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Foot-and-mouth disease virus (FMDV) serotype A exhibits a higher degree of genetic and antigenic diversity resulting in frequent vaccine failure due to serological mismatch between the vaccine and heterologous strains. Currently, knowledge on the molecular basis of antigenic relationships among the FMDVs is limited; nevertheless, intratype antigenic variation due to mutation(s) is widely considered as the main hurdle to appropriate FMD vaccine development. Here, we studied genetic and antigenic variations of four FMDV serotype A isolates, BAN/GA/Sa-197/2013 (BAN-197), BAN/CH/Sa-304/2016 (BAN-304), BAN/DH/Sa-307/2016 (BAN-307) and BAN/DH/Sa-310/2017 (BAN-310) circulating in Bangladesh during 2013-2017. Initially, antigenic relationships (r1 -values) of the field isolates were evaluated by the two-dimensional microneutralization test (2D-MNT) using the hyperimmune antisera raised in cattle against the vaccine strain, BAN-304. Interesingly, the results showed protective serological cross-reactivity (r1 -values > 0.4) between the vaccine strain and the field isolates, BAN-307 and BAN-310, except BAN-197 that substantially mismatched (r1 = 0.129 ± 0.043) with the BAN-304. Although VP1-based phylogeny grouped all the isolates within the same sublineage C (a subgroup of VP3Δ59 variant) under the lineage A/ASIA/G-VII, strikingly, computational analyses of the viral capsid proteins demonstrated significant deviation at the VP1 G-H loop of BAN-197 from the vaccine strain, while VP(2-4) of both isolates were structurally conserved. To bridge the gap of how the distortion of the G-H loop and consequent antigenic hetergeneity occurred in BAN-197, we performed in silico combinatorial substitutions of the VP1 mutant amino acids (aa) of BAN-197 with the respective residues in BAN-304. Remarkably, our analyses revealed that two substitutions of distantly located aa at B-C (T48I:threonine → isoleucine) and G-H (A143V:alanine → valine) loops, in combination, distorted the VP1 G-H loop. Overall, this work contributes to understanding the molecular basis of antigenic relationships operating in serotype A FMDVs and the selection of suitable vaccine strain(s) for effective prophylaxis of FMD based on VP1-based analyses.

One of the six sublineages of the dominant O/ME-SA/Ind2001 lineage of foot-and-mouth disease virus (FMDV), Ind2001BD1 has already spread throughout 14 countries, including Bangladesh. Here, we report the complete genome sequence of the potential serotype O vaccine strain BAN/TA/Dh-301/2016, which has been shown to provide protection against all the circulating serotype O viruses in Bangladesh. The viral genome is 8,211 nucleotide (nt) long with an open reading frame (ORF) of 6999 nt. The ORF is flanked by a 1098-nt-long 5'-UTR and a 114-nt-long 3'-UTR. Compared to the Indian FMDV serotype O vaccine strain O/India/R2/75 (AF204276), ten mutations were identified in the major antigenic sites of BAN/TA/Dh-301/2016 (MK088170.1).

Foot-and-mouth disease virus (FMDV) is a highly evolutionary divergent pathogen causing great economic havoc in many countries. Among its seven existing serotypes, Asia1 is the least divergent with a single topotype both genetically and antigenically. It is reported sporadically in Indian subcontinent and was classified under lineage G-VIII. In 2018, serotype Asia1 re-emerged in Bangladesh after 2013, along with circulation of a novel serotype Asia1 BD-18 (G-IX) lineage. VP1 phylogeny and sequence variation clearly demonstrated the novel strains which was estimated to have at least >5% nucleotide divergence with distinct clade formation. Also, the Bayesian phylogeographic inferences traced back to the origin time of lineage G-IX in early 2017 and a possible origin in Bangladesh. Mutational analysis considering established eight lineages revealed that the virus strains belonged to lineage G-IX contained a unique mutation at 44 position in the B-C loop region of VP1. Inappropriate vaccination and inefficient outbreak surveillance possibly contributed to the current episode of emergence. Therefore, active surveillance and continued vigilance are essential to assess and timely detect the occurrence, extent and distribution of this novel Asia1 strains in Bangladesh and the neighbouring countries.

Global emergence and dissemination of carbapenemases are clinically threatening, notably in countries with endemic blaNDM. To analyze the extent of carbapenemases in Bangladesh, 71 isolates were collected from 7 different clinical sources: wound swab (n = 38), pus (n = 13), urine (n = 9), blood (n = 4), tracheal aspirate (n = 3), pleural fluid (n = 1) and vaginal swab (n = 3) from Dhaka Medical College Hospital, Bangladesh. Among the isolates, 25 were resistant to at least one of the three carbapenems (imipenem, meropenem and doripenem), including 15 being resistant to all. These resistant isolates were identified as Pseudomonas aeruginosa, Acinetobacter baumannii, Klebsiella pneumoniae, P. hibiscicola, Proteus mirabilis, Providencia stuartii and Citrobacter sedlakii. Carbapenemase detection among these 25 isolates varied in individual phenotypic assays (83% in Modified Hodge Test, 50% in Combined Disk Test for Metallo-β-lactamase prediction) as compared with the genotypes observed (96% prevalence of various carbapenemases including blaOXA-1,48, blaNDM-1,5, blaVIM-2,5). blaOXA-48 was the most prevalent gene (84%) followed by blaNDM (72%). Coexistence of multiple gene combination such as blaNDM+blaOXA-48+blaOXA-1 was prevalent (48%). Harborage of blaVIM-5 (n = 1) was characterized for the first time, while blaNDM-5 (n = 5) was reported contemporarily with a recent study in Bangladesh. Presence of plasmids (64%) and integron class 1 (100%) signifies the transferable potential of resistant traits. The emergence of such new variants along with the presence of the mobile genetic elements demands strict surveillance and combating strategies.

The emerged novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has created a global health crisis that warrants an accurate and detailed characterization of the rapidly evolving viral genome for understanding its epidemiology, pathogenesis, and containment. Here, we explored 61,485 sequences of the nucleocapsid (N) protein, a potent diagnostic and prophylactic target, for identifying the mutations to review their roles in real-time polymerase chain reaction based diagnosis and observe consequent impacts. Compared to the Wuhan reference strain, a total of 1034 unique nucleotide mutations were identified in the mutant strains (49.15%, n = 30,221) globally. Of these mutations, 367 occupy primer binding sites including the 3'-end mismatch to the primer-pair of 11 well-characterized primer sets. Noteworthily, CDC (USA) recommended the N2 primer set contained a lower mismatch than the other primer sets. Moreover, 684 amino acid (aa) substitutions were located across 317 (75.66% of total aa) unique positions including 82, 21, and 83 of those in the RNA binding N-terminal domain (NTD), SR-rich region, and C-terminal dimerization domain, respectively. Moreover, 11 in-frame deletions, mostly (n = 10) within the highly flexible linker region, were revealed, and the rest was within the NTD region. Furthermore, we predicted the possible consequence of high-frequency mutations (≥20) and deletions on the tertiary structure of the N protein. Remarkably, we observed that a high frequency (67.94% of mutated sequences) co-occuring mutations (R203K and G204R) destabilized and decreased overall structural flexibility. The N protein of SARS-CoV-2 comprises an average of 1.2 mutations per strain compared to 4.4 and 0.4 in Middle East respiratory syndrome-related coronavirus and SARS-CoV, respectively. Despite being proposed as the alternative target to spike protein for vaccine and therapeutics, the ongoing evolution of the N protein may challenge these endeavors, thus needing further immunoinformatics analyses. Therefore, continuous monitoring is required for tracing the ongoing evolution of the SARS-CoV-2 N protein in prophylactic and diagnostic interventions.

Foot-and-mouth disease (FMD) is an economically devastating disease of the livestock worldwide and caused by the FMD virus (FMDV), which has seven immunologically distinct serotypes (O, A, Asia1, C, and SAT1–SAT3). Studies suggest that VP2 is relatively conserved among three surface-exposed capsid proteins (VP1–VP3) of FMDV, but the level of conservation has not yet been reported. Here we analyzed the comparative evolutionary divergence of VP2 and VP1 to determine the level of conservation in VP2 at different hierarchical levels of three FMDV serotypes (O, A, and Asia1) currently circulating in Asia through an in-depth computational analysis of 14 compiled datasets and designed a consensus VP2 protein that can be used for the development of a serotype-independent FMDV detection tool. The phylogenetic analysis clearly represented a significant level of conservation in VP2 over VP1 at each subgroup level. The protein variability analysis and mutational study showed the presence of 67.4% invariant amino acids in VP2, with the N-terminal end being highly conserved. Nine inter-serotypically conserved fragments located on VP2 have been identified, among which four sites showed promising antigenicity value and surface exposure. The designed 130 amino acid long consensus VP2 protein possessed six surface-exposed B cell epitopes, which suggests the possible potentiality of the protein for the development of a serotype-independent FMDV detection tool in Asia. Conclusively, this is the first study to report the comparative evolutionary divergence between VP2 and VP1, along with proposing the possible potentiality of a designed protein candidate in serotype-independent FMDV detection.

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), a novel evolutionary divergent RNA virus, is responsible for the present devastating COVID-19 pandemic. To explore the genomic signatures, we comprehensively analyzed 2,492 complete and/or near-complete genome sequences of SARS-CoV-2 strains reported from across the globe to the GISAID database up to 30 March 2020. Genome-wide annotations revealed 1,516 nucleotide-level variations at different positions throughout the entire genome of SARS-CoV-2. Moreover, nucleotide (nt) deletion analysis found twelve deletion sites throughout the genome other than previously reported deletions at coding sequence of the ORF8 (open reading frame), spike, and ORF7a proteins, specifically in polyprotein ORF1ab (n = 9), ORF10 (n = 1), and 3´-UTR (n = 2). Evidence from the systematic gene-level mutational and protein profile analyses revealed a large number of amino acid (aa) substitutions (n = 744), demonstrating the viral proteins heterogeneous. Notably, residues of receptor-binding domain (RBD) showing crucial interactions with angiotensin-converting enzyme 2 (ACE2) and cross-reacting neutralizing antibody were found to be conserved among the analyzed virus strains, except for replacement of lysine with arginine at 378th position of the cryptic epitope of a Shanghai isolate, hCoV-19/Shanghai/SH0007/2020 (EPI_ISL_416320). Furthermore, our results of the preliminary epidemiological data on SARS-CoV-2 infections revealed that frequency of aa mutations were relatively higher in the SARS-CoV-2 genome sequences of Europe (43.07%) followed by Asia (38.09%), and North America (29.64%) while case fatality rates remained higher in the European temperate countries, such as Italy, Spain, Netherlands, France, England and Belgium. Thus, the present method of genome annotation employed at this early pandemic stage could be a promising tool for monitoring and tracking the continuously evolving pandemic situation, the associated genetic variants, and their implications for the development of effective control and prophylaxis strategies.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the ongoing pandemic of coronavirus disease 2019 (COVID-19), a public health emergency of international concern declared by the World Health Organization (WHO). An immuno-informatics approach along with comparative genomic was applied to design a multi-epitope-based peptide vaccine against SARS-CoV-2 combining the antigenic epitopes of the S, M and E proteins. The tertiary structure was predicted, refined and validated using advanced bioinformatics tools. The candidate vaccine showed an average of ≥ 90.0% world population coverage for different ethnic groups. Molecular docking of the chimeric vaccine peptide with the immune receptors (TLR3 and TLR4) predicted efficient binding. Immune simulation predicted significant primary immune response with increased IgM and secondary immune response with high levels of both IgG1 and IgG2. It also increased the proliferation of T-helper cells and cytotoxic T-cells along with the increased INF-γ and IL-2 cytokines. The codon optimization and mRNA secondary structure prediction revealed the chimera is suitable for high-level expression and cloning. Overall, the constructed recombinant chimeric vaccine candidate demonstrated significant potential and can be considered for clinical validation to fight against this global threat, COVID-19.

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals throughout the world. The endemicity of this disease in Bangladesh has been causing high economic loss and an impediment to the full potential surge of livestock industries. In Bangladesh, vaccination using imported or locally produced FMD vaccines is the existing practice of controlling the disease, although vaccine failure cases are very common. Hence, to address the problem, the present study was envisaged to develop an effective FMD vaccine tailored to the circulating indigenous foot-and-mouth disease virus (FMDV) strains. Three local circulating FMDVs O/BAN/TA/Dh-301/2016 ( MK088170.1 ), A/BAN/CH/Sa-304/2016 ( MK088171.1 ) and Asia1/BAN/DH/Sa-318/2018 ( MH457186.1 ) isolates were selected as vaccine strains based on recent epidemiology, genetic and antigenic analyses. These serotype O, A and Asia1 vaccine strains showed strong antigenic relationship (r1 > 0.3) with 100% to 75% of the respective circulating viruses. The candidate viruses were successfully inactivated by 3.0 mM binary ethylenimine within 7–10 h after the onset of inactivation. Extrapolation of inactivation kinetics confirmed

White Spot Syndrome Virus (WSSV), the etiological agent of White Spot Disease (WSD) is a major impediment for shrimp aquaculture in the worldwide. A critical threshold level of WSSV load in infected shrimp is an important trait for disease manifestation and WSSV transmission in cultured shrimp and subsequently make outbreaks. The present study investigated 120 naturally infected cultured shrimp samples by SYBR Green based qPCR assay for WSD diagnosis and quantification of WSSV load. Among them, 94 samples resulted a variable count of WSSV load ranging from 2.1 × 108 to 2.64 × 1014 copies/g of shrimp tissue. The severity of WSSV infection was assessed based on the established critical threshold load of WSSV in shrimp tissue. Compared to the established critical threshold value of WSSV load in shrimp tissue, our findings showed the horrifying scenario of the severity of WSSV infection in cultured shrimps of Bangladesh that was found to be above the critical limit to initiate an outbreak in the Bangladeshi shrimp aquaculture industry. The latest phylogenetic pattern was altered from the former monophyletic history among WSSVs of Bangladesh due to a variation at 500th nucleotide of VP28 coding gene. Viruses characterized from recent outbreaks in 2015 and 2017 displayed amino acid substitution at position 167 (G→E) on the surface of VP28 protein which has demonstrated the probable replacement of indigenous virus pool. Therefore, it is imperative to take initiative for the management and prevention of WSSV outbreak to sustain shrimp aquaculture in South-West region of Bangladesh. Electronic supplementary material The online version of this article (10.1186/s13568-018-0553-z) contains supplementary material, which is available to authorized users.

The near-complete genome sequence of foot-and-mouth disease virus (FMDV) serotype A potential vaccine strain BAN/CH/Sa-304/2016 is reported here. Its genome revealed antigenic heterogeneity with the current Indian vaccine strain IND40/00, with four amino acid substitutions in antigenically critical sites of the VP1 protein.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiologic agent of the ongoing pandemic of coronavirus disease 2019 (COVID-19), a public health emergency of international concerns declared by the World Health Organization (WHO). An immuno-informatics approach along with comparative genomics was applied to design a multi-epitope-based peptide vaccine against SARS-CoV-2 combining the antigenic epitopes of the S, M, and E proteins. The tertiary structure was predicted, refined and validated using advanced bioinformatics tools. The candidate vaccine showed an average of ≥90.0% world population coverage for different ethnic groups. Molecular docking and dynamics simulation of the chimeric vaccine with the immune receptors (TLR3 and TLR4) predicted efficient binding. Immune simulation predicted significant primary immune response with increased IgM and secondary immune response with high levels of both IgG1 and IgG2. It also increased the proliferation of T-helper cells and cytotoxic T-cells along with the increased IFN-γ and IL-2 cytokines. The codon optimization and mRNA secondary structure prediction revealed that the chimera is suitable for high-level expression and cloning. Overall, the constructed recombinant chimeric vaccine candidate demonstrated significant potential and can be considered for clinical validation to fight against this global threat, COVID-19.

‘Tubifex worms’ encompass extensive cryptic diversity that requires molecular characterization to confirm the species commonly found in Bangladesh including their lineages. Therefore, this study focused on the molecular characterization and phylogeny analysis at lineages level by sequencing the fragment of 16S rRNA and cytochrome c oxidase subunit I (COI) genes through standard cloning and sequencing techniques followed by phylogenetic characterization. All six isolates, belong to the genus Limnodrilus that is confirmed into two different species (L. hoffmeisteri and L. claparedianus-cervix) of the tubifex. The phylogenetic analysis estimated that the resident worms are under the same clade although transmissions from other countries might likely occur through different aquatic routes and birds. The drawbacks were the use of a complex colony rather than a single worm and taking representative isolates instead of all the positive amplicons for sequencing. However, this study is the first report of genetical confirmation of the genus Limnodrilus at lineage level from Bangladesh. Keywords: Tubifex, Phylogeny, Cytochrome oxidase, 16S rRNA, Bangladesh

The complete genome sequence of foot-and-mouth disease virus (FMDV) serotype Asia1 isolated from Bangladesh is reported here. Genome analysis revealed amino acid substitutions in the VP1 antigenic region and deletions in both the 5′ and 3′ untranslated regions (UTRs) compared to the genome of the existing vaccine strain (GenBank accession no. AY304994).