Diagnostic potential of monoclonal antibodies against the capsid protein of chikungunya virus for detection of recent infection

Single-domain antibodies applied as antiviral immunotherapeutics

Viral infections have been the cause of high mortality rates throughout different periods in history. Over the last two decades, outbreaks caused by zoonotic diseases and transmitted by arboviruses have had a significant impact on human health. The emergence of viral infections in different parts of the world encourages the search for new inputs to fight pathologies of viral origin. Antibodies represent the predominant class of new drugs developed in recent years and approved for the treatment of various human diseases, including cancer, autoimmune and infectious diseases. A promising group of antibodies are single-domain antibodies derived from camelid heavy chain immunoglobulins, or VHHs, are biomolecules with nanometric dimensions and unique pharmaceutical and biophysical properties that can be used in the diagnosis and immunotherapy of viral infections. For viral neutralization to occur, VHHs can act in different stages of the viral cycle, including the actual inhibition of infection, to hindering viral replication or assembly. This review article addresses advances involving the use of VHHs in therapeutic propositions aimed to battle different viruses that affect human health.

Dengue-chikungunya infection in the tertiary care hospital of northern India: Cross-sectional latent class cluster analysis in viral infection

Cases of dengue and chikungunya fever are escalating all over India. Both viruses share a common vector, the "Aedes" mosquito. Due to similar clinical symptoms, both the dengue (DENV) and chikungunya (CHIKV) virus can circulate as co-infection. There is very limited data available on dengue-chikungunya co-infection in Uttarakhand, India. The purpose of this study was to determine the seroprevalence of dengue and chikungunya virus infections, as well as their co-infection, in patients presenting with clinical symptoms. Serum samples of clinically suspected patients from the tertiary care hospital of Uttarakhand were collected, and Latent Class Cluster Analysis was performed for clinical profiling. ELISA was performed for DENV and CHIKV. 279 cases were enrolled, out of which 222 (79.5%) came positive for dengue NS1 Ag, 143 (51.2%) for dengue IgM, 98 (35.1%) for IgG followed by 16 (5.7%) of CHIKV IgM, and 4 (1.4%) were NS1 Ag with CHIKV IgM. Among the clinical features, fever (n = 270, 96.8%) was the most common symptom in all suspected dengue and chikungunya cases. Other symptoms like chills (n = 254, 91.0%), arthralgia (n = 241, 86.4%), and headache (n = 240, 86.0%) were present in a significant number. Results showed fewer odds of getting both DENV and CHIKV infection simultaneously, but the risk is still not negligible. This study explores the clinical presentation of the suspected dengue-chikungunya case. The increasing incidence of dengue and chikungunya and their co-infection necessitate the authorities' active surveillance of endemic regions and effective patient care management.

Drug repurposing approach against chikungunya virus: an in vitro and in silico study

The chikungunya virus (CHIKV) is an alphavirus transmitted by Aedes mosquitoes. There are no licenced antivirals or vaccines for treatment or prevention. Drug repurposing approach has emerged as a novel concept to find alternative uses of therapeutics to battle pathogens. In the present study, anti CHIKV activity of fourteen FDA-approved drugs was investigated by in vitro and in silico approaches. Focus-forming unit assay, immunofluorescence test, and quantitative RT-PCR assay were used to assess the in vitro inhibitory effect of these drugs against CHIKV in Vero CCL-81 cells. The findings showed that nine compounds, viz., temsirolimus, 2-fluoroadenine, doxorubicin, felbinac, emetine, lomibuvir, enalaprilat, metyrapone and resveratrol exhibit anti chikungunya activity. Furthermore, in silico molecular docking studies performed by targeting CHIKV structural and non-structural proteins revealed that these drugs can bind to structural protein targets such as envelope protein, and capsid, and non-structural proteins NSP2, NSP3 and NSP4 (RdRp). Findings from in vitro and in silico studies reveal that these drugs can suppress the infection and replication of CHIKV and further in vivo studies followed by clinical trials are warranted.

Development of Highly Sensitive Sandwich ELISA for the Early-Phase Diagnosis of Chikungunya Virus Utilizing rE2-E1 Protein

Introduction

Chikungunya is caused by an alpha virus transmitted to humans by an infected mosquito. Infection is generally considered to be self-limiting and non-critical. Chikungunya infection may be diagnosed by severe joint pain with fever, but it is difficult to diagnose because the symptoms of chikungunya are common to many pathogens, including dengue fever. Diagnosis mainly depends on viral culture, reverse transcriptase polymerase chain reaction (RT-PCR), and IgM ELISA. Early and accurate diagnosis of the virus can be achieved by the application of PCR methods, but the high cost and the need for a thermal cycler restrict the use of such methods. On the other hand, antibody-based IgM ELISA is considered to be inexpensive, but antibodies against chikungunya virus (CHIKV) only develop after 4 days of infection, so it has limited application in the earlier diagnosis of viral infection and the management of patients. Because of these challenges, a simple antigen-based sensitive, specific, and rapid detection method is required for the early and accurate clinical diagnosis of chikungunya.

Methods

The amino acid sequence of CHIKV ectodomain E1 and E2 proteins was analyzed using bioinformatics tools to determine the antigenic residues, particularly the B-cell epitopes and their characteristics. Recombinant E2-E1 CHIKV antigen was used for the development of polyclonal antibodies in hamsters and IgG was purified. Serological tests of 96 CHIKV patients were conducted by antigen-capture ELISA using primary antibodies raised against rCHIKV E2-E1 in hamsters and human anti-CHIKV antibodies.

Results

We observed high specificity and sensitivity, of 100% and 95.8%, respectively, and these values demonstrate the efficiency of the test as a clinical diagnostic tool. There was no cross-reactivity with samples taken from dengue patients.

Discussion

Our simple and sensitive sandwich ELISA for the early-phase detection of CHIKV infection may be used to improve the diagnosis of chikungunya.

Diagnostic accuracy of serological tests for the diagnosis of Chikungunya virus infection: A systematic review and meta-analysis

BACKGROUND

Chikungunya virus (CHIKV) causes febrile illnesses and has always been misdiagnosed as other viral infections, such as dengue and Zika; thus, a laboratory test is needed. Serological tests are commonly used to diagnose CHIKV infection, but their accuracy is questionable due to varying degrees of reported sensitivities and specificities. Herein, we conducted a systematic review and meta-analysis to evaluate the diagnostic accuracy of serological tests currently available for CHIKV.

METHODOLOGY AND PRINCIPAL FINDINGS

A literature search was performed in PubMed, CINAHL Complete, and Scopus databases from the 1st December 2020 until 22nd April 2021. Studies reporting sensitivity and specificity of serological tests against CHIKV that used whole blood, serum, or plasma were included. QUADAS-2 tool was used to assess the risk of bias and applicability, while R software was used for statistical analyses. Thirty-five studies were included in this meta-analysis; 72 index test data were extracted and analysed. Rapid and ELISA-based antigen tests had a pooled sensitivity of 85.8% and 82.2%, respectively, and a pooled specificity of 96.1% and 96.0%, respectively. According to our meta-analysis, antigen detection tests serve as a good diagnostic test for acute-phase samples. The IgM detection tests had more than 90% diagnostic accuracy for ELISA-based tests, immunofluorescence assays, in-house developed tests, and samples collected after seven days of symptom onset. Conversely, low sensitivity was found for the IgM rapid test (42.3%), commercial test (78.6%), and for samples collected less than seven of symptom onset (26.2%). Although IgM antibodies start to develop on day 2 of CHIKV infection, our meta-analysis revealed that the IgM detection test is not recommended for acute-phase samples. The diagnostic performance of the IgG detection tests was more than 93% regardless of the test formats and whether the test was commercially available or developed in-house. The use of samples collected after seven days of symptom onset for the IgG detection test suggests that IgG antibodies can be detected in the convalescent-phase samples. Additionally, we evaluated commercial IgM and IgG tests for CHIKV and found that ELISA-based and IFA commercial tests manufactured by Euroimmun (Lübeck, Germany), Abcam (Cambridge, UK), and Inbios (Seattle, WA) had diagnostic accuracy of above 90%, which was similar to the manufacturers' claim.

CONCLUSION

Based on our meta-analysis, antigen or antibody-based serological tests can be used to diagnose CHIKV reliably, depending on the time of sample collection. The antigen detection tests serve as a good diagnostic test for samples collected during the acute phase (≤7 days post symptom onset) of CHIKV infection. Likewise, IgM and IgG detection tests can be used for samples collected in the convalescent phase (>7 days post symptom onset). In correlation to the clinical presentation of the patients, the combination of the IgM and IgG tests can differentiate recent and past infections.

Arthritogenic Alphavirus Capsid Protein

In the past two decades Old World and arthritogenic alphavirus have been responsible for epidemics of polyarthritis, causing high morbidity and becoming a major public health concern. The multifunctional arthritogenic alphavirus capsid protein is crucial for viral infection. Capsid protein has roles in genome encapsulation, budding and virion assembly. Its role in multiple infection processes makes capsid protein an attractive target to exploit in combating alphaviral infection. In this review, we summarize the function of arthritogenic alphavirus capsid protein, and describe studies that have used capsid protein to develop novel arthritogenic alphavirus therapeutic and diagnostic strategies.

In vitro and in vivo studies reveal α-Mangostin, a xanthonoid from Garcinia mangostana, as a promising natural antiviral compound against chikungunya virus

Background

Chikungunya virus (CHIKV), a serious health problem in several tropical countries, is the causative agent of chikungunya fever. Approved antiviral therapies or vaccines for the treatment or prevention of CHIKV infections are not available. As diverse natural phenolic compounds have been shown to possess antiviral activities, we explored the antiviral activity of α-Mangostin, a xanthanoid, against CHIKV infection.

Methods

The in vitro prophylactic and therapeutic effects of α-Mangostin on CHIKV replication in Vero E6 cells were investigated by administering it under pre, post and cotreatment conditions. The antiviral activity was determined by foci forming unit assay, quantitative RT-PCR and cell-based immune-fluorescence assay. The molecular mechanism of inhibitory action was further proposed using in silico molecular docking studies.

Results

In vitro studies revealed that 8 µM α-Mangostin completely inhibited CHIKV infectivity under the cotreatment condition. CHIKV replication was also inhibited in virus-infected mice. This is the first in vivo study which clearly showed that α-Mangostin is effective in vivo by significantly reducing virus replication in serum and muscles. Molecular docking indicated that α-Mangostin can efficiently interact with the E2–E1 heterodimeric glycoprotein and the ADP-ribose binding cavity of the nsP3 macrodomain.

Conclusions

The findings suggest that α-Mangostin can inhibit CHIKV infection and replication through possible interaction with multiple CHIKV target proteins and might act as a prophylactic/therapeutic agent against CHIKV.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01517-z.

Delineation of an epitope recognized by a chikungunya virus anti-capsid monoclonal antibody on the protease domain using an immuno-informatics approach

The capsid-protein (CP) of chikungunya virus (CHIKV) is reported to generate a primary immune response in infected individuals during disease progression. CP-specific monoclonal antibodies (mAbs) developed in our laboratory, exhibited promising potential in diagnosing recent CHIKV infection in IgM capture ELISA. In this study we focused on the molecular and structural characterization of one such representative mAb ClVE4/D9 to delineate the epitope recognized by it using an immuno-informatics approach. The antigen-antibody interacting residues were found to lie within the dimer interface region of the CP, also predicted as a conformational epitope. This implies that the mAb could interfere during the process of nucleocapsid assembly, ultimately preventing budding and egress of the virus particle. The binding specificity of the mAb highlights the possibility of using this anti-CP antibody for therapeutic or prophylactic treatment against CHIKV.Communicated by Ramaswamy H. Sarma.

Stimulation of dendritic cell functional maturation by capsid protein from chikungunya virus

Objective(s):

Chikungunya virus (ChikV) infection is characterized by persistent infection in joints and lymphoid organs. The ChikV Capsid protein plays an important role in regulating virus replication. In this study, we hypothesized that capsid protein may stimulate dendritic cell (DC) activation and maturation and trigger an inflammatory response in mice.

Materials and Methods:

Mice were intraperitoneally injected with capsid protein and examined for changes in immunophenotype in lymph nodes (LNs). Next, DCs were treated with capsid protein or LPS and then expression of maturation markers, cytokine production, and ability to stimulate CD4⁺ T cells in allo-MLR were analyzed.

Results:

Injection of mice with capsid protein led to recruitment of myeloid cells and increased activation of T lymphocytes in LNs. Importantly, treatment of DCs with capsid protein prolonged the activation of IKB-α and up-regulated the number of CD11c⁺CD86⁺DCs and release of TNF-α and IL-12p70 as well as reducing DC apoptosis, all effects were abolished in the presence of Bay 11-7082. In addition, IL-2 production was higher by CD4⁺ T cells stimulated with capsid-treated as compared with LPS-induced DCs.

Conclusion:

The observations revealed that capsid protein participates in the regulation of NF-κB signaling and maturation of DCs.

Simultaneous detection of IgM antibodies against dengue and chikungunya: Coinfection or cross-reactivity?

Background:

Dengue and chikungunya sharing same mosquito vector are two most important arboviruses circulating in northern India including Delhi and are responsible for frequent outbreaks. Antigen and antibodies detection ELISA kits are the major tool to diagnose these viral illnesses, and are sometimes associated with cross–reactivity, giving a false picture of coinfection, although simultaneous harboring of both the viruses is not uncommon. Various studies have reported coinfection up to 25% from the same region.

Procedure:

This study was conducted in the Department of Microbiology, Maulana Azad Medical College, New Delhi, during the month of September 2016 which included 200 blood samples from clinically suspected cases attending Medicine OPD of associated Lok Nayak Hospital, New Delhi. Diagnosis of dengue and chikungunya was made using NS-1 antigen and IgM MAC ELISA for dengue and IgM MAC ELISA for chikungunya as per manufacturer's instructions.

Results:

Out of 200 suspected cases, 34 (17%) were positive for dengue serology, 77 (38.5%) were positive for chikungunya serology, and 29.9% of positive chikungunya cases were simultaneously affected with dengue. This higher percentage of coinfection might be because of cross-reactivity of the ELISA kits.

Discussion:

India being a hyperendemic region for dengue and chikungunya, frequent outbreaks are quite common. Circulation of both the virus and huge susceptible population are the major causes for frequent outbreaks. Restricting our attention to diagnose one of them is not sufficient, and coinfection further complicates the illness.

Conclusion:

Simultaneous diagnosis of dengue and chikungunya is need of time to diagnose dual infection and prevent complications by starting supportive treatment well in time. Molecular technique if ever possible should be employed whenever the coinfection number is higher than expected to rule out cross-reactivity.

Broad-spectrum monoclonal antibodies against chikungunya virus structural proteins: Promising candidates for antibody-based rapid diagnostic test development

In response to the aggressive global spread of the mosquito-borne chikungunya virus (CHIKV), an accurate and accessible diagnostic tool is of high importance. CHIKV, an arthritogenic alphavirus, comprises three genotypes: East/Central/South African (ECSA), West African (WA), and Asian. A previous rapid immunochromatographic (IC) test detecting CHIKV E1 protein showed promising performance for detection of the ECSA genotype. Unfortunately, this kit exhibited lower capacity for detection of the Asian genotype, currently in circulation in the Americas, reflecting the low avidity of one of the monoclonal antibodies (mAbs) in this IC kit for the E1 protein of the Asian-genotype because of a variant amino acid sequence. To address this shortcoming, we set out to generate a new panel of broad-spectrum mouse anti-CHIKV mAbs using hybridoma technology. We report here the successful generation of mouse anti-CHIKV mAbs targeting CHIKV E1 and capsid proteins. These mAbs possessed broad reactivity to all three CHIKV genotypes, while most of the mAbs lacked cross-reactivity towards Sindbis, dengue, and Zika viruses. Two of the mAbs also lacked cross-reactivity towards other alphaviruses, including O'nyong-nyong, Ross River, Mayaro, Western Equine Encephalitis, Eastern Equine Encephalitis, and Venezuelan Equine Encephalitis viruses. In addition, another two mAbs cross-reacted weakly only with most closely related O'nyong-nyong virus. Effective diagnosis is one of the keys to disease control but to date, no antibody-based rapid IC platform for CHIKV is commercially available. Thus, the application of the mAbs characterized here in the rapid diagnostic IC kit for CHIKV detection is expected to be of great value for clinical diagnosis and surveillance purposes.

Selection and characterization of protective anti-chikungunya virus single domain antibodies

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that causes an arthralgia febrile illness that has affected millions of people on three continents. Previously, neutralizing monoclonal antibodies that have prophylactic and therapeutic activity were found to remove virus in joint tissues, thereby reducing the severity of symptoms in mice and non-human primates. In this study, we sought to develop thermostable small recombinant antibodies against CHIKV for future diagnostic, prophylactic and therapeutic applications. To develop these single domain antibodies (sdAb) a CHIKV immune library was constructed by displaying the consortium of variable heavy domains (VHH) amplified from peripheral white blood cells isolated from llamas immunized with CHIKV virus-like particles (VLPs). Five anti-CHIKV sdAb isolated using bio-panning were evaluated for their affinity and thermal stability. Their ability to detect CHIKV VLPs was demonstrated in both MagPlex- and ELISA- based assays. Finally, the ability of two sdAb, CC3 and CA6, to inhibit CHIKV infection were tested using a plaque reduction and neutralization test (PRNT), yielding PRNT₅₀ values of 0.6 and 45.6 nM, respectively.

Identification of a conserved neutralizing epitope in the G-protein of Chandipura virus

Chandipura virus (CHPV), associated with an encephalitic illness in humans, has caused multiple outbreaks with high mortality in central and western India in recent years. The present study compares surface glycoprotein (G-protein) from prototype and recent outbreak strains using in silico tools and in vitro experiments. In silico epitope predictions (B-cell and T-helper cell) for the sequences, 3D structure prediction and comparison of the G-proteins of the strains: I653514 (Year 1965), CIN0327 (Year 2003) and 148974 (Year 2014) revealed that the CHPV G-protein is stable and antigenic determinants are conserved. A monoclonal antibody developed against strain CIN0327 (named NAbC) was found to neutralize prototype I653514 as well as the currently circulating strain 148974. In silico antigen-antibody interaction studies using molecular docking of predicted structures of NAbC and G-proteins of various CHPV strains led to the identification of a conserved neutralizing epitope in the fusion domain of G-protein, which also contained a putative T-helper peptide. The identification of a conserved neutralizing epitope in domain IV (fusion domain amino acids 53 to 172) of CHPV G-protein is an important finding that may have the scope towards the development of protective targets against CHPV infection.

Evidence of dengue and chikungunya virus co-infection and circulation of multiple dengue serotypes in a recent Indian outbreak

In India, dengue endemic areas overlap with chikungunya-affected areas and both the viruses are transmitted by same vector, Aedes aegypti - thereby increasing opportunity of co-infection by both viruses. Present study was carried out to understand the DENV-CHIKV infection dynamics during recent outbreaks in eastern India (West Bengal state) and its implication on disease manifestations. Blood was collected from 326 symptomatic febrile patients. Patients' serum was subjected to serological diagnosis for presence of anti-dengue-IgM, anti-chikungunya-IgM antibodies and dengue-NS1 antigen by ELISA. Viral RNA was extracted, and presence of dengue virus (DENV) and chikungunya virus (CHIKV) genome, their viral load (VL), and serotype among infected patients' plasma was determined by real-time qRT-PCR. Statistical analysis was performed by using EPI INFO software. DENV and CHIKV were detected in 54% and 33% of symptomatic patients respectively, among whom 23% were harboring both viruses. WHO classified warning signs were detected among 64% DENV patients and 61% DENV-CHIKV double-infected patients. Patients with warning signs always had much higher DEN VL than those without warning signs. Hemorrhagic manifestation and abdominal pain was found in significantly higher frequency among patients with high dengue VL (>10,000 copies/ml). DENV2 was the most predominant serotype among monotypic dengue patients, whereas DENV2-DENV4 combination was most prevalent among patients infected with dual dengue serotypes. This study indicated that DENV-CHIKV double infection and high dengue VL contributed towards severe disease manifestations among infected patients. DENV2 and DENV2-DENV4 combination were the most prevalent serotype(s) found in current outbreak.