering MERS-CoV Evolution in Dromedary Camels

The evolutionary drivers and correlates of viral host jumps

Most emerging and re-emerging infectious diseases stem from viruses that naturally circulate in non-human vertebrates. When these viruses cross over into humans, they can cause disease outbreaks, epidemics and pandemics. While zoonotic host jumps have been extensively studied from an ecological perspective, little attention has gone into characterizing the evolutionary drivers and correlates underlying these events. To address this gap, we harnessed the entirety of publicly available viral genomic data, employing a comprehensive suite of network and phylogenetic analyses to investigate the evolutionary mechanisms underpinning recent viral host jumps. Surprisingly, we find that humans are as much a source as a sink for viral spillover events, insofar as we infer more viral host jumps from humans to other animals than from animals to humans. Moreover, we demonstrate heightened evolution in viral lineages that involve putative host jumps. We further observe that the extent of adaptation associated with a host jump is lower for viruses with broader host ranges. Finally, we show that the genomic targets of natural selection associated with host jumps vary across different viral families, with either structural or auxiliary genes being the prime targets of selection. Collectively, our results illuminate some of the evolutionary drivers underlying viral host jumps that may contribute to mitigating viral threats across species boundaries.

Avian Orthoavulavirus Type-1 as Vaccine Vector against Respiratory Viral Pathogens in Animal and Human

Avian orthoavulaviruses type-1 (AOaV-1) have recently transitioned from animal vaccine vector to a bona fide vaccine delivery vehicle in human. Owing to induction of robust innate and adaptive immune responses in mucus membranes in both birds and mammals, AOaVs offer an attractive vaccine against respiratory pathogens. The unique features of AOaVs include over 50 years of safety profile, stable expression of foreign genes, high infectivity rates in avian and mammalian hosts, broad host spectrum, limited possibility of recombination and lack of pre-existing immunity in humans. Additionally, AOaVs vectors allow the production of economical and high quantities of vaccine antigen in chicken embryonated eggs and several GMP-grade mammalian cell lines. In this review, we describe the biology of AOaVs and define protocols to manipulate AOaVs genomes in effectively designing vaccine vectors. We highlighted the potential and established portfolio of AOaV-based vaccines for multiple respiratory and non-respiratory viruses of veterinary and medical importance. We comment on the limitations of AOaV-based vaccines and propose mitigations strategies. The exploitation of AOaVs vectors is expanding at an exciting pace; thus, we have limited the scope to their use as vaccines against viral pathogens in both animals and humans.

Zoonotic implications of camel diseases in Iran

Approximately 60% of all human pathogens and 75% of emerging infectious diseases are zoonotic (of animal origin). Camel zoonotic diseases can be encountered in all camel-rearing countries. In this article, all studies carried out on camel zoonotic diseases in Iran are reviewed to show the importance of camels for public health in this country. More than 900 published documents were systematically searched to find relevant studies from 1,890 until late 2018. The collected articles were classified according to the aetiological agents. In this study, 19 important zoonotic diseases were reported among Iranian camels including listeriosis, leptospirosis, plague, Q fever, brucellosis, campylobacteriosis, tuberculosis, pasteurellosis, clostridiosis, salmonellosis, Escherichia coli infections, rabies, camelpox, Middle East respiratory syndrome coronavirus, Crimean-Congo haemorrhagic fever, echinococcosis, cryptosporidiosis, toxoplasmosis and dermatophytosis, most of which belong to bacterial, viral, parasitic and fungal pathogens, respectively. Results show that camels are one of the most important sources of infections and diseases in human; therefore, continuous monitoring and inspection programs are necessary to prevent the outbreak of zoonotic diseases caused by this animal in humans.

Exploring the Prospects of Engineered Newcastle Disease Virus in Modern Vaccinology

Many traditional vaccines have proven to be incapable of controlling newly emerging infectious diseases. They have also achieved limited success in the fight against a variety of human cancers. Thus, innovative vaccine strategies are highly needed to overcome the global burden of these diseases. Advances in molecular biology and reverse genetics have completely restructured the concept of vaccinology, leading to the emergence of state-of-the-art technologies for vaccine design, development and delivery. Among these modern vaccine technologies are the recombinant viral vectored vaccines, which are known for their incredible specificity in antigen delivery as well as the induction of robust immune responses in the vaccinated hosts. Although a number of viruses have been used as vaccine vectors, genetically engineered Newcastle disease virus (NDV) possesses some useful attributes that make it a preferable candidate for vectoring vaccine antigens. Here, we review the molecular biology of NDV and discuss the reverse genetics approaches used to engineer the virus into an efficient vaccine vector. We then discuss the prospects of the engineered virus as an efficient vehicle of vaccines against cancer and several infectious diseases of man and animals.

A Review of Zoonotic Pathogens of Dromedary Camels

Dromedary, or one-humped, camels Camelus dromedarius are an almost exclusively domesticated species that are common in arid areas as both beasts of burden and production animals for meat and milk. Currently, there are approximately 30 million dromedary camels, with highest numbers in Africa and the Middle East. The hardiness of camels in arid regions has made humans more dependent on them, especially as a stable protein source. Camels also carry and may transmit disease-causing agents to humans and other animals. The ability for camels to act as a point source or vector for disease is a concern due to increasing human demands for meat, lack of biosafety and biosecurity protocols in many regions, and a growth in the interface with wildlife as camel herds become sympatric with non-domestic species. We conducted a literature review of camel-borne zoonotic diseases and found that the majority of publications (65%) focused on Middle East respiratory syndrome (MERS), brucellosis, Echinococcus granulosus, and Rift Valley fever. The high fatality from MERS outbreaks during 2012-2016 elicited an immediate response from the research community as demonstrated by a surge of MERS-related publications. However, we contend that other camel-borne diseases such as Yersinia pestis, Coxiella burnetii, and Crimean-Congo hemorrhagic fever are just as important to include in surveillance efforts. Camel populations, particularly in sub-Saharan Africa, are increasing exponentially in response to prolonged droughts, and thus, the risk of zoonoses increases as well. In this review, we provide an overview of the major zoonotic diseases present in dromedary camels, their risk to humans, and recommendations to minimize spillover events.

Temporal dynamics of Middle East respiratory syndrome coronavirus in the Arabian Peninsula, 2012-2017

Middle East respiratory syndrome coronavirus (MERS-CoV) remains a notable disease and poses a significant threat to global public health. The Arabian Peninsula is considered a major global epicentre for the disease and the virus has crossed regional and continental boundaries since 2012. In this study, we focused on exploring the temporal dynamics of MERS-CoV in human populations in the Arabian Peninsula between 2012 and 2017, using publicly available data on case counts and combining two analytical methods. Disease progression was assessed by quantifying the time-dependent reproductive number (TD-Rs), while case series temporal pattern was modelled using the AutoRegressive Integrated Moving Average (ARIMA). We accounted for geographical variability between three major affected regions in Saudi Arabia including Eastern Province, Riyadh and Makkah. In Saudi Arabia, the epidemic size was large with TD-Rs >1, indicating significant spread until 2017. In both Makkah and Riyadh regions, the epidemic progression reached its peak in April 2014 (TD-Rs > 7), during the highest incidence period of MERS-CoV cases. In Eastern Province, one unique super-spreading event (TD-R > 10) was identified in May 2013, which comprised of the most notable cases of human-to-human transmission. Best-fitting ARIMA model inferred statistically significant biannual seasonality in Riyadh region, a region characterised by heavy seasonal camel-related activities. However, no statistical evidence of seasonality was identified in Eastern Province and Makkah. Instead, both areas were marked by an endemic pattern of cases with sporadic outbreaks. Our study suggested new insights into the epidemiology of the virus, including inferences about epidemic progression and evidence for seasonality. Despite the inherent limitations of the available data, our conclusions provide further guidance to currently implement risk-based surveillance in high-risk populations and, subsequently, improve related interventions strategies against the epidemic at country and regional levels.

The Middle East Respiratory Syndrome Coronavirus - A Continuing Risk to Global Health Security

Two new zoonotic coronaviruses causing disease in humans (Zumla et al. 2015a; Hui and Zumla 2015; Peiris et al. 2003; Yu et al. 2014) have been the focus of international attention for the past 14 years due to their epidemic potential; (1) The Severe Acute Respiratory Syndrome coronavirus (SARS-CoV) (Peiris et al. 2003) first discovered in China in 2001 caused a major global epidemic of the Severe Acute Respiratory Syndrome (SARS). (2) The Middle East respiratory syndrome coronavirus (MERS-CoV) is a new corona virus isolated for the first time in a patients who died of severe lower respiratory tract infection in Jeddah (Saudi Arabia) in June 2012 (Zaki et al. 2012). The disease has been named Middle East Respiratory Syndrome (MERS) and it has remained on the radar of global public health authorities because of recurrent nosocomial and community outbreaks, and its association with severe disease and high mortality rates (Assiri et al. 2013a; Al-Abdallat et al. 2014; Memish et al. 2013a; Oboho et al. 2015; The WHO MERS-CoV Research Group 2013; Cotten et al. 2013a; Assiri et al. 2013b; Memish et al. 2013b; Azhar et al. 2014; Kim et al. 2015; Wang et al. 2015; Hui et al. 2015a). Cases of MERS have been reported from all continents and have been linked with travel to the Middle East (Hui et al. 2015a; WHO 2015c). The World Health Organization (WHO) have held nine meetings of the Emergency Committee (EC) convened by the Director-General under the International Health Regulations (IHR 2005) regarding MERS-CoV (WHO 2015c). There is wishful anticipation in the political and scientific communities that MERS-CoV like SARS-CoV will disappear with time. However it’s been nearly 4 years since the first discovery of MERS-CoV, and MERS cases continue to be reported throughout the year from the Middle East (WHO 2015c). There is a large MERS-CoV camel reservoir, and there is no specific treatment or vaccine (Zumla et al. 2015a). With 10 million people visiting Saudi Arabia every year for Umrah and/or Hajj, the potential risk of global spread is ever present (Memish et al. 2014a; McCloskey et al. 2014; Al-Tawfiq et al. 2014a).

Epidemiological investigation of Middle East respiratory syndrome coronavirus in dromedary camel farms linked with human infection in Abu Dhabi Emirate, United Arab Emirates

The objective of this research was to investigate the prevalence of Middle East respiratory syndrome coronavirus (MERS-CoV) infection primarily in dromedary camel farms and the relationship of those infections with infections in humans in the Emirate of Abu Dhabi. Nasal swabs from 1113 dromedary camels (39 farms) and 34 sheep (1 farm) and sputum samples from 2 MERS-CoV-infected camel farm owners and 1 MERS-CoV-infected sheep farm owner were collected. Samples from camels and humans underwent real-time reverse-transcription quantitative PCR screening to detect MERS-CoV. In addition, sequencing and phylogenetic analysis of partially characterized MERS-CoV genome fragments obtained from camels were performed. Among the 40 farms, 6 camel farms were positive for MERS-CoV; the virus was not detected in the single sheep farm. The maximum duration of viral shedding from infected camels was 2 weeks after the first positive test result as detected in nasal swabs and in rectal swabs obtained from infected calves. Three partial camel sequences characterized in this study (open reading frames 1a and 1ab, Spike1, Spike2, and ORF4b) together with the corresponding regions of previously reported MERS-CoV sequence obtained from one farm owner were clustering together within the larger MERS-CoV sequences cluster containing human and camel isolates reported for the Arabian Peninsula. Data provided further evidence of the zoonotic potential of MERS-CoV infection and strongly suggested that camels may have a role in the transmission of the virus to humans.

Taking forward a 'One Health' approach for turning the tide against the Middle East respiratory syndrome coronavirus and other zoonotic pathogens with epidemic potential

The appearance of novel pathogens of humans with epidemic potential and high mortality rates have threatened global health security for centuries. Over the past few decades new zoonotic infectious diseases of humans caused by pathogens arising from animal reservoirs have included West Nile virus, Yellow fever virus, Ebola virus, Nipah virus, Lassa Fever virus, Hanta virus, Dengue fever virus, Rift Valley fever virus, Crimean-Congo haemorrhagic fever virus, severe acute respiratory syndrome coronavirus, highly pathogenic avian influenza viruses, Middle East Respiratory Syndrome Coronavirus, and Zika virus. The recent Ebola Virus Disease epidemic in West Africa and the ongoing Zika Virus outbreak in South America highlight the urgent need for local, regional and international public health systems to be be more coordinated and better prepared. The One Health concept focuses on the relationship and interconnectedness between Humans, Animals and the Environment, and recognizes that the health and wellbeing of humans is intimately connected to the health of animals and their environment (and vice versa). Critical to the establishment of a One Health platform is the creation of a multidisciplinary team with a range of expertise including public health officers, physicians, veterinarians, animal husbandry specialists, agriculturalists, ecologists, vector biologists, viral phylogeneticists, and researchers to co-operate, collaborate to learn more about zoonotic spread between animals, humans and the environment and to monitor, respond to and prevent major outbreaks. We discuss the unique opportunities for Middle Eastern and African stakeholders to take leadership in building equitable and effective partnerships with all stakeholders involved in human and health systems to take forward a 'One Health' approach to control such zoonotic pathogens with epidemic potential.