Robustness of Serologic Investigations for Chikungunya and Mayaro Viruses following Coemergence

Potential Serological Misdiagnosis of Barmah Forest Virus and Ross River Virus Diseases as Chikungunya Virus Infections in Australia: Comparison of ELISA with Neutralization Assay Results

To evaluate the frequency of errors in the diagnosis of medical laboratory-diagnosed Chikungunya virus (CHIKV) infections in Australia, we studied 42 laboratory-diagnosed CHIKV serum samples from one Queensland medical laboratory by ELISA IgG/IgM and measured the specific neutralization antibodies (Nab) against Barmah Forest virus (BFV), CHIKV and Ross River virus (RRV). The sero-positivity rates for the sera were as follows: anti-BFV IgG+ 19% (8/42), IgM+ 2.4% (1/42) and Nab+ 16.7% (7/42); anti-CHIKV IgG+ 90.5% (38/42), IgM+ 21.4% (9/42) and Nab+ 90.5% (38/42); anti-RRV IgG+ 88.1% (37/42), IgM+ 28.6% (12/42) and Nab+ 83.2% (35/42), respectively. Among the samples with multiple antibody positivity, 2.4% (1/42) showed triple ELISA IgM+, and 14.3% (6/42) exhibited double IgM RRV+CHIKV+; 9.5% (4/42) showed triple IgG+, 76.2% (32/42) displayed double IgG RRV+CHIKV+, 4.8% (2/42) showed IgG BFV+RRV+ and 4.8% (2/42) showed IgG BFV++CHIKV+; and 9.5% (4/42) showed triple Nab+ and 69% (29/42) exhibited double Nab RRV+CHIKV+, respectively. Our analysis of the single-virus infection control Nab results suggested no cross-neutralization between RRV and BFV, and only mild cross-neutralization between CHIKV and RRV, BFV and CHIKV, all with a ≥4-fold Nab titre ratio difference between the true virus infection and cross-reactivity counterpart virus. Subsequently, we re-diagnosed these 42 patients as 1 BFV+, 8 CHIKV+ and 23 RRV+ single-virus infections, along with five RRV+/BFV+ and four RRV+/CHIKV+ double infections, and one possible RRV+/BFV+ or RRV+CHIKV+, respectively. These findings suggests that a substantial proportion of medically attended RRV and BFV infections were misdiagnosed as CHIKV infections, highlighting the imperative need for diagnostic laboratory tests capable of distinguishing between CHIKV infections and actively co-circulating RRV and BFV. For a correct diagnosis, it is crucial to consider reliable diagnostic methods such as the neutralization assay to exclude RRV and BFV.

A geopositioned and evidence-graded pan-species compendium of Mayaro virus occurrence

Mayaro Virus (MAYV) is an emerging health threat in the Americas that can cause febrile illness as well as debilitating arthralgia or arthritis. To better understand the geographic distribution of MAYV risk, we developed a georeferenced database of MAYV occurrence based on peer-reviewed literature and unpublished reports. Here we present this compendium, which includes both point and polygon locations linked to occurrence data documented from its discovery in 1954 until 2022. We describe all methods used to develop the database including data collection, georeferencing, management and quality-control. We also describe a customized grading system used to assess the quality of each study included in our review. The result is a comprehensive, evidence-graded database of confirmed MAYV occurrence in humans, non-human animals, and arthropods to-date, containing 262 geo-positioned occurrences in total. This database - which can be updated over time - may be useful for local spill-over risk assessment, epidemiological modelling to understand key transmission dynamics and drivers of MAYV spread, as well as identification of major surveillance gaps.

Serological and molecular evidence of chikungunya virus infection among febrile outpatients seeking healthcare in Northern Malawi

Introduction: Despite global evidence of chikungunya fever (CHIKF) in humans that is caused by chikungunya virus (CHIKV), little is known about the occurrence of CHIKF in Malawi. This study was conducted to determine the seroprevalence of CHIKF and to molecularly confirm the presence of CHIKV ribonucleic acid (RNA) among febrile outpatients seeking health care at Mzuzu Central Hospital in the Northern Region of Malawi. Methods: Enzyme-immunosorbent assay (ELISA) was used to detect the presence or absence of specific antibodies against CHIKV. Reversetranscription polymerase chain reaction (RT-PCR) was conducted on randomly selected anti-CHIKV IgM-positive samples to detect CHIKV RNA. Results: Out of 119 CHIKF suspected samples analyzed, 73 tested positive for anti-CHIKV IgM antibodies, with an overall seroprevalence of 61.3%. Most of the CHIKV infected individuals presented with joint pain, abdominal pain, vomiting and nose bleeding with seroprevalence of 45.2%, 41.1%, 16.4% and 12.3%, respectively. All the randomly selected samples that were positive for CHIKV anti-IgM by ELISAhad detectable CHIKV RNA by RT-PCR. Conclusion: The presence of anti-CHIKV IgM antibodies suggests the presence of recent CHIKV infection. We therefore recommend for the inclusion of CHIKF as the differential diagnosis in febrile ill patients in Mzuzu city, Malawi.

Chikungunya fever

Chikungunya virus is widespread throughout the tropics, where it causes recurrent outbreaks of chikungunya fever. In recent years, outbreaks have afflicted populations in East and Central Africa, South America and Southeast Asia. The virus is transmitted by Aedes aegypti and Aedes albopictus mosquitoes. Chikungunya fever is characterized by severe arthralgia and myalgia that can persist for years and have considerable detrimental effects on health, quality of life and economic productivity. The effects of climate change as well as increased globalization of commerce and travel have led to growth of the habitat of Aedes mosquitoes. As a result, increasing numbers of people will be at risk of chikungunya fever in the coming years. In the absence of specific antiviral treatments and with vaccines still in development, surveillance and vector control are essential to suppress re-emergence and epidemics.

Understanding the Biology and Immune Pathogenesis of Chikungunya Virus Infection for Diagnostic and Vaccine Development

Chikungunya virus, the causative agent of chikungunya fever, is generally characterized by the sudden onset of symptoms, including fever, rash, myalgia, and headache. In some patients, acute chikungunya virus infection progresses to severe and chronic arthralgia that persists for years. Chikungunya infection is more commonly identified in tropical and subtropical regions. However, recent expansions and epidemics in the temperate regions have raised concerns about the future public health impact of chikungunya diseases. Several underlying factors have likely contributed to the recent re-emergence of chikungunya infection, including urbanization, human travel, viral adaptation to mosquito vectors, lack of effective control measures, and the spread of mosquito vectors to new regions. However, the true burden of chikungunya disease is most likely to be underestimated, particularly in developing countries, due to the lack of standard diagnostic assays and clinical manifestations overlapping with those of other endemic viral infections in the regions. Additionally, there have been no chikungunya vaccines available to prevent the infection. Thus, it is important to update our understanding of the immunopathogenesis of chikungunya infection, its clinical manifestations, the diagnosis, and the development of chikungunya vaccines.

Arbovirus Antibody Seroprevalence in the Human Population from Cauca, Colombia

Several arboviruses have emerged or reemerged into the New World during the past several decades, causing outbreaks of significant proportion. In particular, the outbreaks of Dengue virus (DENV), Zika virus, and Chikungunya virus (CHIKV) have been explosive and unpredictable, and have led to significant adverse health effects. These viruses are considered the leading cause of acute undifferentiated febrile illnesses in Colombia. However, Venezuelan equine encephalitis virus (VEEV) is endemic in Colombia, and arboviruses such as the Mayaro virus (MAYV) and the Oropouche virus (OROV) cause febrile illnesses in neighboring countries. Yet, evidence of human exposure to MAYV and OROV in Colombia is scarce. In this study, we conducted a serosurvey study in healthy individuals from the Cauca Department in Colombia. We assessed the seroprevalence of antibodies against multiple arboviruses, including DENV serotype 2, CHIKV, VEEV, MAYV, and OROV. Based on serological analyses, we found that the overall seroprevalence for DENV serotype 2 was 30%, 1% for MAYV, 2.6% for CHIKV, 4.4% for VEEV, and 2% for OROV. This study provides evidence about the circulation of MAYV and OROV in Colombia, and suggests that they-along with VEEV and CHIKV-might be responsible for cases of acute undifferentiated febrile illnesses that remain undiagnosed in the region. The study results also highlight the need to strengthen surveillance programs to identify outbreaks caused by these and other vector-borne pathogens.

Comparison of Neutralizing Antibody Response Kinetics in Patients with Hand, Foot, and Mouth Disease Caused by Coxsackievirus A16 or Enterovirus A71: A Longitudinal Cohort Study of Chinese Children, 2017-2019

Hand, foot, and mouth disease (HFMD), which is mainly caused by coxsackievirus A16 (CVA16) or enterovirus A71 (EV-A71), poses a serious threat to children's health. However, the long-term dynamics of the neutralizing Ab (NAb) response and ideal paired-serum sampling time for serological diagnosis of CVA16-infected HFMD patients were unclear. In this study, 336 CVA16 and 253 EV-A71 PCR-positive HFMD inpatients were enrolled and provided 452 and 495 sera, respectively, for NAb detection. Random-intercept modeling with B-spline was conducted to characterize NAb response kinetics. The NAb titer of CVA16 infection patients was estimated to increase from negative (2.1, 95% confidence interval [CI]: 1.4-3.3) on the day of onset to a peak of 304.8 (95% CI: 233.4-398.3) on day 21 and then remained >64 until 26 mo after onset. However, the NAb response level of EV-A71-infected HFMD patients was much higher than that of CVA16-infected HFMD patients throughout. The geometric mean titer was significantly higher in severe EV-A71-infected patients than in mild patients, with a 2.0-fold (95% CI: 1.4-3.2) increase. When a 4-fold rise in titer was used as the criterion for serological diagnosis of CVA16 and EV-A71 infection, acute-phase serum needs to be collected at 0-5 d, and the corresponding convalescent serum should be respectively collected at 17.4 (95% CI: 9.6-27.4) and 24.4 d (95% CI: 15.3-38.3) after onset, respectively. In conclusion, both CVA16 and EV-A71 infection induce a persistent humoral immune response but have different NAb response levels and paired-serum sampling times for serological diagnosis. Clinical severity can affect the anti-EV-A71 NAb response.

Development of Viral-Vectored Vaccines and Virus Replicon Particle-Based Neutralisation Assay against Mayaro Virus

Mayaro virus (MAYV) is an emerging alphavirus causing acute febrile illness associated with chronic polyarthralgia. Although MAYV is currently restricted to tropical regions in South America around the Amazon basin, it has the potential to spread globally by Aedes species mosquitoes. In addition, there are currently no specific therapeutics or licenced vaccines against MAYV infection. We have previously shown that an adenovirus based Mayaro vaccine (ChAdOx1 May) was able to provide full protection against MAYV challenge in vaccinated A129 mice and induced high neutralising antibody titres. In this study, we have constructed a replication deficient simian adenovirus (ChAdOx2) and a Modified Ankara Virus (MVA) based vaccine expressing the MAYV structural cassette (sMAYV) similar to ChAdOx1 May, and characterised recombinant MAYV E2 glycoprotein expressed in a mammalian system for immune monitoring. We demonstrate that ChAdOx2 May was able to induce high antibody titres similar to ChAdOx1 May, and MVA May was shown to be an effective boosting strategy following prime vaccination with ChAdOx1 or ChAdOx2 May. In order to measure MAYV neutralising ability, we have developed a virus replicon particle-based neutralisation assay which effectively detected neutralising antibodies against MAYV. In summary, our study indicates the potential for further clinical development of the viral vectored MAYV vaccines against MAYV infections.

Incidence of Sindbis Virus in Hospitalized Patients With Acute Fevers of Unknown Cause in South Africa, 2019-2020

BACKGROUND

Sindbis virus (SINV) is a mosquito-borne alphavirus that is widely distributed worldwide. Little is known about the febrile and neurological disease burden due to SINV in South Africa.

PATIENTS AND METHODS

Clinical samples of patients with acute febrile disease of unknown cause (AFDUC) were collected through the African Network for Improved Diagnostics, Epidemiology and Management of Common Infectious Agents at three sentinel hospital surveillance sites in South Africa. In total, 639 patients were screened using a PCR-based macroarray that can simultaneously detect nucleic acids of 30 pathogens, including SINV, from January 2019 to December 2020. Serum samples were randomly selected from the arbovirus season (January-June) and also screened with a commercial indirect immunofluorescence assay for anti-SINV IgM. In addition, 31 paired cerebrospinal fluid (CSF) specimens from the same patients were screened for IgM. Micro-neutralization assays were performed on all IgM-positive samples.

RESULTS

None of the specimens tested positive for SINV by molecular screening; however, 38/197 (19.0%) samples were positive for SINV-specific IgM. A total of 25/38 (65.8%) IgM-positive samples tested positive for SINV-neutralizing antibodies, giving an overall incidence of 12.7%. Furthermore, 2/31 (6.5%) CSF specimens tested positive for IgM but were negative for neutralizing antibodies. There was a higher incidence of SINV-positive cases in Mpumalanga (26.0%) than Gauteng province (15.0%). The most significant months for IgM-positive cases were April 2019 (OR = 2.9, p < 0.05), and May 2020 (OR = 7.7, p < 0.05).

CONCLUSION

SINV or a closely related virus contributed to 12.7% of AFDUC cases in hospitalized patients during the late summer and autumn months in South Africa and was significantly associated with arthralgia, meningitis, and headaches.

High SARS-CoV-2 Seroprevalence in Rural Peru, 2021: a Cross-Sectional Population-Based Study

Latin America has been severely affected by the COVID-19 pandemic. The COVID-19 burden in rural settings in Latin America is unclear. We performed a cross-sectional, population-based, random-selection SARS-CoV-2 serologic study during March 2021 in the rural population of San Martin region, northern Peru. In total, 563 persons from 288 houses across 10 provinces were enrolled, reaching 0.2% of the total rural population of San Martin. Screening for SARS-CoV-2 IgG antibodies was done using a chemiluminescence immunoassay (CLIA), and reactive sera were confirmed using a SARS-CoV-2 surrogate virus neutralization test (sVNT). Validation of the testing algorithm using prepandemic sera from two regions of Peru showed false-positive results in the CLIA (23/84 sera; 27%) but not in the sVNT, highlighting the pitfalls of SARS-CoV-2 antibody testing in tropical regions and the high specificity of the two-step algorithm used in this study. An overall 59.0% seroprevalence (95% confidence interval [CI], 55 to 63%) corroborated intense SARS-CoV-2 spread in San Martin. Seroprevalence rates between the 10 provinces varied from 41.3 to 74.0% (95% CI, 30 to 84%). Higher seroprevalence was not associated with population size, population density, surface area, mean altitude, or poverty index in Spearman correlations. Seroprevalence and reported incidence diverged substantially between provinces, suggesting regional biases of COVID-19 surveillance data. Potentially, limited health care access due to environmental, economic, and cultural factors might lead to undetected infections in rural populations. Additionally, test avoidance to evade mandatory quarantine might affect rural regions more than urban regions. Serologic diagnostics should be pursued in resource-limited settings to inform country-level surveillance and vaccination strategies and to support control measures for COVID-19.

IMPORTANCE Latin America is a global hot spot of the COVID-19 pandemic. Serologic studies in Latin America have been mostly performed in urban settings. Rural populations comprise 20% of the total Latin American population. Nevertheless, information on COVID-19 spread in rural settings is scarce. Using a representative population-based seroprevalence study, we detected a high seroprevalence in rural populations in San Martin, northern Peru, in 2021, reaching 41 to 74%. However, seroprevalence and reported incidence diverged substantially between regions, potentially due to limited health care access or test avoidance due to mandatory quarantine. Our results suggest that rural populations are highly affected by SARS-CoV-2 even though they are sociodemographically distinct from urban populations and that highly specific serological diagnostics should be performed in resource-limited settings to support public health strategies of COVID-19 control.

Emergent Arboviruses: A Review About Mayaro virus and Oropouche orthobunyavirus

Arthropod-borne viruses have a significant impact on public health worldwide, and their (re) emergence put aside the importance of other circulating arboviruses. Therefore, this scoping review aims to identify and characterize the literature produced in recent years, focusing on aspects of two arboviruses: Mayaro virus and Oropouche orthobunyavirus. The Mayaro and Oropouche viruses were isolated for the first time in Trinidad and Tobago in 1954 and 1955, respectively, and have more recently caused numerous outbreaks. In addition, they have been incriminated as candidate diseases for human epidemics. These viruses have been drawing the attention of public health authorities worldwide following recent outbreaks. To determine the global epidemiological profile of these viruses, we used the Dimensions Database, which contains more than 100 million publications. In general, we identified 327 studies published from 1957 to 2020 for Mayaro virus, and 152 studies published from 1961 to 2020 for Oropouche orthobunyavirus. Interestingly, we observed that Mayaro and Oropouche had a significant increase in the number of publications in recent years. Thus, this comprehensive review will be helpful to guide future research based on the identified knowledge gaps.

Near-germline human monoclonal antibodies neutralize and protect against multiple arthritogenic alphaviruses

Arthritogenic alphaviruses are globally distributed, mosquito-transmitted viruses that cause rheumatological disease in humans and include Chikungunya virus (CHIKV), Mayaro virus (MAYV), and others. Although serological evidence suggests that some antibody-mediated heterologous immunity may be afforded by alphavirus infection, the extent to which broadly neutralizing antibodies that protect against multiple arthritogenic alphaviruses are elicited during natural infection remains unknown. Here, we describe the isolation and characterization of MAYV-reactive alphavirus monoclonal antibodies (mAbs) from a CHIKV-convalescent donor. We characterized 33 human mAbs that cross-reacted with CHIKV and MAYV and engaged multiple epitopes on the E1 and E2 glycoproteins. We identified five mAbs that target distinct regions of the B domain of E2 and potently neutralize multiple alphaviruses with differential breadth of inhibition. These broadly neutralizing mAbs (bNAbs) contain few somatic mutations and inferred germline-revertants retained neutralizing capacity. Two bNAbs, DC2.M16 and DC2.M357, protected against both CHIKV- and MAYV-induced musculoskeletal disease in mice. These findings enhance our understanding of the cross-reactive and cross-protective antibody response to human alphavirus infections.

Performance assessment of a multi-epitope chimeric antigen for the serological diagnosis of acute Mayaro fever

Mayaro virus (MAYV), which causes mayaro fever, is endemic to limited regions of South America that may expand due to the possible involvement of Aedes spp. mosquitoes in its transmission. Its effective control will require the accurate identification of infected individuals, which has been restricted to nucleic acid-based tests due to similarities with other emerging members of the Alphavirus genus of the Togaviridae family; both in structure and clinical symptoms. Serological tests have a more significant potential to expand testing at a reasonable cost, and their performance primarily reflects that of the antigen utilized to capture pathogen-specific antibodies. Here, we describe the assembly of a synthetic gene encoding multiple copies of antigenic determinants mapped from the nsP1, nsP2, E1, and E2 proteins of MAYV that readily expressed as a stable chimeric protein in bacteria. Its serological performance as the target in ELISAs revealed a high accuracy for detecting anti-MAYV IgM antibodies. No cross-reactivity was observed with serum from seropositive individuals for dengue, chikungunya, yellow fever, Zika, and other infectious diseases as well as healthy individuals. Our data suggest that this bioengineered antigen could be used to develop high-performance serological tests for MAYV infections.

Mayaro virus detection in the western region of Pará state, Brazil

INTRODUCTION

Mayaro virus (MAYV) was found in Pará state, Brazil, in 1955. Since then, sporadic outbreaks have occurred in different regions of the country.

METHODS:

Serum sample were collected from 49 individuals in 2016 and were initially tested for dengue virus (DENV) by real-time (RT) polymerase chain reaction (PCR). DENV-negative samples were tested for MAYV and Oropouche virus (OROV) by multiplexed RT quantitative PCR.

RESULTS:

All samples were negative for DENV and OROV, but MAYV was detected in four samples.

CONCLUSIONS:

Differential diagnoses of acute febrile syndrome are required, especially in regions where several arboviruses with similar clinical manifestations are endemic.

A silent public health threat: emergence of Mayaro virus and co-infection with Dengue in Peru

OBJECTIVE

To describe frequency and clinical characteristics of MAYV infection in Piura, as well as the association of this pathogen with DENV.

RESULTS

A total of 86/496 (17.3%) cases of MAYV were detected, of which 54 were MAYV mono-infection and 32 were co-infection with DENV, accounting for 10.9% and 6.4%, respectively. When evaluating monoinfection by MAYV the main groups were 18-39 and 40-59 years old, with 25.9% and 20.4% respectively. Co-infections were more common in the age group 18-39 and those > 60 years old, with 34.4% and 21.9%, respectively. The most frequent clinical presentation were headaches (94.4%, 51/54) followed by arthralgias (77.8%, 42/54). During the 8-month study period the most cases were identified in the months of May (29.1%) and June (50.0%).

Mayaro Virus Pathogenesis and Transmission Mechanisms

Mayaro virus (MAYV), isolated for the first time in Trinidad and Tobago, has captured the attention of public health authorities worldwide following recent outbreaks in the Americas. It has a propensity to be exported outside its original geographical range, because of the vast distribution of its vectors. Moreover, most of the world population is immunologically naïve with respect to infection with MAYV which makes this virus a true threat. The recent invasion of several countries by Aedesalbopictus underscores the risk of potential urban transmission of MAYV in both tropical and temperate regions. In humans, the clinical manifestations of MAYV disease range from mild fever, rash, and joint pain to arthralgia. In the absence of a licensed vaccine and clinically proven therapeutics against Mayaro fever, prevention focuses mainly on household mosquito control. However, as demonstrated for other arboviruses, mosquito control is rather inefficient for outbreak management and alternative approaches to contain the spread of MAYV are therefore necessary. Despite its strong epidemic potential, little is currently known about MAYV. This review addresses various aspects of MAYV, including its epidemiology, vector biology, mode of transmission, and clinical complications, as well as the latest developments in MAYV diagnosis.