RÉSUMÉ
Background & objectives: Vaccination and natural infection can both augment the immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but how omicron infection has affected the vaccine-induced and hybrid immunity is not well studied in Indian population. The present study was aimed to assess the durability and change in responses of humoral immunity with age, prior natural infection, vaccine type and duration with a minimum gap of six months post-two doses with either ChAdOx1 nCov-19 or BBV152 prior- and post-emergence of the omicron variant. Methods: A total of 1300 participants were included in this observational study between November 2021 and May 2022. Participants had completed at least six months after vaccination (2 doses) with either ChAdOx1 nCoV-19 or an inactivated whole virus vaccine BBV152. They were grouped according to their age (? or ?60 yr) and prior exposure of SARS-CoV-2 infection. Five hundred and sixteen of these participants were followed up after emergence of the Omicron variant. The main outcome was durability and augmentation of the humoral immune response as determined by anti-receptor-binding domain (RBD) immunoglobulin G (IgG) concentrations, anti-nucleocapsid antibodies and anti-omicron RBD antibodies. Live virus neutralization assay was conducted for neutralizing antibodies against four variants – ancestral, delta and omicron and omicron sublineage BA.5. Results: Before the omicron surge, serum anti-RBD IgG antibodies were detected in 87 per cent participants after a median gap of eight months from the second vaccine dose, with a median titre of 114 [interquartile range (IQR) 32, 302] BAU/ml. The levels increased to 594 (252, 1230) BAU/ml post- omicron surge (P<0.001) with 97 per cent participants having detectable antibodies, although only 40 had symptomatic infection during the omicron surge irrespective of vaccine type and previous history of infection. Those with prior natural infection and vaccination had higher anti-RBD IgG titre at baseline, which increased further [352 (IQR 131, 869) to 816 (IQR 383, 2001) BAU/ml] (P<0.001). The antibody levels remained elevated after a mean time gap of 10 months, although there was a decline of 41 per cent. The geometric mean titre was 452.54, 172.80, 83.1 and 76.99 against the ancestral, delta, omicron and omicron BA.5 variants in the live virus neutralization assay. Interpretation & conclusions: Anti-RBD IgG antibodies were detected in 85 per cent of participants after a median gap of eight months following the second vaccine dose. Omicron infection probably resulted in a substantial proportion of asymptomatic infection in the first four months in our study population and boosted the vaccine-induced humoral immune response, which declined but still remained durable over 10 months
RÉSUMÉ
Background & objectives: The treatment outcomes under national antiretroviral therapy (ART) programme are being evaluated in some ART centres in the country. We carried out this study to analyze the impact of first line antiretroviral therapy in HIV infected patients attending a free ART roll out national programme clinic in Pune, India. Methods: Antiretroviral naive HIV infected patients attending the clinic between December 2005 and April 2008 and followed up till March 31, 2011 were included in the analysis. The enrolment and follow up of these patients were done as per the national guidelines. Viral load estimations were done in a subset of patients. Results: One hundred and forty two patients with median CD4 count of 109 cells/μl (IQR: 60-160) were initiated on treatment. The median follow up was 44 months (IQR: 37-53.3 months). Survival analysis showed that the probability of being alive at the end of 5 years was 85 per cent. Overall increase in the median CD4 count was statistically significant (P<0.001). It was significant in patients with >95 per cent adherence (P<0.001). In 14 per cent patients, the absolute CD4 count did not increase by 100 or more cells/μl at the end of 12 months. Viral load estimation in a subset of 68 patients showed undetectable levels in 61 (89.7%) patients after a median duration of 46 months (IQR: 38.3-54.8). Interpretation & conclusions: The first line treatment was effective in patients attending the programme clinic. The adherence level influenced immunological and virological outcomes of patients.
RÉSUMÉ
Although a plethora of molecules have been implicated in the development of HIV associated dementia (HAD), the identity of the indispensable ones is still elusive. The action of various molecules appears to follow a cascade path with one molecule activating another thereby regulating the expression and modulation of the regulatory machineries. Two pathways have been proposed leading to HIV-induced central nervous system (CNS) injury. First involving neurotoxic effect of viral proteins and second, with immunomodulatory substances secreted by the infected cells playing vital role. The viral transfer from infected cells (for example, cells representing macrophage-microglial lineage) to uninfected cells (such as same cell type or nerve cells) occurring perhaps via virological synapse is also not well documented. While the mechanism underlying transfer of HIV-1 through blood-brain barrier is not clearly understood, macrophage-microglial cell lineages are undisputedly predominant cell types that HIV uses for transmission in CNS. The present review describes existing knowledge of the modus operandi of HIV-induced neuropathogenesis gathered through research evidences. of HIV-induced neuropathogenesis gathered through research Mechanisms by which regulatory molecules exploit such cell types in promoting neuropathogenesis would provide key insights in intersecting pathway(s) for designing intervention strategies.