Assessment of Enterovirus Excretion and Identification of VDPVs in Patients with Primary Immunodeficiency in India: Outcome of ICMR-WHO Collaborative Study Phase-I.

The emergence of vaccine-derived polioviruses (VDPVs) in patients with Primary Immunodeficiency (PID) is a threat to the polio-eradication program. In a first of its kind pilot study for successful screening and identification of VDPV excretion among patients with PID in India, enteroviruses were assessed in stool specimens of 154 PID patients across India in a period of two years. A total of 21.42% of patients were tested positive for enteroviruses, 2.59% tested positive for polioviruses (PV), whereas 18.83% of patients were positive for non-polio enteroviruses (NPEV). A male child of 3 years and 6 months of age diagnosed with Hyper IgM syndrome was detected positive for type1 VDPV (iVDPV1) with 1.6% nucleotide divergence from the parent Sabin strain. E21 (19.4%), E14 (9%), E11 (9%), E16 (7.5%), and CVA2 (7.5%) were the five most frequently observed NPEV types in PID patients. Patients with combined immunodeficiency were at a higher risk for enterovirus infection as compared to antibody deficiency. The high susceptibility of PID patients to enterovirus infection emphasizes the need for enhanced surveillance of these patients until the use of OPV is stopped. The expansion of PID surveillance and integration with a national program will facilitate early detection and follow-up of iVDPV excretion to mitigate the risk for iVDPV spread.

Poliovirus surveillance in patients with primary immunodeficiencies, India.

Individuals with primary immunodeficiencies who are infected with vaccine-derived polioviruses may continue to shed poliovirus for months and go undetected by surveillance programmes of acute flaccid paralysis. These patients therefore pose a risk of initiating poliovirus outbreaks that jeopardize efforts towards global polio eradication. To identify these individuals, we designed a study protocol for the establishment of a network for surveillance of immunodeficiency-related vaccine-derived poliovirus in India. In the first step we identified recognized centres in India that could diagnose and enrol patients with primary immunodeficiency disorder into the study. Stool sample collection from study sites, culture, isolation, characterization of enteroviruses and reporting to study sites was carried out at the National Institute of Virology Mumbai Unit, as per the WHO national polio surveillance project protocol. In the first phase of the study from January 2020 to December 2021, we implemented the protocol at seven study sites at different medical institutes to determine the proportion of poliovirus infections in primary immunodeficiency disorder patients of India. We later expanded the study by including an additional 14 medical institutes across the country in the second phase running from January 2022 to December 2023. We believe this study protocol will help other countries to initiate immunodeficiency-related vaccine-derived poliovirus surveillance to identify and follow up patients who are long-term excretors of vaccine-derived poliovirus. Integration of immunodeficiency-related poliovirus surveillance with acute flaccid paralysis surveillance of the existing poliovirus network will enhance continuous screening of patients with primary immunodeficiency disorder in the future.

Certains individus qui présentent des immunodéficiences primaires et sont infectés par des poliovirus dérivés d'une souche vaccinale pourraient continuer à excréter le poliovirus pendant des mois sans que ce dernier ne soit détecté par le biais d'une surveillance de la paralysie flasque aiguë. Ces patients risquent donc de déclencher des épidémies de poliovirus qui mettent en péril les efforts visant à éradiquer la poliomyélite dans le monde. En vue d'identifier ces individus, nous avons élaboré un protocole d'étude pour établir, en Inde, un réseau de surveillance du poliovirus d'origine vaccinale lié à une immunodéficience. Au cours de la première étape, nous avons repéré des centres reconnus dans le pays, capables de diagnostiquer des patients atteints d'un syndrome d'immunodéficience primaire et de les recruter dans le cadre de l'étude. Le prélèvement des échantillons de selles auprès des sites participant à l'étude, la culture, l'isolement, la caractérisation des entérovirus et la communication des résultats à ces sites ont été pris en charge par le National Institute of Virology Mumbai Unit, conformément au protocole du Projet national de surveillance de la poliomyélite de l'OMS. Nous avons consacré la première phase de l'étude, qui s'est déroulée entre janvier 2020 et décembre 2021, à la mise en œuvre du protocole au sein de différents établissements médicaux sur sept sites participants, afin de déterminer le nombre d'infections au poliovirus chez les patients souffrant d'un syndrome d'immunodéficience primaire en Inde. Nous avons ensuite, durant la deuxième phase comprise entre janvier 2022 et décembre 2023, élargi l'étude en incluant 14 établissements supplémentaires à travers le pays. Nous sommes convaincus que ce protocole d'étude aidera d'autres pays à instaurer une surveillance du poliovirus dérivé d'une souche vaccinale et lié à une immunodéficience, qui leur servira à identifier et suivre les patients responsables d'une excrétion prolongée du poliovirus d'origine vaccinale. L'intégration, au sein du réseau existant dédié au poliovirus, d'une surveillance de ce type couplée à une surveillance de la paralysie flasque aiguë améliorera le dépistage systématique des patients atteints d'un syndrome d'immunodéficience primaire à l'avenir.

Las personas con inmunodeficiencias primarias infectadas por los poliovirus de origen vacunal pueden seguir excretando poliovirus durante meses sin que la vigilancia de la parálisis flácida aguda los detecte. Por lo tanto, estos pacientes suponen un riesgo de iniciar brotes de poliovirus que pongan en peligro los esfuerzos hacia la erradicación mundial de la poliomielitis. Para identificar a estas personas, diseñamos un protocolo de estudio para el establecimiento de una red de vigilancia de poliovirus de origen vacunal relacionados con inmunodeficiencias en la India. En el primer paso identificamos centros reconocidos en la India que pudieran diagnosticar e inscribir en el estudio a pacientes con trastorno de inmunodeficiencia primaria. La recogida de muestras de heces de los centros de estudio, el cultivo, el aislamiento, la caracterización de los enterovirus y la notificación a los centros de estudio se llevaron a cabo en el Instituto Nacional de Virología, Unidad de Mumbai, según el protocolo del Proyecto Nacional de Vigilancia de la Poliomielitis de la OMS. En la primera fase del estudio, de enero de 2020 a diciembre de 2021, aplicamos el protocolo en siete centros de estudio de diferentes institutos médicos para determinar la proporción de infecciones por poliovirus en pacientes con trastorno de inmunodeficiencia primaria de la India. A continuación, ampliamos el estudio con la inclusión de otros 14 institutos médicos de todo el país en la segunda fase, de enero de 2022 a diciembre de 2023. Creemos que este protocolo de estudio ayudará a otros países a iniciar la vigilancia de poliovirus de origen vacunal relacionados con la inmunodeficiencia para identificar y hacer un seguimiento de los pacientes que son excretores a largo plazo de poliovirus de origen vacunal. La integración de la vigilancia del poliovirus asociado a la inmunodeficiencia con la vigilancia de la parálisis flácida aguda de la red de poliovirus existente mejorará el cribado continuo de pacientes con trastorno por inmunodeficiencia primaria en el futuro.

Susceptibility and cytokine responses of human neuronal cells to multiple circulating EV-A71 genotypes in India.

Enterovirus-A71 (EV-A71) associated Hand, foot and mouth disease (HFMD) is a highly contagious viral infection affecting children in Asia-Pacific region and has become a major threat to public health. Although several EV-A71 genotypes (C, D, and G) were isolated in India in recent years, no recognizable outbreak of EV-A71 caused HFMD, Acute Flaccid paralysis (AFP) or encephalitis have been reported so far. It is essential to study the pathogenicity or cell tropism of these Indian isolates in order to understand their tendency to cause disease. We investigated the susceptibility and cytokine responses of indigenous EV-A71 genotypes (D and G) isolated from cases of AFP and genotype C viruses isolated from cases of HFMD and encephalitis, in human cells in-vitro. Although all three EV-A71 genotypes could infect and replicate in human muscle and neuronal cells, the genotype D virus showed a delayed response in human neuronal cells. Quantification of cytokine secretion in response to these isolates followed by confirmation with gene expression assays in human neuronal cells revealed significantly higher secretion of pro-inflammatory cytokines TNF-α IL-8, IL-6, IP-10 (p < 0.001) in G genotype infected cells as compared to pathogenic C genotypes whereas the genotype D virus could not induce any of the inflammatory cytokines. These findings will help to better understand the host response to indigenous EV-A71 genotypes for management of future EV-A71 outbreaks in India, if any.

Expression of innate immune response genes in upper airway samples of SARS-CoV-2 infected patients: A preliminary study.

Background & objectives: Upper respiratory mucosa is the entryway for SARS-CoV-2, and cells at this site form the first line of resistance against the pathogens. Innate immune response at this point is crucial for managing the replication and early stage symptoms of virus infection. This study was aimed to evaluate the expression of pattern recognition receptors and cytokines in upper airway cells of SARS-CoV-2 infected patients. Methods: Forty seven nasopharyngeal swab (NPS) specimens from 25 SARS-CoV-2 infected patients and 22 SARS-CoV-2 negative individuals were investigated for expression of toll-like receptors (TLRs), melanoma differentiation-associated protein 5 (MDA5), NOD-like receptors family pyrin domain containing 3 (NLRP3), angiotensin-converting enzyme 2 (ACE2), interleukin (IL) - 6, tumour necrosis factor alpha (TNFα) and type-1 interferons (IFNs) by real time reverse transcription polymerase chain reaction. Results: Increased expression of TLR2, MDA5 and ACE2 was detected in SARS-CoV-2 infected patients in comparison with controls. MDA5 expression was significantly higher in asymptomatic and mildly symptomatic SARS-CoV-2 positive patients than the patients with severe symptoms. The asymptomatic group showed significant induction of type 1 IFNs than the symptomatic group. Non-specific induction of TLR7 could be observed in nasopharyngeal (NP) cells irrespective of symptoms and SARS-CoV-2 positivity. Interpretation & conclusions: The findings suggest that increased MDA5 in NP cells of asymptomatic SARS-CoV-2 positive patients may subsequently induce type 1 IFNs to protect the individuals from further clinical severity of SARS-CoV-2 infection. A future prospective study in NPS of larger cohort needs to be performed to confirm our findings.

Natural Clearance of Prolonged VDPV Infection in a Child With Primary Immunodeficiency Disorder.

The emergence of immunodeficiency-associated vaccine-derived polioviruses (iVDPV) from children with primary immunodeficiency disorders poses a threat to the eradication program. Herein, we report a patient with severe combined immunodeficiency (SCID), identified as a prolonged serotype 3 iVDPV (iVDPV3) excreter with 13 VDPV3 isolates and a maximum of 10.33% nucleotide divergence, who abruptly cleared infection after a period of 2 years. Occurrence of an episode of norovirus diarrhea associated with increased activated oligoclonal cytotoxic T cells, inverse CD4:CD8 ratio, significantly elevated pro-inflammatory cytokines, and subsequent clearance of the poliovirus suggests a possible link between inflammatory diarrheal illness and clearance of iVDPV. Our findings suggest that in the absence of B cells and sufficiently activated T/NK cells, macrophages and other T cells may produce auto-inflammatory conditions by TLR/RLR ligands expressed by previous/ongoing bacterial or viral infections to clear VDPV infection. The study highlights the need to screen all the patients with combined immunodeficiency for poliovirus excretion and intermittent follow-up of their immune parameters if found positive, in order to manage the risk of iVDPV excretion in the polio eradication endgame strategy.

Poliovirus Excretion in Children with Primary Immunodeficiency Disorders, India.

Prolonged excretion of poliovirus can occur in immunodeficient patients who receive oral polio vaccine, which may lead to propagation of highly divergent vaccine-derived polioviruses (VDPVs), posing a concern for global polio eradication. This study aimed to estimate the proportion of primary immunodeficient children with enterovirus infection and to identify the long-term polio/nonpolio enterovirus excreters in a tertiary care unit in Mumbai, India. During September 2014-April 2017, 151 patients received diagnoses of primary immunodeficiency (PID). We isolated 8 enteroviruses (3 polioviruses and 5 nonpolio enteroviruses) in cell culture of 105 fecal samples collected from 42 patients. Only 1 patient with severe combined immunodeficiency was identified as a long-term VDPV3 excreter (for 2 years after identification of infection). Our results show that the risk of enterovirus excretion among children in India with PID is low; however, systematic screening is necessary to identify long-term poliovirus excreters until the use of oral polio vaccine is stopped.

Serum IgG and IgA levels in polio and non-polio acute flaccid paralysis cases in western Uttar Pradesh, India.

OBJECTIVE: IgG and IgA immunocompetence of children with wild poliovirus poliomyelitis and non-polio acute flaccid paralysis. METHODS: 932 cases of acute flaccid paralysis, reported in 2008-2009, were tested for presence of polio and non-polio enteroviruses according to the WHO standards. Serum IgA and IgG levels were determined by sandwich ELISA. RESULTS: Mean (SD) IgA levels [0.87 (0.62)g/L; n=28] of virologically confirmed poliomyelitis cases were lower than those of virus negative [1.21 (0.83)g/L; n=612] and non-polio Enterovirus positive [1.22 (0.79)g/L; n=240] cases of acute flaccid paralysis. No significant difference was observed in the concentration of IgG among these groups. CONCLUSIONS: IgA plays an important role in protection against poliomyelitis.

Investigation of the prevalence of antibody immunodeficiency in a polio endemic area in India.

BACKGROUND: Protection against paralytic poliomyelitis is provided mainly by antibody mediated host defense. Despite intensive oral polio vaccine (OPV) immunization campaigns wild poliovirus transmission could not be stopped in Uttar Pradesh (UP) and Bihar states of India by the end of 2010. The objective of our study was to quantitate serum IgG and IgA in children of western UP, India, to determine the prevalence of antibody immunodeficiency. METHODS: A cross-sectional survey for IgG and IgA concentrations in serum samples from healthy children and children with acute flaccid paralysis (AFP), up to the age of 5 years, was performed using sandwich ELISA. RESULTS: The overall mean IgG concentration for 1882 children of western UP, India, was 10.57 ± 4.53 (SD) g/L and mean IgA concentration for 979 children was 1.2 ± 0.818 g/L. Two 7-month-old female children had IgG levels below 2 g/L and there was an absence of neutralizing polio antibodies. The mean serum IgG level of children with AFP (n=979) was lower than levels observed in healthy children (n=903). The proportion of children with IgG levels below 2 g/L and IgA levels below 0.07 g/L was 0.7% in both healthy children and AFP cases. CONCLUSIONS: There was no abnormal prevalence of immunodeficiency in children in western UP which could have delayed achieving the eradication of polio in the state. The immunoglobulin levels reported here may be used as age-specific normal values for Indian children.

Differential induction of Toll-like receptors & type 1 interferons by Sabin attenuated & wild type 1 polioviruses in human neuronal cells.

BACKGROUND & OBJECTIVES: Polioviruses are the causative agent of paralytic poliomyelitis. Attenuated polioviruses (Sabin oral poliovirus vaccine strains) do not replicate efficiently in neurons as compared to the wild type polioviruses and therefore do not cause disease. This study was aimed to investigate the differential host immune response to wild type 1 poliovirus (wild PV) and Sabin attenuated type 1 poliovirus (Sabin PV) in cultured human neuronal cells. METHODS: By using flow cytometry and real time PCR methods we examined host innate immune responses and compared the role of toll like receptors (TLRs) and cytoplasmic RNA helicases in cultured human neuronal cells (SK-N-SH) infected with Sabin PV and wild PV. RESULTS: Human neuronal cells expressed very low levels of TLRs constitutively. Sabin PV infection induced significantly higher expression of TLR3, TLR7 and melanoma differentiation-associated protein-5 (MDA-5) m-RNA in neuronal cells at the beginning of infection (up to 4 h) as compared to wild PV. Further, Sabin PV also induced the expression of interferon α/ß at early time point of infection. The induced expression of IFN α/ß gene by Sabin PV in neuronal cells could be suppressed by inhibiting TLR7. INTERPRETATION & CONCLUSIONS: Neuronal cell innate immune response to Sabin and wild polioviruses differ significantly for TLR3, TLR7, MDA5 and type 1 interferons. Effects of TLR7 activation and interferon production and Sabin virus replication in neuronal cells need to be actively investigated in future studies.

Protective immunity in human filariasis: a role for parasite-specific IgA responses.

BACKGROUND: Filaria-specific antibodies of immunoglobulin (Ig) G, IgE, and IgM isotypes have been correlated with acquired immunity in the literature, but the status of filaria-specific IgA and its role in human filariasis has not been addressed. The present study attempts to fill this lacuna. METHODS: Both total and filaria-specific IgA to different developmental stages of filarial parasites were quantified by solid-phase immunoassays in 412 clinically and parasitologically defined cases occurring in an area endemic for human bancroftian filariasis in Orissa, India. RESULTS: Compared with other clinical categories, microfilariae carriers were deficient in total as well as filaria-specific IgA. More crucially, significantly high levels were observed in putatively immune control subjects from areas of endemicity. These associations were also related to sex; female subjects in each category displayed higher levels of filaria-specific IgA than did male subjects. CONCLUSION: The study demonstrates, for the first time, a positive correlation between protective immunity and increased levels of filaria-specific IgA in human bancroftian filariasis. Furthermore, filaria-specific IgA appears to be an immunological window for the sex-related differences in susceptibility to infection observed in human filariasis.

Toll-like receptors and cytokines as surrogate biomarkers for evaluating vaginal immune response following microbicide administration.

Topical microbicides are intended for frequent use by women in reproductive age. Hence, it is essential to evaluate their impact on mucosal immune function in the vagina. In the present study, we evaluated nisin, a naturally occurring antimicrobial peptide (AMP), for its efficacy as an intravaginal microbicide. Its effect on the vaginal immune function was determined by localizing Toll-like receptors (TLRs-3, 9) and cytokines (IL-4, 6 , 10 and TNF-alpha) in the rabbit cervicovaginal epithelium following intravaginal administration of high dose of nisin gel for 14 consecutive days. The results revealed no alteration in the expression of TLRs and cytokines at both protein and mRNA levels. However, in SDS gel-treated group, the levels were significantly upregulated with the induction of NF-kappaB signalling cascade. Thus, TLRs and cytokines appear as sensitive indicators for screening immunotoxic potential of candidate microbicides.

Protective immunity in human lymphatic filariasis: problems and prospects.

Human filariasis caused by lymphatic dwelling nematodes, affecting 120 million persons worldwide, is a major public health problem. Efforts towards development of vaccines for such large tissue-dwelling nematodes depends significantly on identification and demonstration of protective immunity in the exposed population. Immunological studies conducted in human filariasis so far are essentially attempts to establish a correlation of the immune response phenotypes with presence or absence of filarial infections/disease in the host, and the cause-effect relationship between the observed immune responses in the host and protective immunity continues to be conjectural. This short review attempts to clarify the functional definition of protective immunity, problems associated with identification of putatively immune subjects in endemic areas, role of antibodies reactive to surface of microfilariae and larvae stages of filarial parasites and importance of undertaking immunological investigations on a longitudinal basis in different cohorts of subjects presenting with one or the features of infection and/or disease for more accurate delineation of protective immunity in human filariasis.

Deficiency of antibody responses to T-independent antigens in gerbils---Meriones unguiculatus.

Meriones unguiculatus commonly known as gerbils are widely used as animal models for a variety of parasitic infections such as Brugia malayi, Entamoeba histolytica, Giardia duodenalis, Toxoplasma gondi, Helicobacter pylori, Strongyloides stercoralis and Echinococcus multilocularis. Groups of BALB/c mice, gerbils and XID mice were studied for antibody responses to T-independent antigens. Gerbils were found to be significantly deficient in eliciting antibodies to both dextran and phosphorylcholine (PC) in comparison to BALB/c mice. The antibody response of gerbils to T-independent antigens was found to be similar to the response observed in Bruton's tyrosine kinase (Btk) deficient XID mice, which are known to be poor responders to T-independent antigens. Similar to XID mice, normal gerbil sera were found to be deficient in naturally occurring antibodies to single stranded DNA (SS-DNA), lipopolysaccharide (LPS) and phospholipids. This raises the possibility of a deficiency of CD5+ B-lymphocytes (also known as B-1 cells) in gerbils, since deficiency of this sub-population of B-lymphocytes has been attributed to the absence of such naturally occurring antibodies in XID mice. These results indicate the need to study immunogenicity of parasite T-independent antigens and their relationship to protective immunity in parasitic infections in gerbils.