Emergence of two novel sublineages Ind2001BD1 and Ind2001BD2 of foot-and-mouth disease virus serotype O in Bangladesh

Emergence of a novel sublineage, MYMBD21 under SA-2018 lineage of Foot-and-Mouth Disease Virus serotype O in Bangladesh

Foot-and-Mouth Disease (FMD) hinders the growth of the livestock industry in endemic countries like Bangladesh. The management and prevention of FMD are severely impacted by the high mutation rate and subsequent frequent generation of newer genotypes of the causative agent, Foot-and-Mouth Disease Virus (FMDV). The current study was conducted in nine districts of Bangladesh during 2019-21 to characterize the circulating FMDV strains based on the VP1 sequence analysis, the major antigenic recognition site providing serotype specificity and high variability of FMDV. This study detected the first emergence of the SA-2018 lineage in Bangladesh along with the predominance of Ind-2001e (or Ind-2001BD1) sublineage of ME-SA topotype under serotype O during 2019-21. The mutational spectrum, evolutionary divergence analysis and multidimensional plotting confirmed the isolates collected from Mymensingh districts, designated as MYMBD21 as a novel sublineage under the SA-2018 lineage. Analysis of the amino acid sequence revealed several changes in the G-H loop, B-C loop and C-terminal region of VP1, revealing a 12-13% divergence from the existing vaccine strains and a 95% VP1 protein homology, with most of the mutations potentially considerable as vaccine escape mutations, evidenced by three-dimensional structural analysis. This is the first report on the emergence of the SA-2018 lineage of ME-SA topotype of FMDV serotype O in Bangladesh, as well as a possible mutational trend towards the emergence of a distinct sublineage under SA-2018 lineage, which calls for in-depth genome-wide analysis and monitoring of the FMD situation in the country to implement a strategic vaccination and effective FMD control program.

Detection of an emerging novel sublineage Ind2001BD1 and lineage PanAsia of foot-and-mouth disease virus serotype O in cattle in Manikgonj district of Bangladesh, 2018

Background:

Foot-and-mouth disease (FMD) is an endemic disease of cloven-hoofed animals in Bangladesh and multiple outbreaks occur every year because of the FMD virus (FMDV).

Aim:

The aim of the present investigation was to determine the molecular characterization of the VP1 coding region of FMDV serotype O outbreak in cattle.

Methods:

A total of four tongue epithelial specimens were collected from clinically FMD-positive cattle during June 2018 in Manikgonj district of Bangladesh.

Results:

All four isolates were recorded positive for FMDV serotype O. The phylogenetic analysis showed that two isolates were clustered within an emerging novel sublineage Ind2001BD1 under lineage Ind2001 of FMDV serotype O, which was identified during 2012–2016 in Bangladesh. One isolate was clustered within the lineage PanAsia of FMDV serotype O and was closely related to an isolate identified in Nepal in 2009. The phylogenetic reconstruction revealed that all the four isolates belong to the Middle East–South Asia topotype.

Conclusion:

Therefore, multiple lineages of the FMDV serotype O are circulating among the cattle in the outbreak area, which make it more complex for the FMD control program in Bangladesh. A comprehensive study on the genetic characteristics of FMDV across the country is required for effective FMD prevention and control strategy.

In silico Evolutionary Divergence Analysis Suggests the Potentiality of Capsid Protein VP2 in Serotype-Independent Foot-and-Mouth Disease Virus Detection

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.

Development and serology based efficacy assessment of a trivalent foot-and-mouth disease vaccine

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 < 1 log₁₀ TCID₅₀ in a 10000-liter batch liquid preparation after 24 h inactivation cycle. The inactivated virus particles were significantly (p < 0.05) concentrated and the trivalent vaccine was formulated using 6 µg per dose per serotype antigen payload. The trivalent vaccine was administered in divided doses in different groups of cattle. All doses of the vaccine elicited significantly (p < 0.05) higher levels of antibodies as early as 14-day post-vaccination (dpv) and peak antibody titers were achieved in 28 dpv. The 'full dose' (6.0 µg per dose per serotype) vaccine elicited antibody titers expected to confer protection in 100% cattle of the respective group and maintained such level of antibodies beyond 180 dpv. Thus, the trivalent FMD vaccine prepared with 6.0 µg antigen per dose per serotype of the selected candidate viruses will confer protection against circulating FMDVs of Bangladesh and its neighboring countries.

Evidence of combined effect of amino acid substitutions within G-H and B-C loops of VP1 conferring serological heterogeneity in foot-and-mouth disease virus serotype A

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 VP3^Δ59 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.

Complete genome sequence of a potential foot-and-mouth disease virus serotype O vaccine strain from Bangladesh

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 Space-Time Clusters and Risk Factors in Cattle and Buffalo in Bangladesh

Foot-and-mouth disease (FMD) is highly endemic in Bangladesh. Using passive surveillance data (case records from all 64 districts of Bangladesh, 2014–2017) and district domestic ruminant population estimates, we calculated FMD cumulative incidence per 10,000 animals at risk per district, conducted cluster (Moran’s spatial autocorrelation and scan statistics) and hotspot analysis (local indicator of spatial association statistic), created predictive maps and identified risk factors using a geographically weighted regression model. A total of 548,817 FMD cases in cattle and buffalo were reported during the four-year study period. The highest proportion (31.5%) of cases were reported during the post-monsoon season, and from Chattogram (29.2%) division. Five space-time clusters, 9 local clusters, and 14 hotspots were identified. Overall, higher cumulative incidences of FMD were consistently predicted in eastern parts of Bangladesh. The precipitation in the pre-monsoon season (p = 0.0008) was positively associated with FMD in Bangladesh. Results suggest climate plays an important role in the epidemiology of FMD in Bangladesh, and high risk zones exist. In a resource limited-setting, hotspots and clusters should be prioritized for vaccination coverage, and surveillance for FMD should be targeted in eastern areas of Bangladesh and during the post-monsoon season.

Emergence of novel lineage of foot-and-mouth disease virus serotype Asia1 BD-18 (G-IX) in Bangladesh

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.

First detection of foot-and-mouth disease virus O/ME-SA/ Ind2001e sublineage in Jordan

Foot-and-mouth disease (FMD) is a highly contagious vesicular disease that is caused by the FMD virus (FMDV). This disease affects both wild and domestic cloven-hoofed animals, and the latter of which includes cattle, swine, sheep and goats. FMD is endemic to Jordan and has a severe impact on the productivity of domestic livestock. In January 2017, FMD outbreaks were detected in different animal species across Jordan, resulting in high mortality rates among young lamb and goat populations as well as causing classic FMD symptoms in cattle. In this study, clinical specimens were collected from animals affected by FMD. The results obtained from sequencing the VP1 gene place the studied FMDV isolate within the FMDV O/ME-SA/ Ind2001e sublineage. Phylogenetic analysis of VP1 suggests that the O/JOR/1/2017 isolate is very similar to that of viruses isolated from Saudi Arabia in 2016. The possible introduction of this strain to Jordan might occur through transboundary animal movement or other transmission routes from Saudi Arabia, a neighbouring country.

Near-Complete Genome Sequence of a Potential Foot-and-Mouth Disease Virus Serotype A Vaccine Strain Isolated from Bangladesh

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.

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.

Near-Complete Genome Sequence of a Representative Strain within a Rare Foot-and-Mouth Disease Virus O/ME-SA/Ind2001BD2 Sublineage from Bangladesh

The near-complete genome sequence of a foot-and-mouth disease virus (FMDV), strain O/ME-SA/Ind2001BD2, isolated exclusively from Bangladesh, is reported here. Amino acid substitutions at critical antigenic sites of the capsid were identified compared to the surface proteins of existing vaccine strain O/India/R2/75 and contemporary FMDV serotype O isolates of Bangladesh.

The near-complete genome sequence of a foot-and-mouth disease virus (FMDV), strain O/ME-SA/Ind2001BD2, isolated exclusively from Bangladesh, is reported here. Amino acid substitutions at critical antigenic sites of the capsid were identified compared to the surface proteins of existing vaccine strain O/India/R2/75 and contemporary FMDV serotype O isolates of Bangladesh.

Outbreak investigation, molecular detection, and characterization of foot and mouth disease virus in the Southern part of Bangladesh

Objective:

The objective of the study was to investigate Foot and Mouth Disease virus (FMDV) outbreak in cattle in the Sarankhola Upazila under Bagerhat district of Bangladesh with isolation, identification, and molecular characterization of FMDV during April 2018.

Materials and Methods:

This Upazila is located at southern border of Bangladesh and surrounded by mangrove forest Sundarban. The outbreak investigation team collected epidemiological data from outbreak location. In addition, the team collected a total of 30 (15 calves, 15 adult) tongue epithelial tissue samples from a clinically FMD-affected cattle. The confirmation of FMDV and its three serotypes (A, O, and Asia-1) was performed by Reverse Transcriptase Polymerase Chain Reaction (RT-PCR). An amplified product of the VP1 region of FMDV genome was sequenced by Sanger sequencing method after cultivation and reconfirmation of FMDV into the BHK21 cell line. Genetic variability was studied by constructing a phylogenetic tree.

Results:

The investigation survey was carried out in overall 8,393 (8,393/15,580; 53.89%) cases including 3,050 (3,050/8,393; 36.34%) cases in calf and 5,343 (5,343/8,393; 59.77%) cases in adult cattle. The overall case fatality rate (CFR) was recorded as 2.27% (354/15,580) with significantly highest CFR in the calf (71.46%; 253/354) compared to an adult. The collected all 30 samples found with FMDV positive and mixed infection of all samples with serotype Asia-1 and serotype O were observed. In BHK 21 cell line, the eight FMDV positive samples showed a typical cytopathic effect during the third passage. Finally, DNA sequence data of two isolates found closely related with the isolates of bordering country India and Myanmar.

Conclusion:

The investigation identified the risk factors involved in an outbreak of FMDV, namely, sharing the common paddy land after harvesting, no FMD vaccination, the interaction between cattle and wildlife, and cross bordering movement.

Foot-and-mouth disease virus O/ME-SA/Ind 2001 lineage outbreak in vaccinated Holstein Friesian cattle in Saudi Arabia in 2016

Background: Foot-and-mouth disease virus (FMDV) is a highly contagious viral infection of large ruminants. Despite the massive application of vaccines against FMDV, several outbreaks are still being reported in Africa and Asia.

Aim: To perform molecular characterization of FMDV in an outbreak among a cattle herd Saudi Arabia in 2016. This herd had been vaccinated with a polyvalent FMDV vaccine.

Methods: To investigate this outbreak, we collected specimens from 77 animals showing typical clinical signs of FMDV. Specimens including sera, nasal swabs, and tissues (tongue, coronary bands, hooves, and hearts) were collected. We tested the collected cattle sera for the presence of FMDV antibodies with commercial ELISA kits. In addition, we tested the swabs for the presence of the most common FMDV strains (O, A, Asia-1 and SAT-2) with RT-PCR using serotype-specific oligonucleotides.

Results: Serology showed that 22% of the tested sera were positive. Molecular testing of the examined swabs confirmed that 24% of the tested animals were positive. Our sequencing analysis confirmed that the circulating strains of FMDV belonged to FMDV serotype O. The phylogenetic tree based on the FMDV-VP-1 gene revealed high nucleotide identity between the circulating strains and the Bangladesh strain (99%). These strains were distinct (shared 89% nucleotide identity) from the FMDV-O strains used for the preparation of the vaccine administered to the animals in this herd. Moreover, they had 7% nucleotide difference between the FMDV-O strains reported in Saudi Arabian in 2013.

Conclusion: More in-depth molecular characterization of these FMDV strains is warranted.

First detection of foot-and-mouth disease virus O/ME-SA/Ind2001 in China

Foot-and-mouth disease (FMD) is endemic in China and is predominantly due to foot-and-mouth disease virus (FMDV) serotype O Mya-98 lineage. In recent years, FMDV O/ME-SA/Ind2001 lineage has spread from the Indian subcontinent to South-East Asia, Middle East and Africa, which may pose potential threats for future trans-regional livestock movements. In this study, we identified the appearance of FMDV O/ME-SA/Ind2001 in China; the first time that this virus lineage has been found there. Sequencing and phylogenetic analysis of VP1 sequences revealed that this newly determined strain belongs to O/ME-SA/Ind2001 sublineage d and is closely related to strains that have caused recent outbreaks of FMD in Nepal, Myanmar, Russia and South Korea. The results suggest extensive movements of the current O/ME-SA/Ind2001 sublineage d viruses and provide essential information for an effective national FMDV control programme in China.