Antibody response patterns in chikungunya febrile phase predict protection versus progression to chronic arthritis

Deep mutationally scanned CHIKV E3/E2 virus library maps viral amino acid preferences and predicts viral escape mutants of neutralizing CHIKV antibodies

As outbreaks of chikungunya virus (CHIKV), a mosquito-borne alphavirus, continue to present public health challenges, additional research is needed to generate protective and safe vaccines and effective therapeutics. Prior research established a role for antibodies in mediating protection against CHIKV infection, and the early appearance of CHIKV-specific IgG or IgG neutralizing antibodies protects against progression to chronic CHIKV disease in humans. However, the importance of epitope specificity for these protective antibodies and how skewed responses contribute to the development of acute and chronic CHIKV-associated joint disease remains poorly understood. Here, we describe the deep mutational scanning of one of the dominant targets of neutralizing antibodies during CHIKV infection, the E3/E2 (also known as p62) glycoprotein complex, to simultaneously test thousands of p62 mutants against selective pressures of interest in a high throughput manner. Characterization of the virus library revealed achievement of high diversity while also selecting out nonfunctional virus variants. Furthermore, this study provides evidence that this virus library system can comprehensively map sites critical for the neutralization function of antibodies of both known and unknown p62 domain specificities.IMPORTANCEChikungunya virus (CHIKV) is a mosquito-borne alphavirus of global health concern that causes debilitating acute and chronic joint disease. Prior studies established a critical role for antibodies in protection against CHIKV infection. Here, we describe the generation of a high-throughput, functional virus library capable of identifying critical functional sites for anti-viral antibodies. This new tool can be used to better understand antibody responses associated with distinct CHIKV infection outcomes and could contribute to the development of efficacious vaccines and antibody-based therapeutics.

Deep mutationally scanned (DMS) CHIKV E3/E2 virus library maps viral amino acid preferences and predicts viral escape mutants of neutralizing CHIKV antibodies

As outbreaks of chikungunya virus (CHIKV), a mosquito-borne alphavirus, continue to present public health challenges, additional research is needed to generate protective and safe vaccines and effective therapeutics. Prior research has established a role for antibodies in mediating protection against CHIKV infection, and the early appearance of CHIKV-specific IgG or IgG neutralizing antibodies protects against progression to chronic CHIKV disease in humans. However, the importance of epitope specificity for these protective antibodies and how skewed responses contribute to development of acute and chronic CHIKV-associated joint disease remains poorly understood. Here, we describe the deep mutational scanning of one of the dominant targets of neutralizing antibodies during CHIKV infection, the E3/E2 (also known as p62) glycoprotein complex, to simultaneously test thousands of p62 mutants against selective pressures of interest in a high throughput manner. Characterization of the virus library revealed achievement of high diversity while also selecting out non-functional virus variants. Furthermore, this study provides evidence that this virus library system can comprehensively map sites critical for the neutralization function of antibodies of both known and unknown p62 domain specificities.

Acute Immunological Profile and Prognostic Biomarkers of Persistent Joint Pain in Chikungunya Fever: A Systematic Review

Chikungunya virus infection (CHIKV) increases the risk of persistent arthralgia; however, there is no consistent evidence regarding prognostic biomarkers of progression to chronic arthropathy. This systematic review provides an overview of currently available literature about the potential role of the acute immunologic response in predicting long-term joint pain in patients with a diagnosis of CHIKV. We searched for observational studies using the terms "chikungunya," "cytokines," "biomarkers," and "joint pain" in PubMed/MEDLINE, LILACS, Cochrane Library Plus, and SCOPUS databases, restricting to articles published in English and up to April 2024. PROSPERO registration number: CRD42021279400. Thirty-eight studies were selected for qualitative synthesis with a maximum duration from diagnosis to clinical evaluation of 60 months. The sample sizes ranged from 8 to 346 participants (age range: 0-90 years). We identified an immunologic profile during the acute phase of CHIKV that includes increased levels of proinflammatory cytokines (IFN-α, IFN-γ, IL-2R, IL-6, IL-7, and IL-8), anti-inflammatory cytokines (IL-1Ra and IL-4), chemokines (MCP-1, MIG, and IP-10) and growth factors (VEGF and G-CSF). Only one out of two studies reported differences in cytokine levels during the acute phase, predicting persistent joint pain at 20 months of follow-up. Also, persistence of anti-CHIKV IgG seemed to be a potential prognostic marker. The evidence suggests the existence of an inflammatory response in the acute phase of CHIKV that persists during its chronic phase; however, there is no unequivocal candidate set of biomarkers of progression toward long-term articular sequelae.

Seropositivity of Chikungunya in Hospital Setting, India: A Systematic Review and Meta-Analysis

Backround

Information about the chikungunya disease burden by age groups and geographic distribution is necessary to guide appropriate control measures. With this, we conducted a systematic review and meta-analysis to estimate the disease burden of chikungunya fever in India.

Material and Methods

We conducted this systematic review according to the Cochrane Collaboration guidelines. We retrieved relevant articles from PubMed and a free online search. Two investigators screened titles and abstracts and extracted data from the relevant articles. Our primary outcome is the proportion of laboratory-confirmed Chikungunya fever among clinically suspected patients. We used a random effect model to estimate the pooled proportion of Chikungunya fever.

Result

A total of 20 articles were included in the quantitative syntheses. The pooled proportion of laboratory-confirmed chikungunya fever from 20 studies estimated using the random effects model is 24% (95%CI: 15-34%). We found the pooled proportion in the southern region was 35% (95%CI: 4-66%), 28% (95%CI: 3-58%) in the western region, 24% (95%CI: 1-48%) in the eastern region, 20% (95%CI: 12-29%) in the northern region, and 4% (95%CI: 1-6%) in North-eastern region.

Conclusion

This review emphasizes the need to strengthen the surveillance of disease burden using multiple diagnostic tests and the need for an appropriate molecular diagnostic for early detection of the chikungunya virus.

Serological and Molecular Epidemiology of Chikungunya Virus Infection in Vietnam, 2017-2019

Chikungunya fever is an acute febrile illness caused by the chikungunya virus (CHIKV), which is transmitted by Aedes mosquitoes. Since 1965, only a few studies with limited scope have been conducted on CHIKV in Vietnam. Thus, this study aimed to determine the seroprevalence and molecular epidemiology of CHIKV infection among febrile patients in Vietnam from 2017 to 2019. A total of 1063 serum samples from 31 provinces were collected and tested for anti-CHIKV IgM and IgG ELISA. The 50% focus reduction neutralization test (FRNT50) was used to confirm CHIKV-neutralizing antibodies. Quantitative real-time RT-PCR (RT-qPCR) was performed to confirm the presence of the CHIKV genome. The results showed that 15.9% (169/1063) of the patients had anti-CHIKV IgM antibodies, 20.1% (214/1063) had anti-CHIKV IgG antibodies, 10.4% (111/1063) had CHIKV-neutralizing antibodies, and 27.7% (130/469) of the samples were positive in RT-qPCR analysis. The E1 CHIKV genome sequences were detected among the positive RT-qPCR samples. Our identified sequences belonged to the East/Central/South/African (ECSA) genotype, which has been prevalent in Vietnam previously, suggesting CHIKV has been maintained and is endemic in Vietnam. This study demonstrates a high prevalence of CHIKV infection in Vietnam and calls for an annual surveillance program to understand its impact.

Chikungunya virus antepartum transmission and abnormal infant outcomes in Nigeria

Chikungunya virus (CHIKV) has become a global public health concern since the reemergence of the Indian Ocean lineage and expansion of the Asian genotype. CHIKV infection causes acute febrile illness, rash, and arthralgia and during pregnancy may affect both mothers and infants. The mother-to-child transmission (MTCT) of CHIKV in Africa remains understudied. We screened 1006 pregnant women at two clinics in Nigeria between 2019 and 2022 and investigated the prevalence and MTCT of CHIKV. Of the 1006, 119 tested positive for CHIKV IgM, of which 36 underwent detailed laboratory tests. While none of the IgM reactive samples were RT-PCR positive, 14 symptomatic pregnant women were confirmed by CHIKV neutralization test. Twelve babies were followed with 8 normal and 4 abnormal outcomes, including stillbirth, cleft lip/palate with microcephaly, preterm delivery, polydactyly with sepsis and jaundice. CHIKV IgM testing identified 3 antepartum transmissions, further studies will determine its impact in antepartum infection.

An Overview of Indian Biomedical Research on the Chikungunya Virus with Particular Reference to Its Vaccine, an Unmet Medical Need

Chikungunya virus (CHIKV) is an infectious agent spread by mosquitos, that has engendered endemic or epidemic outbreaks of Chikungunya fever (CHIKF) in Africa, South-East Asia, America, and a few European countries. Like most tropical infections, CHIKV is frequently misdiagnosed, underreported, and underestimated; it primarily affects areas with limited resources, like developing nations. Due to its high transmission rate and lack of a preventive vaccine or effective treatments, this virus poses a serious threat to humanity. After a 32-year hiatus, CHIKV reemerged as the most significant epidemic ever reported, in India in 2006. Since then, CHIKV-related research was begun in India, and up to now, more than 800 peer-reviewed research papers have been published by Indian researchers and medical practitioners. This review gives an overview of the outbreak history and CHIKV-related research in India, to favor novel high-quality research works intending to promote effective treatment and preventive strategies, including vaccine development, against CHIKV infection.

Virological, Serological and Clinical Analysis of Chikungunya Virus Infection in Thai Patients

From 2018 to 2020, the Chikungunya virus (CHIKV) outbreak re-emerged in Thailand with a record of more than 10,000 cases up until the end of 2020. Here, we studied acute CHIKV-infected patients who had presented to the Bangkok Hospital for Tropical Diseases from 2019 to 2020 by assessing the relationship between viral load, clinical features, and serological profile. The results from our study showed that viral load was significantly high in patients with fever, headache, and arthritis. We also determined the neutralizing antibody titer in response to the viral load in patients, and our data support the evidence that an effective neutralizing antibody response against the virus is important for control of the viral load. Moreover, the phylogenetic analysis revealed that the CHIKV strains we studied belonged to the East, Central, and Southern African (ECSA) genotype, of the Indian ocean lineage (IOL), and possessed E1-K211E and E1-I317V mutations. Thus, this study provides insight for a better understanding of CHIKV pathogenesis in acute infection, along with the genomic diversity of the current CHIKV strains circulating in Thailand.

Immunoglobulin G Subclass Response After Chikungunya Virus Infection

Various vaccines are under development to prevent chikungunya (CHIKV) infection. For the assessment of the CHIKV vaccine-induced antibody response, it is extremely important to understand antibody response after the infection has occurred. Previously, we assessed IgG response in samples from healthy donors using I-CHIKV and found that IgG1 was the predominant subclass induced after CHIKV infection followed by IgG4. However, IgG3 subclass induction is reported in serum samples from patients with acute CHIKV infection. Therefore, in this study, we evaluated serum/plasma from samples of patients with acute CHIKV infection for the presence of IgG and IgG subclasses against I-CHIKV and recombinant E2 protein (rE2). Out of 44 samples that were positive against I-CHIKV, 43 were found reactive against rE2. The positivity of IgG1 either alone or together with other IgG subclasses using I-CHIKV was 89% samples, while 86% samples were positive using rE2. High titers of IgG1 are obtained with I-CHIKV (67%), while raised IgG4 levels are detected using rE2p (72%) in the samples that are positive for both these subclasses. Testing of 22 samples for neutralizing antibodies revealed 100% IgG1 positivity and neutralizing antibodies in 21, 1 sample negative for both. Overall, these data will be useful in assessing IgG subclass-specific CHIKV neutralization and response after CHIKV immunization.

Age-Dependent Evaluation of Immunoglobulin G Response after Chikungunya Virus Infection

Current chikungunya antibody prevalence and titers are likely to differ based on exposure rates before the 2006 reemergence. For vaccine usage, such data are of immense importance. This study addresses age-stratified IgG titers and its subtypes in Pune, India, endemic for the disease. One hundred seventy serum pools (791 individuals with prior chikungunya exposure, age stratified) from exposed and 15 samples from acute disease phase were screened. Inactivated chikungunya virus (CHIKV)-based indirect ELISA was used to determine anti-CHIKV-IgG and its subtypes. Neutralizing antibody titers (plaque reduction neutralization test [PRNT]) were compared with binding antibody titers (ELISA). Anti-CHIKV-IgG titers along with IgG1 and IgG4 increased till the age-group of 11-15 years and remained comparable thereafter till > 65 years. IgG1 was the predominant IgG subtype detected in all the pools, whereas IgG4 was present in 151/170 pools. Strong correlation of IgG1 was obtained with CHIKV-PRNT50 titers. None of the sample had anti-CHIKV-IgG2, whereas five pools had IgG3 antibody. In the acute-phase serum sample, IgG1 was present in all the samples, whereas IgG4 was present in 8/15 samples. IgG4 was predominant in four samples. During acute phase and at different times postinfection, IgG1 circulated in high titers followed by IgG4. Higher antibody titers in adults reflect reexposures. The data will prove useful in assessing immune response to CHIKV vaccine.