Neutralizing antibody responses to SARS-CoV-2 Omicron variants: Post six months following two-dose & three-dose vaccination of ChAdOx1 nCoV-19 or BBV152.

BACKGROUND OBJECTIVES: The Omicron sub-lineages are known to have higher infectivity, immune escape and lower virulence. During December 2022 - January 2023 and March - April 2023, India witnessed increased SARS-CoV-2 infections, mostly due to newer Omicron sub-lineages. With this unprecedented rise in cases, we assessed the neutralization potential of individuals vaccinated with ChAdOx1 nCoV (Covishield) and BBV152 (Covaxin) against emerging Omicron sub-lineages. METHODS: Neutralizing antibody responses were measured in the sera collected from individuals six months post-two doses (n=88) of Covishield (n=44) or Covaxin (n=44) and post-three doses (n=102) of Covishield (n=46) or Covaxin (n=56) booster dose against prototype B.1 strain, lineages of Omicron; XBB.1, BQ.1, BA.5.2 and BF.7. RESULTS: The sera of individuals collected six months after the two-dose and the three-dose demonstrated neutralizing activity against all variants. The neutralizing antibody (NAbs) level was highest against the prototype B.1 strain, followed by BA5.2 (5-6 fold lower), BF.7 (11-12 fold lower), BQ.1 (12 fold lower) and XBB.1 (18-22 fold lower). INTERPRETATION CONCLUSIONS: Persistence of NAb responses was comparable in individuals with two- and three-dose groups post six months of vaccination. Among the Omicron sub-variants, XBB.1 showed marked neutralization escape, thus pointing towards an eventual immune escape, which may cause more infections. Further, the correlation of study data with complete clinical profile of the participants along with observations for cell-mediated immunity may provide a clear picture for the sustained protection due to three-dose vaccination as well as hybrid immunity against the newer variants.

Needle-free injection system delivery of ZyCoV-D DNA vaccine demonstrated improved immunogenicity and protective efficacy in rhesus macaques against SARS-CoV-2.

The apprehension of needles related to injection site pain, risk of transmitting bloodborne pathogens, and effective mass immunization have led to the development of a needle-free injection system (NFIS). Here, we evaluated the efficacy of the NFIS and needle injection system (NIS) for the delivery and immunogenicity of DNA vaccine candidate ZyCoV-D in rhesus macaques against SARS-CoV-2 infection. Briefly, 20 rhesus macaques were divided into 5 groups (4 animals each), that is, I (1 mg dose by NIS), II (2 mg dose by NIS), III (1 mg dose by NFIS), IV (2 mg dose by NFIS) and V (phosphate-buffer saline [PBS]). The macaques were immunized with the vaccine candidates/PBS intradermally on Days 0, 28, and 56. Subsequently, the animals were challenged with live SARS-CoV-2 after 15 weeks of the first immunization. Blood, nasal swab, throat swab, and bronchoalveolar lavage fluid specimens were collected on 0, 1, 3, 5, and 7 days post infection from each animal to determine immune response and viral clearance. Among all the five groups, 2 mg dose by NFIS elicited significant titers of IgG and neutralizing antibody after immunization with enhancement in their titers postvirus challenge. Besides this, it also induced increased lymphocyte proliferation and cytokine response. The minimal viral load post-SARS-CoV-2 challenge and significant immune response in the immunized animals demonstrated the efficiency of NFIS in delivering 2 mg ZyCoV-D vaccine candidate.

Cost estimation of COVID Kavach test developed in 2020: A National Reference Laboratory initiative during early phase of Indian pandemic mitigation.

BACKGROUND OBJECTIVES: A new indigenously developed technology, coronavirus disease (COVID) Kavach, an IgG immunoglobulin-based enzyme-linked immunosorbent assay (ELISA) kit, was developed in 2020 by the Indian Council of Medical Research-National Institute of Virology (ICMR-NIV), Pune, India. The primary objective of this study was to determine the total cost of development of COVID Kavach IgG ELISA and estimate the unit cost (UC) as well. METHODS: The total development cost (TDC) of COVID Kavach and its UC during the early phase of pandemic mitigation were estimated through a micro-costing approach from provider's perspective. An activity-based bottom-up costing approach was used to facilitate data collection from all resources, and analysis was performed using Microsoft Excel version 2016. The micro-costing data were utilized to interpret the breakdown of cost across all inputs and different levels of activity. RESULTS: The TDC of COVID Kavach was estimated to be JOURNAL/ijmer/04.03/02223309-202310000-00007/363FF04/v/2023-11-25T134903Z/r/image-tiff 2,884,032 (US$ 38,265). The UC of providing test results for exposure to severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) was estimated to be JOURNAL/ijmer/04.03/02223309-202310000-00007/363FF04/v/2023-11-25T134903Z/r/image-tiff 300 (US$ 4) during July 2020. The capital and recurrent cost were incurred around 5-10 per cent and 90-95 per cent, respectively, in both the development and UC of COVID Kavach. The major portion of funds (70-80%) was utilized for procurement of laboratory consumables, followed by human resources (8-12%) in the development as well as for UC of COVID Kavach. INTERPRETATION CONCLUSIONS: The estimates from this study can be useful for conducting economic evaluations, which will help in deciding upon the subsidy in government health facilities. The data may be useful to set up laboratory facilities analogous to the National Reference Laboratory located at the ICMR-NIV, Pune and for allotting sufficient budget to develop such assays in government-funded laboratories.

Performance assessment of seven SARS-CoV-2 IgG enzyme-linked immunosorbent assays.

The pandemic of COVID-19 has caused enormous fatalities worldwide. Serological assays are important for detection of asymptomatic or mild cases of COVID-19, and sero-prevalence and vaccine efficacy studies. Here, we evaluated and compared the performance of seven commercially available enzyme-linked immunosorbent assay (ELISA)s for detection of anti-severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) immunoglobulin G (IgG). The ELISAs were evaluated with a characterized panel of 100 serum samples from qRT-PCR confirmed COVID-19 patients, collected 14 days post onset disease, 100 SARS-CoV-2 negative samples and compared the results with that of neutralization assay. Results were analysed by creating the receiver operating characteristic curve of all the assays in reference to the neutralization assay. All kits, were found to be suitable for detection of IgG against SARS-CoV-2 with high accuracy. The DiaPro COVID-19 IgG ELISA showed the highest sensitivity (98%) among the kits. The assays demonstrated high sensitivity and specificity in detecting the IgG antibodies against SARS-CoV-2. However, the presence of IgG antibodies does not always correspond to neutralizing antibodies. Due to their good accuracy indices, these assays can also aid in tracing mild infections, in cohort studies and in pre-vaccine evaluations.

Neutralizing antibody responses to SARS-CoV-2 in COVID-19 patients.

BACKGROUND & OBJECTIVES: The global pandemic caused by SARS-CoV-2 virus has challenged public health system worldwide due to the unavailability of approved preventive and therapeutic options. Identification of neutralizing antibodies (NAb) and understanding their role is important. However, the data on kinetics of NAb response among COVID-19 patients are unclear. To understand the NAb response in COVID-19 patients, we compared the findings of microneutralization test (MNT) and plaque reduction neutralization test (PRNT) for the SARS-CoV-2. Further, the kinetics of NAb response among COVID-19 patients was assessed. METHODS: A total of 343 blood samples (89 positive, 58 negative for SARS-CoV-2 and 17 cross-reactive and 179 serum from healthy individuals) were collected and tested by MNT and PRNT. SARS-CoV-2 virus was prepared by propagating the virus in Vero CCL-81 cells. The intra-class correlation was calculated to assess the correlation between MNT and PRNT. The neutralizing endpoint as the reduction in the number of plaque count by 90 per cent (PRNT90) was also calculated. RESULTS: The analysis of MNT and PRNT quantitative results indicated that the intra-class correlation was 0.520. Of the 89 confirmed COVID-19 patients, 64 (71.9%) showed NAb response. INTERPRETATION & CONCLUSIONS: The results of MNT and PRNT were specific with no cross-reactivity. In the early stages of infection, the NAb response was observed with variable antibody kinetics. The neutralization assays can be used for titration of NAb in recovered/vaccinated or infected COVID-19 patients.

Development of indigenous IgG ELISA for the detection of anti-SARS-CoV-2 IgG.

BACKGROUND & OBJECTIVES: Since the beginning of the year 2020, the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impacted humankind adversely in almost all spheres of life. The virus belongs to the genus Betacoronavirus of the family Coronaviridae. SARS-CoV-2 causes the disease known as coronavirus disease 2019 (COVID-19) with mild-to-severe respiratory illness. The currently available diagnostic tools for the diagnosis of COVID-19 are mainly based on molecular assays. Real-time reverse transcription-polymerase chain reaction is the only diagnostic method currently recommended by the World Health Organization for COVID-19. With the rapid spread of SARS-CoV-2, it is necessary to utilize other tests, which would determine the burden of the disease as well as the spread of the outbreak. Considering the need for the development of such a screening test, an attempt was made to develop and evaluate an IgG-based ELISA for COVID-19. METHODS: A total of 513 blood samples (131 positive, 382 negative for SARS-CoV-2) were collected and tested by microneutralization test (MNT). Antigen stock of SARS-CoV-2 was prepared by propagating the virus in Vero CCL-81 cells. An IgG capture ELISA was developed for serological detection of anti-SARS-CoV-2 IgG in serum samples. The end point cut-off values were determined by using receiver operating characteristic (ROC) curve. Inter-assay variability was determined. RESULTS: The developed ELISA was found to be 92.37 per cent sensitive, 97.9 per cent specific, robust and reproducible. The positive and negative predictive values were 94.44 and 98.14 per cent, respectively. INTERPRETATION & CONCLUSIONS: This indigenously developed IgG ELISA was found to be sensitive and specific for the detection of anti-SARS-CoV-2 IgG in human serum samples. This assay may be used for determining seroprevalence of SARS-CoV-2 in a population exposed to the virus.

Harmonization of Zika serological assays and comparative evaluation of two commercial ZIKA IgG ELISA kits.

The interpretation for Zika virus serology results is challenging due to high antibody cross reactivity with other flaviviruses. This limits availability of reliable and accurate methods for serosurveillance studies to understand the disease burden. Therefore, we conducted study to harmonize anti-Zika IgG antibody detection assays with 1st WHO International Standard (16/352) and working standard (16/320) for anti-Zika virus antibody.Additionally, evaluated NuGenTMZIKA-IgG and NovaLisa®ZIKA virus IgG-Capture ELISA using a panel of 278 seraFurther, 106 samples positive for other-flavi viruses were taken for assessing cross-reactivity of the assay, all serums were further tested by Zika-PRNT. The results of this study indicates satisfactory performance of both the assays. Serological and neutralization assays were calibrated according to the international standards. This will help in understanding antibody dynamics in serosurveillance and vaccine studies. However the performance of the kits with possibilities of cross-reactivity will have to be verified by coupling ZIKV and DENV specific ELISA.

High rates of reinfection and incidence of bacterial sexually transmitted infections in a cohort of female sex workers from two Indian cities: need for different STI control strategies?

BACKGROUND: Female sex workers (FSWs) in India are provided a standardised package of clinical interventions for management of sexually transmitted infections (STIs). A study was conducted among FSWs at known high STI prevalence sites to determine the effectiveness of the service package. METHODS: A cohort of FSW clinic attendees in two cities, Hyderabad and Mumbai, were enrolled and followed up from October 2008 to November 2009. At each visit, behavioural and clinical data were obtained and vaginal swabs collected for laboratory testing of cervical infections (gonorrhoea and chlamydia). RESULTS: 417 participants were enrolled, of whom 360 attended at least a follow-up visit. Prevalence of cervical infections did not change between the baseline and final visits (27.7% and 21.3% respectively, p=0.08) in spite of presumptive treatment at baseline and syndromic management at all visits. The proportion of asymptomatic cervical infections increased from 36% at baseline to 77% at the final visit. Incidence rate of cervical infections was high (85.6/100 person years) and associated with a prevalent cervical infection at baseline (HR=2.7, p<0.001) and inconsistent condom use with non-commercial partners (HR=2.5, p=0.014). CONCLUSIONS: High rates of STIs persisted despite the interventions due to poor condom use, minimal partner treatment, and high prevalence and incidence of STIs with a large proportion of asymptomatic infections. High-prevalence FSW sites in India need to design more effective partner treatment strategies and consider increasing the frequency of presumptive treatment as a temporary measure for quickly reducing STI prevalence, with renewed emphasis on consistent condom use with all partners.

An exploration of elevated HIV and STI risk among male sex workers from India.

BACKGROUND: Men who have sex with men (MSM) who also report transactional sex (male sex workers or MSWs) are known to be at higher risk for HIV and sexually transmitted infections (STIs). The study aimed to profile socio-demographic characteristics and risk factors associated with high HIV prevalence among MSWs. METHODS: A cross-sectional study was conducted in 2008-9 among 483 high-risk MSM who attended STI clinics at Mumbai and Hyderabad, two large cities in India. RESULTS: About 70% of the MSM reported transactional sex. As compared to other MSM, MSWs had more male partners (8.9 versus 2.5, p < 0.001) and higher rates of receptive anal sex (96% versus 72%, p < 0.001). HIV prevalence among MSWs and other MSM was 43.6% and 18.1% respectively. HIV prevalence among MSWs was associated with the place of residence (MSWs from Hyderabad were 7.3 times more likely to be infected), positive syphilis serology (3.8 times) and duration of sex work (increased by 8% for every additional year). CONCLUSION: The study showed that MSWs are at high risk for HIV acquisition/transmission, which highlights the need for intensified interventions for personalized risk-reduction counselling and STI screening. Newer biomedical interventions such as pre-exposure prophylaxis and treatment as prevention could also be considered.

External quality assurance of serological diagnosis of dengue, chikungunya and Japanese encephalitis virus infection.

Introduction: Dengue, chikungunya and Japanese encephalitis are the most common arthropod-borne viral diseases in India. Due to overlapping clinical symptoms, accurate, high-quality and timely laboratory-based differential diagnosis is essential for control and containment of outbreaks. This is most commonly done by detection of IgM antibodies in serum using enzyme-linked immunosorbent assays. The Resource Centre for Virus Research and Diagnostic Laboratories (VRDLs) in Pune, India organized an external quality assurance (EQA) study to check the accuracy of serological diagnostics in the VRDL network. Methods: Three panels, one each for anti-dengue virus, anti-chikungunya virus and anti-Japanese encephalitis virus IgM antibodies, comprising six human serum samples (two positive and four negative) were distributed to test the sensitivity, specificity and reproducibility of serological testing in 124 VRDLs across India in 2018-19 and 2019-20. Results: Among the 124 VRDLs, the average concordance for both 2018-19 and 2019-20 was 98%. In 2018-19, 78.33%, 13.33% and 6.66% of VRDLs reported 100% concordance, 91-99% concordance and 81-90% concordance with the reference results, respectively, and 1.66% of VRDLs had concordance <80%. In 2019-20, 79.68%, 14.06% and 4.68% of VRDLs reported 100% concordance, 91-99% concordance and 81-90% concordance with the reference results, respectively, and 1.56% of VRDLs had concordance <80%. Conclusion: The EQA programme was beneficial for assessing and understanding the performance of the VRDLs. The study data indicate good proficiency in serological diagnosis of dengue, chikungunya and Japanese encephalitis in the VRDL network laboratories. Further expansion of the EQA programme to cover other viruses of public health importance will increase confidence among the VRDL network, and generate evidence of high-quality testing.

Host immune responses in aged rhesus macaques against BBV152, an inactivated SARS-CoV-2 vaccine, and cross-neutralization with beta and delta variants.

The magnitude and duration of immune response to COVID-19 vaccination in older adults are known to be adversely affected due to immunosenescence and inflammaging. The threat of emerging variants warrants studies on immune response in older adults to primary vaccination and booster doses so as to understand the effectiveness of vaccines in countering the threat of emerging variants. Non-human primates (NHPs) are ideal translational models, as the immunological responses in NHPs are similar to those in humans, so it enables us to understand host immune responses to the vaccine. We initially studied humoral immune responses in aged rhesus macaques employing a three-dose regimen of BBV152, an inactivated SARS-CoV-2 vaccine. Initially, the study investigated whether the third dose enhances the neutralizing antibody (Nab) titer against the homologous virus strain (B.1) and variants of concern (Beta and Delta variants) in aged rhesus macaques immunized with BBV152, adjuvanted with Algel/Algel-IMDG (imidazoquinoline). Later, we also attempted to understand cellular immunity in terms of lymphoproliferation against γ-inactivated SARS-CoV-2 B.1 and delta in naïve and vaccinated rhesus macaques after a year of the third dose. Following the three-dose regimen with 6 µg of BBV152 with Algel-IMDG, animals had increased Nab responses across all SARS-CoV-2 variants studied, which suggested the importance of booster dose for the enhanced immune response against SARS-CoV-2-circulating variants. The study also revealed the pronounced cellular immunity against B.1 and delta variants of SARS-CoV-2 in the aged rhesus macaques even after a year of vaccination.

Broadly Reactive SARS-CoV-2-Specific T-Cell Response and Participation of Memory B and T Cells in Patients with Omicron COVID-19 Infection.

January 2022 onward, India witnessed a sudden increase in Omicron COVID-19 infections, having a mild course that prompted us to identify the key host factors/immune molecules modulating disease course/outcomes. The current study evaluated the percentages of lymphocyte subsets by flowcytometry, SARS-CoV-2 specific T-cell immune response by ELISPOT, estimation of plasma cytokine/chemokine levels on a Bio-plex Multiplex Immunoassay System and anti-SARS-CoV-2 IgG levels by enzyme-linked immunosorbent assay in 19 mild Omicron infected patients, 45 mild SARS-CoV-2 (2020) patients and 36 uninfected controls from India. Natural killer cells, B and memory B cells were high in vaccinated and total Omicron-infected patients groups compared to the mild SARS-CoV-2 (2020) patient group, while CD8+ T cells were high in total Omicron-infected patients group compared to the uninfected control group (p < 0.05 each). Omicron-infected patients had T-cell response against SARS-CoV-2 whole virus, S1 proteins (wild type and delta variant) in 10 out of 17 (59%), 10 out of 17 (59%), and 8 out of 17 (47%), respectively. The current study of Omicron-infected patients elucidates broadly reactive antibody, T-cell response, and participation of memory B and T cells induced by vaccination/natural infection. The limited effect of Omicron's mutations on T-cell response is suggestive of protection from severity. Pro-inflammatory IL-6, IFN-γ, chemokines CCL-2, CCL-3, CCL-4, CCL-5, and IL-8 as potential biomarkers of Omicron infection may have future diagnostic importance. The cellular immune response data in Omicron-infected patients with parental Omicron lineage could serve as a starting point to define the readouts of protective immunity against circulating Omicron subvariants.

Duration of seroprotection of the live attenuated SA-14-14-2 Japanese encephalitis vaccine in children in India.

BACKGROUND: Acute encephalitis syndrome (AES) is a major public health concern in India, and the Japanese Encephalitis (JE) virus is the most common cause of viral encephalitis in Asia affecting children under the age of 15 years. In India, despite the introduction of the JE vaccine (SA-14-14-2) in the immunization programme, JE continues to account for 15-20% of AES cases to date. This study evaluates the immunogenicity of live attenuated SA-14-14-2 JE vaccine in terms of persistence of the humoral response after two doses. METHODS: A cross-sectional study was conducted among 266 children belonging to one of the JE endemic regions of Uttar Pradesh, India. Blood samples were taken from children (2-10 years) and grouped according to the duration (in years) after two doses of the vaccine (5 groups with a class interval of 2 years). Informed written consent was obtained from the parents/guardians. All the samples collected were tested for the presence of anti-JEV-specific IgG antibodies by enzyme-linked immunosorbent assay (ELISA) and further confirmed by micro neutralization test (MNT) and immunofluorescence assays. RESULTS: Of the 266 samples tested by ELISA for anti-JEV-specific IgG antibodies, 260 (97.74%) were negative and 6 (2.26%) were equivocal. The geometric mean immune status ratio across the five groups, 0-2 years (n = 59), 2-4 years (n = 73), 4-6 years (n = 65), 6-8 years (n = 48) and 8-10 years (n = 21) post-two doses of SA-14-14-2 JE vaccine was 1.143, 1.059, 1.138, 1.075 and 1.130, respectively, and the geometric mean titre obtained from MNT across the five groups was 10.77, 8.400, 8.453, 9.517 and 9.674, respectively. CONCLUSION: The study showed a decreasing trend of anti-JEV specific IgG antibody titres across the five groups based on the duration following two doses of SA-14-14-2 vaccine. The results emphasize the significance of booster doses of vaccine for children living in endemic areas.

Genital ulcer disease in India: etiologies and performance of current syndrome guidelines.

BACKGROUND: In India, genital ulcer disease (GUD) syndrome is clinically classified as herpetic or nonherpetic and managed accordingly; laboratory support is unavailable at most health facilities. We undertook a study to determine the etiology of GUDs in men presenting to sexually transmitted infection (STI) clinics and assess the performance of the national algorithm for syndromic management of herpetic and nonherpetic GUDs in India. METHOD: A cross-sectional study was conducted among men with complaints of genital ulcers attending 8 STI clinics in 4 states. Ulcer swabs were collected and tested by the multiplex polymerase chain reaction method to determine the etiology of GUD. RESULTS: Of the 194 men recruited, etiology was confirmed in 121 GUD cases (62%). Herpes simplex virus (48%) was the most common etiological agent identified, followed by Treponema pallidum (23%) and mixed infections (9%). One case of Haemophilus ducreyi was confirmed in this series. The overall sensitivity and specificity of the national syndromic management algorithm for GUD were 68% and 52%, respectively. Using the national algorithm, 52 (42%) cases clinically misclassified as either herpetic (18 cases) or nonherpetic (34 cases) GUD resulting in incorrect treatment. CONCLUSIONS: Our findings suggest a revision of existing national STI treatment guidelines in India to include treatment of syphilis infections of all GUD patients. Periodic studies are required to monitor changing spectrum of GUD etiologies in India.