Th2-predominant immune response underlies the pathogenesis of Dengue.

BACKGROUND: Dengue is a rapidly emerging pandemic-prone disease, whose manifestations range from asymptomatic infection to life-threatening complications like Dengue Hemorrhagic Fever and Dengue Shock Syndrome. This study investigates and compares the immune response in clinically defined cohorts of Dengue with and without warning signs, with the aim of identifying immunological correlates of clinical disease and potential markers of disease severity. METHODS: Blood samples, collected from study participants fulfilling the WHO definition of Dengue with and without warning signs and healthy volunteers, were analyzed using flow cell-based fluorometric methods for cytokines and chemokines. Gene expression analysis, using RT-PCR, was conducted on T helper cell subset-specific transcription factors and cytokines. Demographic details, virological markers, serotype distribution, and hematological parameters were also investigated in all the subjects. RESULTS: The 35 participants recruited in the study, included 11 healthy volunteers and 12 patients each fulfilling the WHO criteria of Dengue with and without warning signs. While the demographic characteristics and serotype distribution was similar in Dengue with and without warning signs cohorts of the disease, platelet counts and Aspartate Aminotransferase (AST) levels changed significantly between Dengue with and without warning signs patients. Plasma cytokine analysis showed up-regulation of IL-4, IL-10, IP-10, and MCP-1 in Dengue patients compared to healthy volunteers. Disease severity was associated with elevated levels of IL-10, IP-10, IL-4, MCP-1, and MIP-1α. IL-8 and MIP-1α were significantly up-regulated in Dengue with warning sign compared to Dengue without warning signs cases. Transcription factor analysis indicated increased expression of RORα, FoxP3, and GATA3 in Dengue patients. mRNA expression of TGFß and IL-4 was also elevated in Dengue patients. A positive correlation between mRNA expression of IL-4 and plasma IL-4 was observed. CONCLUSION: The study reveals a Th2-predominant immune response in all Dengue patients, regardless of disease severity, with overexpression of IL-8 and MIP-1α being observed in patients with warning signs.

Mannitol Is Comparable to Hypertonic Saline for Raised Intracranial Pressure in Acute Liver Failure (MAHAL Study): A Randomized Controlled Trial.

BACKGROUND: Raised intracranial pressure (ICP) due to cerebral edema (CE) is central to development of hepatic encephalopathy in acute liver failure (ALF). Mannitol (MT) and hypertonic saline (HS) have been shown to improve CE. We compared the efficacy and safety of the 2 modalities. METHODS: ALF with CE was prospectively randomized in an open study to receive either 5 mL/kg of either 3% HS, as continuous infusion; titrated every 6 hourly to achieve serum sodium of <160 (Group A; n = 26) or 1 g/kg of 20% MN as a IV bolus, repeated every 6 hourly (Group B; n = 25) in addition to standard ALF care. Primary end-point was reduction of ICP defined as optic nerve sheath diameter <5 mm and middle cerebral arterial pulsatility index <1.2 at 12 h. RESULTS: Fifty-one patients with ALF, hepatitis E being commonest (33.3%), median jaundice to HE interval of 8 (1-16) days, were randomized to HS (n = 26) or MN (n = 25). Baseline characteristics were comparable including King's college criteria (>2: 38.4% vs.40%). Overall, 61.5% patients in the HS and 56% in the MN group showed reduction in ICP at 12 h (p = 0.25). Rebound increase in ICP indices was noted in 5 (20%) patients in MT and none in HS (p < 0.05) group. New onset acute kidney injury was common in the MT group than in the HS group. The ICU stay and 28-day transplant-free survival were not different between the groups. CONCLUSIONS: While both agents had comparable efficacy in reducing ICP and mortality in ALF patients was comparable, HS was significantly better in preventing reducing rebound CE with lower renal dysfunction.

Humoral Immune Responses and Hepatitis B Infection.

BACKGROUND: Chronicity or seroclearance of hepatitis B virus (HBV) antigens is determined by the host immune responses. Current approaches to treat HBV patients are based on inhibition of replication using different antivirals (nucleoside or nucleotide analogs) as monotherapy, or along with immune modulators as combination therapy is being used worldwide for reducing the viral load. Understanding the role of immune cellular therapies with currently available treatments for persistent viral-mediated responses in HBV patients is unexplored. However, the generation of antibodies against a surface (HBs) and envelop (HBe) antigen of hepatitis B remains an issue for future studies and needs to be explored. SUMMARY: Humoral immunity, specifically T follicular helper (TFh) cells, may serve as a target for therapy for HBsAg seroconversion. In this review, we have been engrossed in the importance and role of the humoral immune responses in CHBV infection and vertical transmission. Key Message: TFh cells have been suggested as the potential target of immunotherapy which lead to seroconversion of HBe and HBs antigens of HBV. HBsAg seroconversion and eradication of covalently closed circular DNA are the main challenges for existing and forthcoming therapies in HBV infection.

Omega-3 fatty acid lipid emulsions are safe and effective in reducing endotoxemia and sepsis in acute-on-chronic liver failure: An open-label randomized controlled trial.

BACKGROUND AND AIM: Sepsis is an important determinant of the outcome of acute-on-chronic liver failure (ACLF) patients. Omega-3 fatty acids (FAs) are known to suppress inflammation, reduce morbidity, and mortality in postoperative and critically ill patients. We aimed to evaluate the effect of intravenous omega-6 and omega-3 FA lipid emulsions in ACLF patients. METHODS: Ninety ACLF patients were randomly allocated to three groups: Gr. A received no lipid emulsions, Gr. B received omega-6 FAs, and Gr. C received omega-3 FAs. The primary and secondary aims were to compare the effects of lipid emulsions on immune modulation, the incidence of bacterial sepsis, and mortality at day 28. RESULTS: The baseline characteristics of the patients were comparable. Serum endotoxin levels remained suppressed by 22% in Gr. C compared with a 4% and 12% rise in Gr. B and A (P < 0.001). Omega-3 FAs also suppressed C-reactive protein levels and neutrophil-to-lymphocyte ratio in Gr. C. Compared with Gr. A, omega-3 FAs reduced sepsis by 86% (HR, 0.14; 95% CI 0.04-0.43; P < 0.001). Omega-3 FAs significantly increased the expression of TLR2 and TLR4 on both CD14+ and CD16+ monocytes, and TLR4, on macrophages and neutrophils. There were no serious adverse events, except transient flushing in 20% and 16.6% of patients receiving omega-6 FAs and omega-3 FAs, respectively. CONCLUSION: Omega-3 FAs are safe and effective in reducing systemic inflammation, endotoxemia, and sepsis in patients with ACLF. These lipid emulsions could also be considered as effective sources of immunonutrition in such sick patients.

Dichotomy of Notch signalling in regulating tumour immune surveillance.

Notch signalling is an evolutionarily conserved multifaceted pathway that controls diverse cellular processes. Its role in regulating development and tissue homeostasis is well established. Aberrant activation of the Notch pathway has been implicated in the initiation and progression of many types of cancers. However, although in some cancers Notch signalling acts as a tumour-promoter, in others it is reported to suppress tumour growth and progression. Accumulating evidence suggests the involvement of both the innate and adaptive immune system in the development of various tumours. Currently, extensive studies on investigating the effects of Notch signalling in tumour immune surveillance are being carried out. Interestingly, recent literature shows how the changing expression of Notch genes in different T cell subsets like CD4 and CD8 helps in controlling anti-tumour immune responses. In this review, we discuss in depth the roles of Notch signalling molecules and different immune cells in the context of the tumour microenvironment. We also outline how current knowledge can be exploited to develop novel therapies in order to control the propagation of cancer stem cells.

Immune correlates of hepatitis B surface antigen spontaneous seroconversion in hepatitis B e antigen negative chronic hepatitis B patients.

BACKGROUND: Hepatitis B surface antigen (HBsAg) seroconversion in HBeAg -ve chronic hepatitis B (CHB) infection is rare, possibly due to poor antigen processing and impaired humoral response. We investigated the role of dendritic cells (DCs), T follicular helper (TFH) cells and plasma B cells in seroconversion. METHODS: HBeAg -ve (n=135) CHB patients with raised ALT at baseline were followed up. Patients undergoing HBsAg seroconversion (Gr. I, n=11) were compared with non-converters with low (Gr. II, n=17, HBV DNA<2000 IU/mL) or high HBV DNA (Gr. III, HBV DNA >2000 IU/mL, n=17). We measured cell phenotypes (TFH, B and DCs), HBV specific T-cell functionality [using pooled overlapping surface and core peptides], IL21 levels and gene expression analysis by qRT-PCR. RESULTS: Patients in Gr. I compared to Gr. II and III, had higher IL-21 levels (865 vs 276 vs 111 pg/mL, P=<.0001), TFH (CD4+ CXCR5+ ) cells (12.3 vs 4.67 vs 2.77, P=<.001), inducible T-cell co-stimulator (ICOS) expression on TFH cells (20.0 vs 13.0 vs 13.68, P=.01), HBsAg specific IL-17 (9.40 vs 2.33 vs 2.61, P=<.001) and TNF-α secreting TFH17 cells (82 vs 1.43 vs 2.33, P=<.001), plasma B (CD19+ CD38+ ) cells (15.0 vs 5.08 vs 5.57, P=<.001), myeloid (17.80 vs 5.39 vs 2.70, P=<.001) and plasmocytoid DCs (2.6 vs 0.43 vs 0.21, P=<.001). Plasma B-cell frequency (R2 =.64, P=.01) and IL-21 levels (R2 =.52, P=.003) correlated with anti-HBs titres in patients with HBsAg seroconversion. CONCLUSIONS: Dendritic cell and TFH cell mediated responses regulate humoral responses against HBV and play a major role in HBsAg seroconversion in CHB patients.

Placental expression of asialoglycoprotein receptor associated with Hepatitis B virus transmission from mother to child.

BACKGROUND: Asialoglycoprotein receptor expression on hepatocytes has been associated with endocytosis, binding and uptake of hepatitis B virus. The role of asialoglycoprotein receptor in hepatitis B virus vertical transmission and its expression on placenta has not yet been studied. PATIENTS AND METHODS: Thirty-four HBsAg+ve and 13 healthy pregnant mothers along with their newborns were enrolled. The former were categorized into transmitting and non-transmitting mothers based on their newborns being hepatitis B surface antigen and hepatitis B virus DNA positive. Expression of asialoglycoprotein receptor and hepatitis B surface antigen in placenta and isoform of asialoglycoprotein receptor on dendritic cell in peripheral and cord blood dendritic cells were analysed using flowcytometry, immune histochemistry, immune florescence and qRT-PCR. RESULTS: Twelve HBsAg+ve mothers transmitted hepatitis B virus to their newborns whereas the rest (n = 22) did not. Hepatitis B virus-transmitting mothers showed increased expression of asialoglycoprotein receptor in trophoblasts of placenta. Immunofluorescence microscopy revealed colocalization of hepatitis B surface antigen and asialoglycoprotein receptor in placenta as well as in DCs of transmitting mothers. There was no significant difference in the expression of asialoglycoprotein receptor on peripheral blood mononuclear cells or chord blood mononuclear cells between the 2 groups. However, hepatitis B virus-transmitting mothers and their HBsAg+ve newborns showed increased mRNA levels of isoform of asialoglycoprotein receptor on dendritic cell in peripheral blood mononuclear cells. Hepatitis B virus-transmitting mothers and their HBsAg+ve newborns showed an increased expression of isoform of asialoglycoprotein receptor on dendritic cell on circulating dendritic cells compared to hepatitis B virus non-transmitting mothers and their negative newborns. CONCLUSIONS: This study revealed that increased expression of asialoglycoprotein receptor in placenta and colocalization with hepatitis B surface antigen strongly indicates its role in intrauterine transmission of hepatitis B virus. Asialoglycoprotein receptor-blocking strategy can be used for therapeutic intervention of vertical transmission.

Higher efficacy of pegylated interferon-α2b add-on therapy in hepatitis B envelope antigen-positive chronic hepatitis B patients on tenofovir monotherapy.

AIM: Monotherapy with pegylated interferon-α (Peg-IFNα) or the nucleos(t)ide analogs (NA) currently approved for treating chronic hepatitis B (CHB) has limited efficacy. Studies on the combination of Peg-IFNα/NA have shown conflicting results. We investigated whether sequentially adding on Peg-IFNα to tenofovir enhances serological response rates. METHODS: Treatment-naïve, hepatitis B envelope antigen (HBeAg)-positive CHB patients with moderately elevated alanine aminotransferase (ALT; 48-200 IU/mL) were started on tenofovir (300 mg/day) and enrolled at week 12 in a 1:1 ratio to either receive Peg-IFNα2b add-on (1.5 µg/kg/week) from week 12 to 36 (n = 53) or continue tenofovir monotherapy (n = 53). Both treatment arms received tenofovir consolidation therapy until week 72. The primary end-point was HBeAg loss at week 72. RESULTS: At week 72, the rate of HBeAg loss was higher in the Peg-IFNα2b add-on group (35.8%) compared to the tenofovir monotherapy group (17%) (P = 0.028; odds ratio, 2.73, 95% confidence interval, 1.09-6.79), and considerably higher in patients with a baseline hepatitis B virus (HBV)-DNA level >6 log IU/mL (32.6% vs 11.4%; P = 0.021). Rates of HBV-DNA loss (77.4% vs 71.7%; P = 0.51), ALT normalization (62.3% vs 52.8%; P = 0.32), and sustained virologic response (20.8% vs 11.3%; P = 0.18) at week 72 were comparable between the two groups. Significantly more patients in the add-on group had >3 log HBV-DNA reduction at week 36 (92.5% vs 66%; P = 0.001). Four patients treated with Peg-IFNα2b add-on achieved hepatitis B surface antigen (HBsAg) loss compared with one patient receiving tenofovir monotherapy. Decline of HBV-DNA of >2 log at week 4 led to higher HBeAg loss at week 72, independent of treatment arm. No patient had treatment-related adverse effects requiring treatment discontinuation. CONCLUSIONS: Twenty-four weeks of Peg-IFNα2b as an add-on sequential regimen to tenofovir is safe and resulted in greater loss of HBeAg and HBsAg compared to tenofovir monotherapy in selected HBeAg-positive patients. Viral load reduction followed by immune modulation is a potentially useful approach.

Combination of granulocyte colony-stimulating factor and erythropoietin improves outcomes of patients with decompensated cirrhosis.

BACKGROUND & AIMS: Patients with decompensated cirrhosis have significantly reduced survival without liver transplantation. Granulocyte colony-stimulating factor (G-CSF) has been shown to increase survival in patients with acute-on-chronic liver failure, and erythropoietin promoted hepatic regeneration in animal studies. We performed a double-blind, randomized, placebo-controlled trial to determine whether co-administration of these growth factors improved outcomes for patients with advanced cirrhosis. METHODS: In a prospective study, consecutive patients with decompensated cirrhosis seen at the Institute of Liver and Biliary Sciences, New Delhi (from May 2011 through June 2012) were randomly assigned to groups given subcutaneous G-CSF (5 µg/kg/d) for 5 days and then every third day (12 total doses), along with subcutaneous darbopoietin α(40 mcg/wk) for 4 weeks (GDP group, n = 29), or only placebos (control group, n = 26). All patients also received standard medical therapy and were followed for 12 months. Histology was performed on liver biopsies. The primary end point was survival at 12 months. RESULTS: Baseline characteristics of patients were comparable; alcohol intake was the most common etiology of cirrhosis. A higher proportion of patients in the GDP group than controls survived until 12 months (68.6% vs 26.9%; P = .003). At 12 months, Child-Turcotte Pugh scores were reduced by 48.6% in the GDP group and 39.1% in the control group, from baseline (P = .001); Model for End Stage Liver Disease scores were reduced by 40.4% and 33%, respectively (P = .03). The need for large-volume paracentesis was significantly reduced in GDP group, compared with controls (P < .05). A lower proportion of patients in the GDP group developed septic shock (6.9%) during follow-up compared with controls (38.5%; P = .005). No major adverse events were observed in either group. CONCLUSIONS: In a single-center randomized trial, a significantly larger proportion of patients with decompensated cirrhosis given a combination of G-CSF and darbopoietin α survived for 12 months more than patients given only placebo. The combination therapy also reduced liver severity scores and sepsis to a greater extent than placebo. Clinicaltrials.gov ID: NCT01384565.

Modulation of CD8+T cells, NK cells and Th1cytokines by metabolic milieu in decline of HBV-viremia in pregnant women treated with tenofovir-disoproxil from second trimester of pregnancy.

High HBV DNA levels predispose to mother to child transmission (MTCT) of HBV. Early nucleotide analogue (NA) therapy can reduce HBV DNA and minimize MTCT. We analysed immune-metabolic profile in pregnant mothers who received NA from 2nd trimester compared with untreated mothers. In 2nd trimester, there was no difference in immune profiles between Gr.1 and Gr.2 but high viral load women had downregulated pyruvate, NAD+ metabolism but in 3rd trimester, Gr.1 had significant reduction in HBV-DNA, upregulated pyruvate and NAD with increased IFN-2αA, CD8Tcells, NK cells and decreased Tregs, IL15, IL18, IL29, TGFß3 compared to Gr.2. In Gr.1, three eAg-ve women showed undetectable DNA and HBsAg. At delivery, Gr.1 showed no MTCT, with undetectable HBV DNA, HBsAg, high CD8 and NK cells in two women. We conclude, that starting NA from second trimester, reduces HBV load and MTCT, modulates NAD, induces immunity and suggest use of NA in early gestation in future trials.

Immune predictors of hepatitis B surface antigen seroconversion in patients with hepatitis B reactivation.

BACKGROUND: Hepatitis B surface antigen (HBsAg) seroconversion is sometimes observed in hepatitis B reactivation (rHBV), probably due to immune resetting and differentiation. AIMS: To investigate sequential immune differentiation and abrogation of tolerance in patients with rHBV who achieved HBsAg seroconversion. METHODS: We included 19 patients with chronic hepatitis B (CHBV; HBV DNA log103-8 ), 67 with rHBV (raised ALT [>5XULN], HBV DNAlog104-8 ) and 10 healthy controls. Immune differentiation, tolerance and functional status of CD4, CD8, T regulatory cells (Tregs), B cells and follicular T helper (Tfh) cells were assessed at baseline and 24 weeks. RESULTS: At 24 weeks, 81% rHBV (n = 67) lost HBV DNA and HBeAg (41%), and 12 (19%) lost HBsAg and made anti-HBs titers >10 IU/ml. rHBV patients had higher Th1/17, TEM , Tfh, Tfh1/17, plasma and ATM B cells, and lower Tregs, Th2, Th17 and TEMRA expression. rHBV showed lower PD1, TIM3, LAG3, SLAM and TOX compared to CHBV. There was a significant increase in CD8, CD8EM, Tfh, Tfh1/17 and plasma B cells in seroconverters than non-seroconverters. At 24 weeks, we also observed increased plasma B cell frequency in seroconverters. While non-seroconverters showed higher expression of PD1, TIM3, LAG3, SLAM and TOX on CD4/CD8 T cells, blockade of PD1, TIM3, LAG3 and CTLA4 significantly enhanced IFN-γ, TNF-α, IL-4 and IL-21 expression on CD4/CD8 and Tfh cells in non-seroconverters. CONCLUSIONS: Non-seroconverters have increased inhibitory markers on CD4/CD8 T cells. There is a critical play of CD8, Tfh and B cells and subsets in seroclearance, along with checkpoint molecules as a potential therapy for non-seroconverters in HBV infection.

Role of Streptococcus pneumoniae extracellular glycosidases in immune evasion.

Streptococcus pneumoniae (pneumococcus) typically colonizes the human upper airway asymptomatically but upon reaching other sites of the host body can cause an array of diseases such as pneumonia, bacteremia, otitis media, and meningitis. Be it colonization or progression to disease state, pneumococcus faces multiple challenges posed by host immunity ranging from complement mediated killing to inflammation driven recruitment of bactericidal cells for the containment of the pathogen. Pneumococcus has evolved several mechanisms to evade the host inflicted immune attack. The major pneumococcal virulence factor, the polysaccharide capsule helps protect the bacteria from complement mediated opsonophagocytic killing. Another important group of pneumococcal proteins which help bacteria to establish and thrive in the host environment is surface associated glycosidases. These enzymes can hydrolyze host glycans on glycoproteins, glycolipids, and glycosaminoglycans and consequently help bacteria acquire carbohydrates for growth. Many of these glycosidases directly or indirectly facilitate bacterial adherence and are known to modulate the function of host defense/immune proteins likely by removing glycans and thereby affecting their stability and/or function. Furthermore, these enzymes are known to contribute the formation of biofilms, the bacterial communities inherently resilient to antimicrobials and host immune attack. In this review, we summarize the role of these enzymes in host immune evasion.

Presence of entry receptors and viral markers suggest a low level of placental replication of hepatitis B virus in a proportion of pregnant women infected with chronic hepatitis B.

The transplacental route of vertical transmission of Hepatitis B Virus (HBV) has been known for over a decade. Here we present evidence which suggest HBV can replicate in placenta. Forty-one HBsAg positive and 10 control pregnant women were enrolled in the study after obtaining informed consent. HBV positives were further divided in the High Viral Load (HVL) Group and Low Viral Load (LVL) Group according to INASL guidelines 2018. The Presence of the HBV DNA and expression of NTCP in the placenta was analyzed by qPCR/RT-qPCR and/or immunohistochemistry (IHC). The presence of cccDNA was assessed using Digital Droplet PCR while the presence of pre-genomic (pg) RNA was assessed through qRT-PCR and sequencing. The presence of HBeAg and HBcAg in the placenta was assessed by IHC. Immunostaining of NTCP, HBeAg and HBcAg on trophoblasts along with the presence of total HBV DNA, cccDNA and pgRNA indicated, that these cells are not only susceptible to HBV infection but may also support viral replication. This is further supported by the finding that trophoblasts of the several HBeAg seronegative samples harbored the HBeAg. Although, we did not find any correlation in NTCP expression and viral markers with viral load indicates placental replication may not aping hepatocytes. The presence of the HBV receptor, NTCP along with the presence of cccDNA, pgRNA, and HBeAg in placenta of HBV infected females without circulating HBeAg suggest that placenta act as a replication host.

The role and delicate balance of Host Immunity in Coronavirus Disease-19.

Severe Acute Respiratory Syndrome (SARS) associated with SARS-CoV-2, causes a severe form of the respiratory illness known as Coronavirus Disease-19 (COVID-19). COVID-19 has emerged as a worldwide pandemic with a high number of fatalities. Approximately 112,654,202 people have been infected so far with this disease which has led to the death of more than one point seven million (2,496,749) till 24th Feb, 2021. Measures to counter this disease have led to a global economic slowdown. Multiple drug trials are ongoing and several putative candidates for vaccination against the virus have been approved and are in the pipeline. Many studies have also characterized the immunological profile of patients infected with COVID-19. Some studies suggest that the severity of the COVID-19 infection is directly associated with the cytokine storm. In this review, we aim to compile the available knowledge and describe the nature of immune responses in patients infected with COVID-19 in different age groups, comorbidity, and immune-compromised state and their association with disease severity.

Gut Dysbiosis and IL-21 Response in Patients with Severe COVID-19.

BACKGROUND: The disease severity, ranging from being asymptomatic to having acute illness, and associated inflammatory responses has suggested that alterations in the gut microbiota may play a crucial role in the development of chronic disorders due to COVID-19 infection. This study describes gut microbiota dysbiosis in COVID-19 patients and its implications relating to the disease. DESIGN: A cross sectional prospective study was performed on thirty RT-PCR-confirmed COVID-19 patients admitted to the All India Institute of Medical Sciences, Bhopal, India, between September 10 and 20, 2020. Ten healthy volunteers were recruited as the control group. IFN, TNF, and IL-21 profiling was conducted using plasma samples, and gut bacterial analysis was performed after obtaining the metagenomics data of stool samples. RESULTS: Patients with a variable COVID-19 severity showed distinct gut microflora and peripheral interleukin-21 levels. A low Firmicute/Bacteroidetes ratio, caused by the depletion of the fibre-utilizing bacteria, F. prausnitzii, B. Plebius, and Prevotella, and an increase in Bacteroidetes has associated gut microbiota dysbiosis with COVID-19 disease severity. CONCLUSIONS: The loss of the functional attributes of signature commensals in the gut, due to dysbiosis, is a predisposing factor of COVID-19 pathophysiology.

Laboratory diagnosis of COVID-19: current status and challenges.

The magnitude and pace of global affliction caused by Coronavirus Disease-19 (COVID-19) is unprecedented in the recent past. From starting in a busy seafood market in the Chinese city of Wuhan, the virus has spread across the globe in less than a year, infecting over 76 million people and causing death of close to 1.7 million individuals worldwide. As no specific antiviral treatment is currently available, the major strategy in containing the pandemic is focused on early diagnosis and prompt isolation of the infected individuals. Several diagnostic modalities have emerged within a relatively short period, which can be broadly classified into molecular and immunological assays. While the former category is centered around real-time PCR, which is currently considered the gold standard of diagnosis, the latter aims to detect viral antigens or antibodies specific to the viral antigens and is yet to be recommended as a stand-alone diagnostic tool. This review aims to provide an update on the different diagnostic modalities that are currently being used in diagnostic laboratories across the world as well as the upcoming methods and challenges associated with each of them. In a rapidly evolving diagnostic landscape with several testing platforms going through various phases of development and/or regulatory clearance, it is prudent that the clinical community familiarizes itself with the nuances of different testing modalities currently being employed for this condition.