Atypical Chikungunya Virus Infections in Immunocompromised Patients

Risk for Emergence of Dengue and Chikungunya Virus in Israel

We report the molecular evidence of dengue virus (DENV) and chikungunya virus (CHIKV) infection in symptomatic individuals in Cameroon and Gabon, respectively. Arthropod-borne viruses (arboviruses) are distributed in the tropical or subtropical regions, with DENV having the highest burden. The morbidity and mortality related to arboviral diseases raise the concern of timely and efficient surveillance and care. Our aim was to assess the circulation of arboviruses [DENV, CHIKV, Zika virus (ZIKV)] among febrile patients in Dschang (West Cameroon) and Kyé-ossi (South Cameroon, border with Gabon and Equatorial Guinea). Dried blood spots were collected from 601 consenting febrile patients, and 194 Plasmodium spp.-negative samples were tested for the molecular detection of cases of DENV, CHIKV and ZIKV infection. Overall, no case of ZIKV infection was found, whereas one case of DENV infection and one case of CHIKV infection were detected in Dschang and Kyé-ossi, respectively, with the CHIKV-infected patient being resident in Gabon. Our findings suggest the need to establish an active surveillance of arbovirus transmission in Cameroon and bordering countries.

Chikungunya virus (CHIKV) infection has been commonly detected in tropical countries. The clinical manifestations of CHIKV infection are similar to those of rheumatoid arthritis. Outbreaks of CHIKV infection in Thailand have been reported, and the inductions of various cytokines and chemokines in CHIKV patients during those outbreaks have been shown. Although immune responses in CHIKV infection have been increasingly reported, the mechanisms associated with pathology induction are still not clearly understood. This review focuses on cytokine and chemokine production in CHIKV infection, in association with the severity of joint inflammation. Several cytokines and chemokines involved in the induction or regulation of inflammatory responses were shown to associate with the severe and persistent symptoms in CHIKV infection. Further studies on the difference in immune responses observed in an autoimmune disease, rheumatoid arthritis, infectious disease, and CHIKV infection, would provide additional insights useful for proper CHIKV therapy, especially in patients with severe joint pains.

Being obligate parasites, viruses use various host cell machineries in effectively replicating their genome, along with virus-encoded enzymes. In order to carry out infection and pathogenesis, viruses are known to manipulate fundamental cellular processes in cells and interfere with host gene expression. Several viruses interact with the cellular proteins involved in the Wnt/β-catenin pathway; however, reports regarding the involvement of protein components of the Wnt/β-catenin pathway in Chikungunya virus (CHIKV) infection are scarce. Additionally, there are currently no remedies or vaccines available for CHIKV. This is the first study to report that modulation of the Wnt/β-catenin pathway is crucial for effective CHIKV infection. These investigations deepen the understanding of the underlying mechanisms of CHIKV infection and offer new avenue for developing effective countermeasures to efficiently manage CHIKV infection.

Yellow fever (YF), Chikungunya (CHIK), and Zika(ZIK) are among re-emerging arboviral diseases of major public health concern. Despite the proximity of the Gambella Region to South Sudan where arboviral cases have been recorded repeatedly the current epidemiological situation is unclear in this part of southwest Ethiopia. Therefore, we conducted a community-based seroprevalence survey of YF virus (YFV), CHIK virus (CHIKV), and ZIK virus (ZIKV) infections in two selected districts. A cross-sectional study was conducted in two locations of the Gambella region (Lare and Itang) to investigate the seroprevalence of these viruses’ infections. Blood samples were collected from the study participants and screened for IgG antibodies specific to YFV and CHIKV infections using enzyme-linked immunosorbent assays (ELISA). For the detection of ZIKV specific IgG antibodies, Blockade-of-binding ELISA was used. Data were analyzed using the STATA version 13.1 Softwares. A total of 150 individuals (96 males and 54 females, age ranging from 18 to 65 years, mean age ± SD = 35.92 ± 10.99) participated and provided blood samples. Among the 150 samples 135, 90, and 150 were screened for YFV, CHIKV, and ZIKV, respectively. Hence, 2.9% (95% CI: 1.1–7.7%), 15.6% (95% CI: 9.3–24.8%), and 27.3% (95% CI: 20.7–35.3%) of samples tested positive for IgG antibodies to YFV, CHIKV, and ZIKV infections, respectively. Among the individual seropositive for ZIKV, YFV and CHIKV, only six, one and three had a history of residence outside the Gambella region respectively. Agro-pastoral occupation was significantly associated with a higher prevalence of IgG against CHIKV (AOR = 14.17; 95%CI: 2.30, 87.30) and residency in the Lare district (AOR = 11; 95%CI: 3.31, 39.81) was found to be significantly associated with a higher prevalence of IgG against ZIKV. Our findings revealed the occurrence of YFV, CHIKV and ZIKV infections in the study locations.

Chikungunya virus (CHIKV), a re-emerging infectious arbovirus, causes Chikungunya fever that is characterized by fever, skin rash, joint pain, arthralgia and occasionally death. Despite it has been described for 66 years already, neither potential vaccine nor a specific drug is available yet. During CHIKV infection, interferon type I signaling pathway is stimulated and releases hundreds of interferon stimulated genes (ISGs). Our previous study reported that IFI16, a member of ISGs, is up-regulated during CHIKV virus infection and the suppression of the gene resulted in increased virus replication. Furthermore, our group also found that inflammasome activation can inhibit CHIKV infection in human foreskin cells (HFF1). Concomitantly, it has been reported that IFI16 activates the inflammasome to suppress virus infection. Therefore, we have hypothesized that IFI16 could be involved in CHIKV infection. In this study, we confirmed the expression level of IFI16 by Western blotting analysis and found that IFI16 was up-regulated following CHIKV infection in both HFF1 and human embryonic kidney cells. We next investigated its antiviral activity and found that forced expression of IFI16 completely restricted CHIKV infection while endogenous silencing of the gene markedly increased virus replication. Furthermore, we have discovered that IFI16 inhibited CHIKV replication, at least, in cell-to-cell transmission as well as the diffusion step. Interestingly, IFI16 also exerted its antiviral activity against Zika virus (ZIKV) infection, the global threat re-emerging virus can cause microcephaly in humans. Taken together, this study provides the first evidence of an antivirus activity of IFI16 during in vitro arbovirus infection, thus expanding its antiviral spectrum that paves the way to further development of antiviral drugs and vaccines.

We compared the morbidity and quality of life of military policemen ("gendarmes") infected with chikungunya virus (CHIKV+) 30 months after contamination. We categorized the subjects in 3 groups: healed patients (n = 48), non-healed patients (n = 37, 44% of CHIKV+), and uninfected subjects (CHIKV-, n = 297). Data were self-recorded in this retrospective cohort study; they included sociodemographic information, clinical symptoms, and the Medical Outcome Study 36-item short-form health survey (MOS-SF36) quality of life questionnaire. The study population was mostly men (92%), with a median age of 42.8 years, regardless of CHIKV status. The main complaints were rheumatic symptoms (pain, stiffness, and swelling), reported 5 times more often by non-healed CHIKV+ subjects and 2-3 times more often by healed CHIKV+ subjects than by CHIKV- subjects, and fatigue. The CHIKV+ patients reported more use of health care services. Thirty months after infection, all rheumatic symptoms were more frequent and intense among CHIKV+ than among CHIKV- subjects, with a gradient of severity between healed and non-healed CHIKV+ subjects. Non-healed CHIKV+ subjects reported subsequent limitation in their activities. All dimensions of MOS-SF36 as well as physical and mental component summaries were impaired in CHIKV+ compared to CHIKV- subjects, with a decreasing gradient of impairment from non-healed to healed CHIKV+ subjects, then to CHIKV- subjects. These observations confirm the long-term impact of CHIKV infection on both physical and mental health. Questions persist regarding the duration of this impairment and the possibility of a return to "before CHIKV" health status for infected patients.

Introduction: Dengue and Chikungunya have re-emerged as important diseases of global concern. Co-infections with Dengue virus (DENV) and Chikungunya virus (CHIKV) could have serious outcomes if not diagnosed and managed optimally. However, the key focal points for the maintenance of CHIKV and DENV infections and the extent of their co-infection remain poorly understood in many geo-ecologically distinct parts of Tanzania. Objective: We aimed to comparatively examine the prevalence and factors for seropositivity to DENV and CHIKV and their infection rates in humans and mosquitoes Methods: A cross-sectional study was performed in the Lower Moshi area of the Kilimanjaro region from April to July 2020. DENV and CHIKV exposure was determined by detecting IgM to the viruses using enzyme linked immunosorbent assay whereas infection was determined by real time quantitative polymerase chain reaction (RT-qPCR) assay. Results: Insecticide Treated Bed Net (ITN) use (χ2=3.504; p< 0.05), being ≥7 individuals living in the same household (χ2=4.655; p<0.05) and a recent travel to an urban destination (χ2=3.39; p< 0.05) were the only factors associated with CHIKV seropositivity. ITN use was the only factor associated with CHIKV infection (χ2=5.204; p<0.05). A recent travel to an urban destination (χ2=4.401; p< 0.05) was the only factor associated with DENV seropositivity. Five (1.5%) Ae. aegypti pools were positive for CHIKV whereas 1 (0.3%) was positive for DENV. Two Cx. pipiens, pools (1.9%) were positive for CHIKV. None of the Cx. pipiens mosquitoes was positive for DENV. No associations between DENV and CHIKV seropositivity was observed in humans but DENV infection was strongly associated with CHIKV infection (χ2 = 238.45; p<0.01). CHIKV infection was observed to be consistently higher in both, humans and mosquitoes. Conclusion: Detection of DENV and CHIKV in both humans and vector mosquitoes confirms that both viruses are actively circulating in the Lower Moshi area of Kilimanjaro region in Tanzania. Our findings point out the Lower Moshi area as a potential focal point for the maintenance of the two viruses and possibly other vector borne viruses. We call upon sustained active surveillance of arboviruses and other re-emerging infections to be better prepared for possible outbreaks by the viruses.

Limited information is available on the seroprevalence of chikungunya virus (CHIKV) infection and maternal-fetal transmission incidence of CHIKV and dengue virus (DENV) infections during the 2008-2009 CHIKV outbreak in southern Thailand. A community-based post-epidemic seroprevalence study was conducted in parturient women admitted to the Thepa District Hospital in Songkhla Province, Thailand, for delivery from November 2009 to May 2010. The women were tested for chikungunya (CHIK) IgM/IgG and dengue (DEN) IgM/IgG. Cord blood samples were also tested for CHIK IgM or DEN IgM in women who tested positive for CHIK IgM or DEN IgM, respectively. The seroprevalence of CHIKV infection (CHIK IgM or IgG positive) was 227/319 (71·2%) with pre-outbreak seroprevalence (IgM-/IgG+) of 43·6% and the seroprevalence of DENV infection was 288/319 (90·3%). Complications during pregnancy, newborn outcomes and congenital anomalies were not different in those who had recent, remote or no CHIKV infections. None of the newborns whose mothers were CHIK or DEN IgM positive had cord blood positive for both CHIK and DEN IgM. In conclusion, both CHIKV and DENV are endemic in southern Thailand; during the recent CHIKV outbreak CHIK seroprevalence increased from 43·6% to 71·2%.

Understanding the risk of chikungunya virus (CHIKV) infection and rheumatic sequelae across populations, including travelers and the military, is critical. We leveraged healthcare delivery data of over 9 million U.S. Military Health System (MHS) beneficiaries to identify cases, and sampled controls, to estimate the risk of post-CHIKV rheumatic sequelae. MHS beneficiary CHIKV infections diagnosed 2014-2018 were identified from the Disease Reporting System internet, TRICARE Encounter Data Non-Institutional, and Comprehensive Ambulatory/Professional Encounter Record systems. Non-CHIKV controls were matched (1:4) by age, gender, beneficiary status, and encounter date. The frequency of comorbidities and incident rheumatic diagnoses through December 2018 were derived from International Classification of Diseases codes and compared between cases and controls. Poisson regression models estimated the association of CHIKV infection with rheumatic sequelae. We further performed a nested case-control study to estimate risk factors for post-CHIKV sequelae in those with prior CHIKV. 195 CHIKV cases were diagnosed between July 2014 and December 2018. The median age was 42 years, and 43.6% were active duty. 63/195 (32.3%) of CHIKV cases had an incident rheumatic diagnosis, including arthralgia, polyarthritis, polymyalgia rheumatica, and/or rheumatoid arthritis, compared to 156/780 (20.0%) of controls (p < 0.001). CHIKV infection remained associated with rheumatic sequelae (aRR = 1.579, p = 0.008) after adjusting for prior rheumatic disease and demography. Those with rheumatic CHIKV sequelae had a median 7 healthcare encounters (IQR 3-15). Among CHIKV infections, we found no association between post-CHIKV rheumatic sequelae and demography, service characteristics, or comorbidities. CHIKV infection is uncommon but associated with rheumatic sequelae among MHS beneficiaries, with substantial healthcare requirements in a proportion of cases with such sequelae. No demographic, clinical, or occupational variables were associated with post-CHIKV rheumatic sequelae, suggesting that prediction of these complications is challenging in MHS beneficiaries. These findings are important context for future CHIKV vaccine decision making in this and other populations.

Establishment of a viral infection in the host involves complex interactions between the virus and the host. The present study was undertaken to evaluate one such interaction between a host microRNA (miRNA) with both the virus and its cellular target. Through a comprehensive high-throughput screen of a human miRNA mimics library, we identified that hsa-miR-122b-5p bound to chikungunya virus (CHIKV) 3'-untranslated region (3'-UTR), which we abrogated upon mutating the binding sites of the miRNA and determined that this miRNA regulated CHIKV infection. In-depth scrutiny of this miRNA's expression in CHIKV-susceptible host cells divulged that it was mainly expressed in macrophages, and temporal expression profiling analysis in these cells revealed that its expression negatively correlated to the virus infection. We further identified cellular targets of miR-122b-5p through global RNA seq analysis using antagomiRs, among which histone deacetylase 4 (HDAC4) displayed attributes that promoted CHIKV infection in macrophages. To dissect this phenomenon further, we performed loss-of-function assays using both miR-122b-5p and HDAC4 and observed regulation of pro-inflammatory cytokines, including the type I interferon system. Furthermore, miRNA mimics and antagomiR assays indicated that regulation of HDAC4 by miR-122b-5p may be associated with changes in the nuclear translocation of phosphorylated IRF3 during CHIKV infection. While this suggests a possible link, additional studies are needed to confirm this interaction and its underlying mechanism. Taken altogether, our study provides insights into the dual regulatory function of miR-122b-5p during CHIKV infection, highlighting its capacity to decrease viral titer by binding directly to the 3'UTR of the viral genome and its potential to promote nuclear translocation of phosphorylated IRF3, which may be indirectly influenced by modulation of its cellular target, HDAC4, thereby regulating host immune responses during CHIKV infection in macrophages. These findings may have significant implications for understanding the pathogenesis of CHIKV and for developing novel therapeutic strategies.IMPORTANCEHuman microRNAs (miRNAs) are central regulators of viral infection, acting through direct targeting of viral genomes or by modulating host cellular pathways. In this study, we demonstrate that miR-122b-5p plays a dual antiviral role during chikungunya virus (CHIKV) infection in macrophages-critical immune cells that serve as viral reservoirs. We show that miR-122b-5p directly binds to the 3' untranslated region of the CHIKV genome, thereby suppressing viral replication. Additionally, we uncover a previously uncharacterized mechanism in which miR-122b-5p modulates the host innate immune response by repressing HDAC4, a negative regulator of the type I interferon pathway. This repression may influence nuclear translocation of phosphorylated IRF3, potentially enhancing the antiviral transcriptional response. Our findings not only deepen our understanding of macrophage-intrinsic antiviral defenses against CHIKV but also highlight miR-122b-5p as a potential therapeutic target for enhancing host immunity and limiting viral propagation.

Chikungunya virus (CHIKV) infection is endemic in many different countries. CHIKV outbreaks are emerging in new areas and re-emerging in previously exposed geographical regions, thus making it a significant public health concern. CHIKV infections are often clinically inapparent, especially in children, which poses a challenge to testing and evaluating any vaccine. During CHIKV infection, CHIKV-specific antibodies are produced, and some of these antibodies can neutralize viruses released from infected cells before they can enter uninfected cells. In this study, we evaluated IgG binding and neutralizing antibody responses in paired serum samples from CHIKV-infected children and those with other febrile illness, using a recombinant truncated E2 protein and whole CHIKV particles as test antigens. Antibody detection using the truncated E2 protein showed a significant overlap between CHIKV-infected subjects and those with other febrile illnesses. This overlap was greater when binding antibody titers were determined using fixed CHIKV particles as the test antigen. Acute- and convalescent-phase sera collected from children after CHIKV infection showed significant differences in their neutralizing capacity. The neutralizing and binding antibody response showed a significant positive correlation. We detected IgG antibodies in most cases during the acute phase of infection. This was observed at two different geographical locations, one of which is not considered highly endemic. Conventional wisdom would suggest this to be a marker of re-infection (secondary infection). However, dissenting opinions have been voiced in other viral diseases (such as Ebola) where studies have detected IgG in acute illness. In the absence of any significant body of work documenting secondary CHIKV infections, we believe further work is needed to understand the early IgG response that we observed.

Chikungunya is a febrile infection caused by the Chikungunya virus (CHIKV), an alphavirus which has emerged as a serious public health problem globally. Despite extensive research, our understanding of different host factors facilitating effective CHIKV infection is not clear yet. NEDD4, a member of the E3 ubiquitin ligase, is one such protein. Here, the importance of NEDD4 has been explored during CHIKV infection in vitro. It was observed that the level of NEDD4 is downregulated after CHIKV infection. Interestingly, the CHIKV-nsP3 level and the viral load were decreased significantly when NEDD4 was silenced, while a 93% decrease in the viral load was observed in the case of NEDD4 overexpression, indicating the importance of an optimum level of NEDD4 for effective CHIKV infection. Further study revealed that there was interaction between the NEDD4 and CHIKV-nsP3 proteins through co-immunoprecipitation (CO-IP) during CHIKV infection. Additionally, in silico data illustrated that the WW domain of NEDD4 can bind to the nsP3, as well as the macrodomain of nsP3 (nsp3-MD) of CHIKV. These data were further confirmed by the pull-down assay with purified nsP3-MD. The finding suggested that the host protein NEDD4 might interact directly with nsP3-MD during the CHIKV infection. However, the presence of a faint band of NEDD4 along with nsP3-MD in the pull-down assay may indicate the involvement of some other residues for this interaction. These in silico data were further confirmed by the CO-IP experiments, where all domains of nsP3, MD (macrodomain), AUD (alphavirus unique domain) and HVD (hypervariable domain) were found to interact with NEDD4. Additional experiments with a truncated form of MD, MD1 (1–100 residues of amino acid), revealed that this region is not able to maintain the interaction with NEDD4, indicating the crucial role of the C-terminal region of MD for this binding. In conclusion, these findings offer valuable insights about the importance of NEDD4 during CHIKV infection and the residues of nsP3 for its interaction, which might be useful to design future therapeutics against CHIKV.

To the Editor: Chikungunya virus (CHIKV) infection is a self-limiting illness characterized by fever, headache, weakness, rash, and arthralgia. Some patients have prolonged weakness or arthralgia lasting several months. In 2006, several Indian Ocean states and India had an outbreak of CHIKV infection (1,2). During the epidemic’s peak, some European and American travelers returning from these areas were infected (3–6). Because the foci of Aedes albopictus, 1 of the 2 main vectors of CHIKV, are now in Italy and many travelers visit CHIKV-epidemic areas, surveillance for imported cases is mandatory in Italy (7). From July to September 2006, a total of 17 confirmed cases of CHIKV infection were observed in travelers at 5 Gruppo di Interesse e Studio delle Patologie di Importazione (GISPI) centers (Italian network of Institutes of Infectious and Tropical Diseases). Serologic diagnosis was performed with a hemagglutination-inhibition test and confirmed by a plaque-reduction neutralization test (8). Demographic and epidemiologic characteristics of these patients are reported in the Table. Table Demographic and epidemiologic data on 17 travelers with chikungunya infection diagnosed in 2006, Italy Cases were distributed throughout the year with a peak from March to May 2006 (n = 10). Nine patients (53%) were men. Median age was 43 years (range 31–66 years). Several reasons for travel were reported: tourism (64.6%), visits to relatives or friends (11.8%), business (11.8%), and missionary work (5.9%). One patient was a resident in the disease-epidemic area. The median exposure time in the CHIKV-endemic area for the 15 travelers was 15 days (range 9–93 days) (missionary and resident patients were excluded). The median delay before being seen at a clinic after return was 2 days (range 0–73 days). Only 7 patients (41.2%) were hospitalized. The remainder were outpatients. All patients had fever; arthralgia (88.2%, n = 15), weakness (70.6%, n = 12), headache (11.8%, n = 2), diarrhea (11.8%, n = 2), and gum bleeding and epistaxis (5.9%, n = 1) were other reported symptoms. The median duration of fever was 5 days (range 2–12 days). Only 7 of 16 patients (43.8%) were still febrile when first seen. Physical examination showed diffuse macular erythematous rash in 13 patients (76.5%), a similar rate to that reported among French travelers (4). Hepatomegaly was found in 2 patients (11.8%), splenomegaly in 2 (11.8%), and peripheral lymphadenopathy in 2 (11.8%). Twelve acute-phase patients were admitted to the hospital for blood testing within 3 days of the initial examination. In contrast with results of other studies, leukopenia and thrombocytopenia were uncommon in our study. Leukopenia (leukocyte count 40 IU/L) in 5 (41.7%) and 2 (16.7%) patients, respectively. Seven (46.7%) of 15 patients fully recovered within 1 month; 8 patients (53.3%) reported persistent arthralgia. Because the GISPI network provides regional coverage only, the number of imported CHIKV cases in all of Italy in 2006 was likely higher. Moreover, most patients probably did not seek medical care, and when they did, physicians may have failed to recognize the disease because of lack of familiarity with it or limited diagnostic facilities. Differential diagnosis with other arthropodborne viruses of the Alphavirus genus (Ross River, Barmah Forest, o’nyong nyong, Sindbis, and Mayaro viruses) is difficult, but these are comparatively rare. In contrast, dengue and CHIKV epidemics may overlap, and potential patients should be screened for both. The potential risk for introduction and establishment of CHIKV reservoirs in areas with mosquito vectors was discussed in March 2006 by a multidisciplinary European expert panel (9). In Italy, A. albopictus was first recorded in 1990; it has since quickly spread across the country. Scattered foci are now reported in almost all regions, mainly along the coastal plains, from the sea to the inlands, up to an altitude of ≈500–600 m (7). The ability of A. albopictus to colonize new areas and its adaptability to the mild Italian climate allow vector populations to be active throughout the year (10). The patient is thought to be viremic for only 6–7 days (shortly before and during the febrile period) (6). We were unable to directly assess viremia levels; however, almost half the patients were still febrile on return to Italy, which suggests a potential risk. Although the same mosquito is a potential vector of dengue, no autochthonous case has been reported as yet, despite annual reports of many imported dengue cases in Italy. On the other hand, the clinical manifestations of both conditions are nonspecific, and a hypothetical autochthonous case would most likely go undiagnosed unless a targeted surveillance system were established. Prompt reporting of imported CHIKV infections is essential for monitoring of potential risk. The possibility of introducing CHIKV into Italy cannot be ruled out on the basis of current evidence.

Chikungunya virus imported into French Polynesia, 2014.