Vaccine development for zoonotic viral diseases caused by positive‑sense single‑stranded RNA viruses belonging to the Coronaviridae and Togaviridae families (Review)

Outbreaks of zoonotic viral diseases pose a severe threat to public health and economies worldwide, with this currently being more prominent than it previously was human history. These emergency zoonotic diseases that originated and transmitted from vertebrates to humans have been estimated to account for approximately one billion cases of illness and have caused millions of deaths worldwide annually. The recent emergence of severe acute respiratory syndrome coronavirus-2 (coronavirus disease 2019) is an excellent example of the unpredictable public health threat causing a pandemic. The present review summarizes the literature data regarding the main vaccine developments in human clinical phase I, II and III trials against the zoonotic positive-sense single-stranded RNA viruses belonging to the Coronavirus and Alphavirus genera, including severe acute respiratory syndrome, Middle east respiratory syndrome, Venezuelan equine encephalitis virus, Semliki Forest virus, Ross River virus, Chikungunya virus and O'nyong-nyong virus. That there are neither vaccines nor effective antiviral drugs available against most of these viruses is undeniable. Therefore, new explosive outbreaks of these zoonotic viruses may surely be expected. The present comprehensive review provides an update on the status of vaccine development in different clinical trials against these viruses, as well as an overview of the present results of these trials.

Persistent Joint Pain Following Arthropod Virus Infections

PURPOSE OF REVIEW

Persistent joint pain is a common manifestation of arthropod-borne viral infections and can cause long-term disability. We review the epidemiology, pathophysiology, diagnosis, and management of arthritogenic alphavirus infection.

RECENT FINDINGS

The global re-emergence of alphaviral outbreaks has led to an increase in virus-induced arthralgia and arthritis. Alphaviruses, including Chikungunya, O'nyong'nyong, Sindbis, Barmah Forest, Ross River, and Mayaro viruses, are associated with acute and/or chronic rheumatic symptoms. Identification of Mxra8 as a viral entry receptor in the alphaviral replication pathway creates opportunities for treatment and prevention. Recent evidence suggesting virus does not persist in synovial fluid during chronic chikungunya infection indicates that immunomodulators may be given safely. The etiology of persistent joint pain after alphavirus infection is still poorly understood. New diagnostic tools along and evidence-based treatment could significantly improve morbidity and long-term disability.

Ross River Virus Antibody Prevalence, Fiji Islands, 2013-2015

A unique outbreak of Ross River virus (RRV) infection was reported in Fiji in 1979. In 2013, RRV seroprevalence among residents was 46.5% (362/778). Of the residents who were seronegative in 2013 and retested in 2015, 10.9% (21/192) had seroconverted to RRV, suggesting ongoing endemic circulation of RRV in Fiji.

Low chikungunya virus seroprevalence two years after emergence in Fiji

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Chikungunya virus (CHIKV) infections were recorded in Fiji between 2015 and 2017.

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We performed serological testing on serum from 320 Fijians sampled in 2017.

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CHIKV seroprevalence increased from 0.9% in 2015 to 12.8% in 2017.

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Of the 198 participants seronegative in 2015, 31 (15.7%) were seropositive in 2017.

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Low CHIKV transmission occurred during the two years following emergence in Fiji.

Objectives

In Fiji, autochthonous chikungunya virus (CHIKV) infection was first detected in March 2015. In a previous serosurvey conducted during October–November 2015, we reported a prevalence of anti-CHIKV IgG antibodies of 0.9%. In the present study, we investigated the seroprevalence of CHIKV two years after its emergence in Fiji.

Methods

Sera from 320 residents of Fiji recruited in June 2017, from the same cohort of individuals that participated in the serosurvey in 2015, were tested for the presence of IgG antibodies against CHIKV using a recombinant antigen-based microsphere immunoassay.

Results

Between 2015 and 2017, CHIKV seroprevalence among residents increased from 0.9% (3/333) to 12.8% (41/320). Of the participants with available serum samples collected in both 2015 and 2017 (n = 200), 31 (15.5%) who were seronegative in 2015 had seroconverted to CHIKV in 2017.

Conclusions

Our findings suggest that low-level transmission of CHIKV occurred during the two years following the emergence of the virus in Fiji. No CHIKV infection has been reported in Fiji since 2017, but due to the presumed low herd immunity of the population, the risk of CHIKV re-emergence is high. Consequently, chikungunya should be considered in the differential diagnosis of acute febrile diseases in Fiji.

History of arthropod-borne virus infections in French Polynesia

In French Polynesia, arthropod-borne diseases are major public health problems. From the mid-1940s, the four serotypes of dengue virus (DENV-1 to -4) have caused 15 epidemics of variable severity. In 2013, for the first time, a sustained co-circulation of two different DENV serotypes (DENV-1 and -3) was reported. The same year, Zika virus (ZIKV) caused the largest outbreak ever recorded at that time. Severe neurologic complications in adults, including Guillain-Barré syndrome and central nervous system malformations in newborns and foeteuses, such as microcephaly, were reported, and a causal link with ZIKV infection was established. In addition to mosquito-borne transmission, the potential for perinatal, sexual and blood-transfusion transmission of ZIKV was demonstrated. In 2014, chikungunya virus (CHIKV) caused an explosive outbreak. Series of Guillain-Barré syndrome temporally associated with the CHIKV epidemic were reported. Except for DENV, ZIKV and CHIKV, no other arboviruses have been detected so far, but serologic evidence suggested the past silent circulation of Ross River virus. From May 2015 DENV-1 has been the only arbovirus transmitted in French Polynesia, but the reemergence of DENV-2 is highly expected since the detection of two autochthonous cases of DENV-2 infection in June 2018.

Ross River Virus Seroprevalence, French Polynesia, 2014-2015

Ross River virus (RRV), spread by Aedes and Culex mosquitoes, is the most commonly transmitted arbovirus in Australia. A serosurvey of blood donors in French Polynesia during 2011–2013 suggested that RRV circulated without being detected. We report RRV circulation in French Polynesia based on further screening of blood samples collected during 2014–2015.

Global emergence of Alphaviruses that cause arthritis in humans

Arthropod-borne viruses (arboviruses) may cause severe emerging and re-emerging infectious diseases, which pose a significant threat to human and animal health in the world today. These infectious diseases range from mild febrile illnesses, arthritis, and encephalitis to haemorrhagic fevers. It is postulated that certain environmental factors, vector competence, and host susceptibility have a major impact on the ecology of arboviral diseases. Presently, there is a great interest in the emergence of Alphaviruses because these viruses, including Chikungunya virus, O'nyong'nyong virus, Sindbis virus, Ross River virus, and Mayaro virus, have caused outbreaks in Africa, Asia, Australia, Europe, and America. Some of these viruses are more common in the tropics, whereas others are also found in temperate regions, but the actual factors driving Alphavirus emergence and re-emergence remain unresolved. Furthermore, little is known about the transmission dynamics, pathophysiology, genetic diversity, and evolution of circulating viral strains. In addition, the clinical presentation of Alphaviruses may be similar to other diseases such as dengue, malaria, and typhoid, hence leading to misdiagnosis. However, the typical presence of arthritis may distinguish between Alphaviruses and other differential diagnoses. The absence of validated diagnostic kits for Alphaviruses makes even routine surveillance less feasible. For that purpose, this review describes the occurrence, genetic diversity, clinical characteristics, and the mechanisms involving Alphaviruses causing arthritis in humans. This information may serve as a basis for better awareness and detection of Alphavirus-caused diseases during outbreaks and in establishing appropriate prevention and control measures.

Silent Circulation of Ross River Virus in French Polynesia

OBJECTIVES

Ross River is an emerging mosquito-borne disease in the Western Pacific. Ross River virus (RRV) circulation has been sporadically reported in some Pacific Island Countries and Territories but never in French Polynesia. To determine if RRV has circulated locally among the French Polynesian population, we conducted a seroprevalence study on blood donors.

METHODS

Sera of 593 blood donors were collected from July 2011 to October 2013 and tested by ELISA for the presence of RRV-specific Immunoglobulin G (IgG) antibodies.

RESULTS

A total of 204 (34.40%) blood donors were found seropositive for RRV. Among the 132 blood donors that were born in French Polynesia and had never travelled abroad, 56 (42.42%) had RRV-specific IgGs.

DISCUSSION

Our results support the existence of autochthonous RRV transmission and suggest that this pathogen has silently circulated in French Polynesia. These findings raise the question of possible undetected circulation of RRV in other Pacific Island Countries and Territories.