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Ajit P Singh

Bio: Ajit P Singh is an academic researcher from Panacea Biotec. The author has contributed to research in topics: Virology & Outbreak. The author has an hindex of 3, co-authored 3 publications receiving 239 citations.
Topics: Virology, Outbreak, Antibody, Chickenpox, Monkeypox

Papers
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Journal ArticleDOI
TL;DR: A randomised, double-blind, controlled trial to assess the immunogenicity of a novel bivalent types 1 and 3 oral poliovirus vaccine and the superiority of monovalent type 2 OPV over trivalent OPV, and the non-inferiority of bivalent vaccine compared with mopV1 and mOPV3.

139 citations

Journal ArticleDOI
TL;DR: Assessing the current immunity profile after routine doses of trivalent oral poliovirus vaccine (OPV) and numerous supplemental doses of type-1 monovalent OPV (mOPV1), and compared the effect of five vaccine formulations and dosages on residual immunity gaps found almost total seroprevalence against poliov virus type 1, which is consistent with recent absence of poliomyelitis cases.
Abstract: Summary Background The continued presence of polio in northern India poses challenges to the interruption of wild poliovirus transmission and the management of poliovirus risks in the post-eradication era. We aimed to assess the current immunity profile after routine doses of trivalent oral poliovirus vaccine (OPV) and numerous supplemental doses of type-1 monovalent OPV (mOPV1), and compared the effect of five vaccine formulations and dosages on residual immunity gaps. Methods We did a community-based, randomised controlled trial of healthy infants aged 6–9 months at ten sites in Moradabad, India. Serum neutralising antibody was measured before infants were randomly assigned to a study group and given standard-potency or higher-potency mOPV1, intradermal fractional-dose inactivated poliovirus vaccine (IPV, GlaxoSmithKline), or intramuscular full-dose IPV from two different manufacturers (GlaxoSmithKline or Panacea). Follow-up sera were taken at days 7 and 28. Our primary endpoint was an increase of more than four times in antibody titres. We did analyses by per-protocol in children with a blood sample available before, and 28 days after, receiving study vaccine (or who completed study procedures). This trial is registered with Current Controlled Trials, number ISRCTN90744784. Findings Of 1002 children enrolled, 869 (87%) completed study procedures (ie, blood sample available at day 0 and day 28). At baseline, 862 (99%), 625 (72%), and 418 (48%) had detectable antibodies to poliovirus types 1, 2, and 3, respectively. In children who were type-1 seropositive, an increase of more than four times in antibody titre was detected 28 days after they were given standard-potency mOPV1 (5/13 [38%]), higher-potency mOPV1 (6/21 [29%]), intradermal IPV (9/16 [56%]), GlaxoSmithKline intramuscular IPV (19/22 [86%]), and Panacea intramuscular IPV (11/13 [85%]). In those who were type-2 seronegative, 42 (100%) of 42 seroconverted after GlaxoSmithKline intramuscular IPV, and 24 (59%) of 41 after intradermal IPV (p Interpretation Supplemental mOPV1 resulted in almost total seroprevalence against poliovirus type 1, which is consistent with recent absence of poliomyelitis cases; whereas seroprevalence against types 2 and 3 was expected for routine vaccination histories. The immunogenicity of IPV produced in India (Panacea) was similar to that of an internationally manufactured IPV (GSK). Intradermal IPV was less immunogenic. Funding Global Alliance for Vaccines and Immunization (GAVI), WHO.

90 citations

Journal ArticleDOI
05 Aug 2011-Vaccine
TL;DR: In both studies, seronconversion rates were unexpectedly low to poliovirus type 1 after mOPV1 or tOPV given at birth but high for all formulations of mopV1 given at age 30 days.

23 citations

Journal ArticleDOI
TL;DR: The research shows smallpox symptoms and signs are similar to those of human monkey pox, showing a need for additional research into the biology, ecology, and epidemiology of the virus in endemic areas.
Abstract: A zoonotic orthopoxvirus called human monkey pox has symptoms that resemble smallpox. It is challenging to clinically distinguish the condition from varicella and smallpox. The identification and surveillance of diseases rely heavily on laboratory diagnostics, and novel tests are required for a quicker and more accurate diagnosis. The bulk of human infections occur in Central Africa, where surveillance in underdeveloped rural regions can be challenging but is possible with the help of technologies that are evidence-based and materials that teach public health professionals about key concepts. Now that smallpox immunization is not a common practice, epidemiological studies are required. For the treatment and averting monkey pox, new medications and vaccines provide hope. They need more study before they can be used in an endemic environment, though. To better understand and prevent human infections, there is a need for additional research into the biology, ecology, and epidemiology of the virus in endemic areas. The research shows smallpox symptoms and signs are similar to those of human monkey pox. The virus that causes monkey pox can alter the genetic makeup of the virus, ecological changes, and host behaviour, raising concerns that it may evolve into a more dangerous illness in humans. Humans can contract the virus by being bitten by an infected animal, coming into contact with its blood, body fluids, or fur, or by petting infected animals. Meat that has been inadequately processed from a sick animal may be contagious. Humans can catch the virus by touching an infected person's skin blisters or scabs, coming into contact with cough droplets, or by using bedding, clothing, or towels that have been worn by someone who has a rash. Moreover, experts believe sexual contact can also spread the infection.
Journal ArticleDOI
TL;DR: In this article , a cell culture-based indirect ELISA was developed that demonstrated an accuracy of 88.8% compared to VNT and 100% sensitivity with 66.67% specificity, could identify 61.71% seroprevalence of swinepox in random pig serum samples.
Abstract: Background: Swinepox is an economically important, classical pox disease of piglets. The present study was undertaken with a view to develop rapid serological tests to diagnose the disease. Methods: During the study period, 25 suspected swinepox outbreaks in Assam were confirmed by polymerase chain reaction with sequencing and phylogenetic analysis, further the outbreaks were confirmed by transmission electron microscopy (TEM) for identification of swinepox positive samples. The positive samples were used to isolate the virus in PK-15 cell line and develop indirect and sandwich ELISA. Result: The cell culture-based indirect ELISA was developed that demonstrated an accuracy of 88.8% compare to VNT and 100% sensitivity with 66.67% specificity, could identify 61.71% seroprevalence of swinepox in random pig serum samples. A sandwich ELISA was also developed with polyclonal sera raised in rabbits as coating antibody and swinepox positive pig serum as tracing antibody. The sandwich ELISA detected 77.78% positive cases compared to PCR. Swinepox is an emerging disease in North-eastern region with high sero-positivity observed during random sampling. This is the first report of using immune sorbent assays to detect swinepox.

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Journal ArticleDOI
TL;DR: Although substantial effectiveness and safety data exist on the use and delivery of OPV and IPV, several new research initiatives are currently underway to fill specific knowledge gaps to inform future vaccination policies that would assure polio is eradicated and eradication is maintained.
Abstract: Live attenuated oral polio vaccine (OPV) and inactivated polio vaccine (IPV) are the tools being used to achieve eradication of wild polio virus. Because OPV can rarely cause paralysis and generate revertant polio strains, IPV will have to replace OPV after eradication of wild polio virus is certified to sustain eradication of all polioviruses. However, uncertainties remain related to IPV's ability to induce intestinal immunity in populations where fecal–oral transmission is predominant. Although substantial effectiveness and safety data exist on the use and delivery of OPV and IPV, several new research initiatives are currently underway to fill specific knowledge gaps to inform future vaccination policies that would assure polio is eradicated and eradication is maintained.

194 citations

Journal ArticleDOI
TL;DR: It is estimated from the poliomyelitis case count and the paralytic case-to-infection ratio for type 2 wild poliovirus infections that ∼700,000 cVDPV2 infections have occurred during the outbreak.
Abstract: Since 2005, a large poliomyelitis outbreak associated with type 2 circulating vaccine-derived poliovirus (cVDPV2) has occurred in northern Nigeria, where immunization coverage with trivalent oral poliovirus vaccine (tOPV) has been low. Phylogenetic analysis of P1/capsid region sequences of isolates from each of the 403 cases reported in 2005 to 2011 resolved the outbreak into 23 independent type 2 vaccine-derived poliovirus (VDPV2) emergences, at least 7 of which established circulating lineage groups. Virus from one emergence (lineage group 2005-8; 361 isolates) was estimated to have circulated for over 6 years. The population of the major cVDPV2 lineage group expanded rapidly in early 2009, fell sharply after two tOPV rounds in mid-2009, and gradually expanded again through 2011. The two major determinants of attenuation of the Sabin 2 oral poliovirus vaccine strain (A 481 in the 5′-untranslated region [5′-UTR] and VP1-Ile 143 ) had been replaced in all VDPV2 isolates; most A 481 5′-UTR replacements occurred by recombination with other enteroviruses. cVDPV2 isolates representing different lineage groups had biological properties indistinguishable from those of wild polioviruses, including efficient growth in neuron-derived HEK293 cells, the capacity to cause paralytic disease in both humans and PVR-Tg21 transgenic mice, loss of the temperature-sensitive phenotype, and the capacity for sustained person-to-person transmission. We estimate from the poliomyelitis case count and the paralytic case-to-infection ratio for type 2 wild poliovirus infections that ∼700,000 cVDPV2 infections have occurred during the outbreak. The detection of multiple concurrent cVDPV2 outbreaks in northern Nigeria highlights the risks of cVDPV emergence accompanying tOPV use at low rates of coverage in developing countries.

144 citations

Journal ArticleDOI
TL;DR: Israel was certified as polio-free country in June 2002, but wild-type polio virus ₁ (WPV₁) was isolated initially from routine sewage samples collected between 7 and 13 April 2013 in two cities in the Southern district, and WPV-specific analysis of samples indicated WPV⁁ introduction into that area in early February 2013.
Abstract: Israel was certified as polio-free country in June 2002, along with the rest of the World Health Organization European Region. Some 11 years later, wild-type polio virus ₁ (WPV₁) was isolated initially from routine sewage samples collected between 7 and 13 April 2013 in two cities in the Southern district. WPV₁-specific analysis of samples indicated WPV₁ introduction into that area in early February 2013. National supplementary immunisation with oral polio vaccine has been ongoing since August 2013.

142 citations

Journal ArticleDOI
30 Dec 2011-Vaccine
TL;DR: There were real opportunities to achieve new landmarks in polio eradication, especially in the key WPV reservoirs of India and Nigeria, setting the stage for polio to soon follow smallpox into the history books.

127 citations

Journal ArticleDOI
22 Aug 2014-Science
TL;DR: Controversy over vaccine choice for polio eradication can be reconciled by effective combined use of IPV and Sabin together, and IPV in OPV-vaccinated individuals boosts intestinal mucosal immunity.
Abstract: Inactivated poliovirus vaccine (IPV) is efficacious against paralytic disease, but its effect on mucosal immunity is debated. We assessed the efficacy of IPV in boosting mucosal immunity. Participants received IPV, bivalent 1 and 3 oral poliovirus vaccine (bOPV), or no vaccine. A bOPV challenge was administered 4 weeks later, and excretion was assessed 3, 7, and 14 days later. Nine hundred and fifty-four participants completed the study. Any fecal shedding of poliovirus type 1 was 8.8, 9.1, and 13.5% in the IPV group and 14.4, 24.1, and 52.4% in the control group by 6- to 11-month, 5-year, and 10-year groups, respectively (IPV versus control: Fisher's exact test P < 0.001). IPV reduced excretion for poliovirus types 1 and 3 between 38.9 and 74.2% and 52.8 and 75.7%, respectively. Thus, IPV in OPV-vaccinated individuals boosts intestinal mucosal immunity.

106 citations