Detection of human parvovirus 4 DNA in the patients with acute encephalitis syndrome during seasonal outbreaks of the disease in Gorakhpur, India.

Seasonal outbreaks of acute encephalitis syndrome (AES) at Gorakhpur, India have been recognized since 2006. So far, the causative agent has not been identified. Use of next generation sequencing identified human parvovirus 4 (HPARV4) sequences in a CSF/plasma pool. These sequences showed highest identity with sequences earlier identified in similar patients from south India. Real-time PCR detected HPARV4 DNA in 20/78 (25.6%) CSF and 6/31 (19.3%) plasma of AES patients. Phylogenetic analysis classified three almost complete genomes and 24 partial NS1 sequences as genotype 2A. The observed association of HPARV4 with AES needs further evaluation. ELISAs for the detection of IgM and IgG antibodies against scrub typhus (Orientia tsutsugamushi, OT) showed ∼70% IgM/IgG positivity suggestive of etiologic association. Prospective, comprehensive studies are needed to confirm association of these agents, singly or in combination with AES in Gorakhpur region.

Immunogenicity and efficacy of the monovalent, trivalent and quadrivalent intranasal live attenuated influenza vaccines containing different pdmH1N1 strains.

A ferret challenge study was conducted to address the efficacy of the egg-based and Madin-Darby canine kidney (MDCK)-based live attenuated influenza vaccine (LAIV) strains. Vaccines derived as 6:2 reassortants from the A/Leningrad/134/17/57 master donor strain and the HA and NA components from the A/California/07/2009 (A/Cal)- and A/Michigan/45/2015 (A/Mich)-like strains of type A H1N1 influenza virus were used in the study. Monovalent, trivalent and quadrivalent formulations of the LAIV containing either of the two H1N1 strains were analysed. A total of ten groups of six animals each were immunised intranasally (i.n.) with a single dose of 0.5-ml vaccine formulation or placebo and challenged on day 28 with the homologous wild-type A/Cal or A/Mich strain. Immune response post immunisation and virus replication post challenge were studied. Both the strains derived from embryonated eggs or MDCK cells, irrespective of the vaccine valency, were capable of rendering complete protection from virus replication in the lung. The A/Mich vaccine strain showed higher immune titres and efficacy than the A/Cal vaccine strain in all the vaccine formulations. The haemagglutination inhibition and virus neutralisation antibody titres were induced, and the reduction in the virus load in the respiratory tract was observed to be higher in animals treated with the monovalent formulation compared to the trivalent and quadrivalent formulations. Overall, it appears that the monovalent formulations render better protection from infection and would therefore be the best candidate during a pandemic.

Inter-Clade Protection Offered by Mw-Adjuvanted Recombinant HA, NP Proteins, and M2e Peptide Combination Vaccine in Mice Correlates with Cellular Immune Response.

We documented earlier that Mw (heat-killed suspension of Mycobacterium indicus pranii) adjuvant when used with conserved antigens, nucleoprotein (NP), and ectodomain of matrix (M2) protein (M2e) provided complete protection against homologous (clade 2.2) virus challenge in mice. The present study extends these observations to inter-clade challenge (clade 2.3.2.1) H5N1 virus and attempts to understand preliminary immunologic basis for the observed protection. Female BALB/c mice immunized with a single or two doses of vaccine formulations (clade 2.2 antigens) were challenged with 100LD50 homologous or heterologous (clade 2.3.2.1) virus. To understand the preliminary immunologic mechanism, we studied proportions of selected immune cell types, immune response gene expression, and Th1/Th2 cytokines induced by antigen-stimulated splenocytes from immunized mice, at different time points. Complete protection was conferred by Mw-HA, Mw-HA + NP, and Mw-HA + NP + M2e against homologous challenge. The protection correlated with IgG2a antibody titers indicating important role of Th1 response. Despite high inter-cladal antigenic differences, complete protection against the heterologous strain was achieved with Mw-HA + NP + M2e. Of note, a single dose with higher antigen concentrations (50 µg HA + 50 µg NP + 50 µg M2e) led to 80% protection against clade 2.3.2.1 strain. The protection conferred by Mw-HNM correlated with induction of IFN-γ, CD8+ T cytotoxic cells, and CD4+ T helper cells. Mw-adjuvanted HA + NP + M2e combination represents a promising vaccine candidate deserving further evaluation.

Evaluation of Liposome, Heat-Killed Mycobacterium w, and Alum Adjuvants in the Protection Offered by Different Combinations of Recombinant HA, NP proteins, and M2e Against Homologous H5N1 Virus.

Continued evolution of highly pathogenic H5N1 viruses causing high mortality in humans obviates need for broadly cross-reactive vaccines. For this, hemagglutinin (HA) inducing specific protective antibodies, highly conserved nucleoprotein (NP), and ectodomain of matrix (M2e) protein, either singly or in combination, were evaluated in BALB/c mice. Recombinant HA and NP (baculovirus system) and M2e (synthetic peptide) and 3 adjuvants, that is, liposomes, Mw (heat killed Mycobacterium w), and alum were utilized for the homologous virus challenge. Additional immunogens included liposome-encapsulated HA/NP proteins and corresponding DNAs. Mice groups received two doses of respective formulations given at 3-week intervals and challenged intranasally with 100LD50 of H5N1 virus strain. Dynamics of weight loss, lung viral load, titres of IgG-anti-HA, NP, and M2e antibodies (ELISA), and IgG-subtype analysis was done. Two doses of all the formulations led to 100% seroconversion against the immunogens evaluated (100% seroconversion after the first dose in majority). Antibody titres against the components were dependent on the adjuvant and combination. HA-driven Th2 response with all the adjuvants, balanced Th1/Th2 response to NP protein, and Th2-bias with alum were noted. Low anti-M2e antibody titres did not allow subtype analysis. On challenge, complete protection was observed with Mw-HA, alum-HA+NP, Lipo-HA+NP+M2e, alum-HA+NP+M2e, and HA-DP formulations with 12-fold, 8-fold, 720-fold, 17-fold, and no reduction, respectively, in lung viral load. In conclusion, the results identify several adjuvant-immunogen combinations conferring 100% protection in mice that need further evaluation in higher animals.