Genomic characterization of coxsackievirus type B3 strains associated with acute flaccid paralysis in south-western India.

Acute flaccid paralysis (AFP) associated with coxsackievirus type B3 (CV-B3) of the species Enterovirus B is an emerging concern worldwide. Although CV-B3-associated AFP in India has been demonstrated previously, the genomic characterization of these strains is unreported. Here, CV-B3 strains detected on the basis of the partial VP1 gene in 10 AFP cases and five asymptomatic contacts identified from different regions of south-western India during 2009-2010 through the Polio Surveillance Project were considered for complete genome sequencing and characterization. Phylogenetic analysis of complete VP1 gene sequences of global CV-B3 strains classified Indian CV-B3 strains into genogroup GVI, along with strains from Uzbekistan and Bangladesh, and into a new genogroup, GVII. Genomic divergence between genogroups of the study strains was 14.4 % with significantly lower divergence (1.8 %) within GVI (n = 12) than that within GVII (8.5 %) (n = 3). The strains from both AFP cases and asymptomatic contacts, identified mainly in coastal Karnataka and Kerala, belonged to the dominant genogroup GVI, while the GVII strains were recovered from AFP cases in north interior Karnataka. All study strains carried inter-genotypic recombination with the structural region similar to reference CV-B3 strains, and 5' non-coding regions and non-structural regions closer to other enterovirus B types. Domain II structures of 5' non-coding regions, described to modulate virus replication, were predicted to have varied structural folds in the two genogroups and were attributed to differing recombination patterns. The results indicate two distinct genomic compositions of CV-B3 strains circulating in India and suggest the need for concurrent analysis of viral and host factors to further understand the varied manifestations of their infections.

Genomic characterization of coxsackievirus type A24 strains associated with acute flaccid paralysis and rarely identified Hopkins syndrome.

The full-length genome sequence analysis of four coxsackievirus A24 (CV-A24) strains, detected in three paralytic and one post-asthmatic paralytic (Hopkins syndrome) cases, is reported here for the first time. A phylogenetic tree constructed on the basis of entire genomes displayed topology similar to that of the full-VP1 tree, classifying the study strains in genogroup CV-A24vGIV along with their temporal counterparts in strains from non-paralytic cases. The strains of the study formed a single genetic cluster C4 within CV-A24vGIV and showed 3.5-19.4 % nucleotide sequence divergence, with 2-4 novel nucleotide mutations in the 5'NCR and 3-8 unique amino acid substitutions in the polyprotein, with respect to the CV-A24 strains associated with non-paralytic cases. Among the nucleotide mutations, A299U was identified in the 5'NCRs of all of the study strains. CV-A24v strains of the same genogroup with few genomic variations but different disease manifestations need to be explored to investigate the molecular basis of evolution of neurovirulence.

Characterization of the non-polio enterovirus infections associated with acute flaccid paralysis in South-Western India.

Non-polio enteroviruses (NPEVs) have been reported frequently in association with acute flaccid paralysis (AFP) cases during Polio Surveillance Programs (PSPs) worldwide. However, there is limited understanding on the attributes of their infections. This study reports characteristics of NPEVs isolated from AFP cases, investigated during PSPs held in 2009-2010, in Karnataka and Kerala states of south-western India having varied climatic conditions. NPEV cell culture isolates derived from stool specimens that were collected from 422 of 2186 AFP cases (<1-14 years age) and 17 of 41 asymptomatic contacts; and details of all AFP cases/contacts were obtained from National Polio Laboratory, Bangalore. The distribution of NPEV infections among AFP cases and circulation pattern of NPEV strains were determined by statistical analysis of the data. Genotyping of all NPEV isolates was carried out by partial VP1 gene sequencing and phylogenetic analysis. NPEV positive AFP cases were significantly higher in children aged <2 years; with residual paralysis; in summer months; and in regions with relatively hot climate. Genotyping of NPEVs identified predominance of human enteroviruses (HEV)-B species [81.9%-Echoviruses (E): 57.3%; coxsackieviruses (CV) B: 15%; numbered EVs: 8.9%; CVA9: 0.7%] and low levels of HEV-A [14.5%-CVA: 6%; numbered EVs: 8.5%] and HEV-C [3.6%-CVA: 2.6%; numbered EVs: 1%] species, encompassing 63 genotypes. EV76 (6.3%) and each of E3, CVB3 and E9 (4.97%) were found frequently during 2009 while E11 (6.7%), CVB1 (6.1%), E7 (5.1%) and E20 (5.1%) were detected commonly in 2010. A marked proportion of AFP cases from children aged <2 years; presenting with fever; and from north and south interior parts of Karnataka state was detected with E/numbered EVs than that found with CVA/CVB. This study highlights the extensive genetic diversity and diverse circulation patterns of NPEV strains in AFP cases from different populations and climatic conditions.

Antigenic diversity of enteroviruses associated with nonpolio acute flaccid paralysis, India, 2007-2009.

Because of the broadened acute flacid paralysis (AFP) definition and enhanced surveillance, many nonpolio AFP (NP-AFP) cases have been reported in India since 2005. To determine the spectrum of nonpolio enterovirus (NPEV) serotypes associated with NP-AFP from polio-endemic and -free regions, we studied antigenic diversity of AFP-associated NPEVs. Of fecal specimens from 2,786 children with NP-AFP in 1 polio-endemic and 2 polio-free states, 823 (29.5%) were positive for NPEVs in RD cells, of which 532 (64.6%) were positive by viral protein 1 reverse transcription PCR. We identified 66 serotypes among 581 isolates, with enterovirus 71 most frequently (8.43%) detected, followed by enterovirus 13 (7.1%) and coxsackievirus B5 (5.0%). Most strains within a serotype represented new genogropups or subgenogroups. Agents for ≈35.0% and 70.0% of culture-positive and -negative cases, respectively, need to be identified. Association of human enterovirus with NP-AFP requires better assessment and understanding of health risks of NPEV infections after polio elimination.

Diagnosis of Kyasanur forest disease by nested RT-PCR, real-time RT-PCR and IgM capture ELISA.

Kyasanur forest disease (KFD) is a zoonotic viral disease caused by infection by a Flavivirus, a member of the family Flaviviridae. KFD is a public health concern in the Karnataka State in southern India. Available conventional diagnostic tests such as virus isolation and serological tests, such as haemagglutination inhibition and complement fixation tests are time consuming. This study reports the development of a nested RT-PCR [nRT-PCR] and a TaqMan-based real-time RT-PCR and IgM antibodies capture ELISA [MAC-ELISA] for rapid and accurate diagnosis of suspected KFD cases. The nRT-PCR and the TaqMan-based real-time RT-PCR assays were developed using gene sequences of the NS-5/non-coding region. Both the assays detected KFD viral RNA in acute phase human serum samples and can provide early diagnosis of infection. Real-time RT-PCR was found to be more sensitive than nRT-PCR, which could detect 38 copies of KFDV RNA. MAC-ELISA was developed for the detection of recent infections. Although real-time RT-PCR and nRT-PCR require expensive reagents, expensive equipment and trained personnel, the developed MAC-ELISA can be used easily in the affected areas. These tests add to the existing diagnosis arsenal against haemorrhagic viruses that are prevalent in India. These assays will also help to extend our knowledge of the pathology of KFD virus and its associated clinical features, by measuring the viral titre during infection and at the time of seroconversion. Information, which is not available currently because of the lack of appropriate diagnostic methods. In addition, early laboratory diagnosis of KFDV infection will help in the application of appropriate control measures and management of KFD cases.

Molecular epidemiology of measles in India, 2005-2010.

Measles is a childhood disease that causes great morbidity and mortality in India and worldwide. Because measles surveillance in India is in its infancy, there is a paucity of countrywide data on circulating Measles virus genotypes. This study was conducted in 21 of 28 States and 2 of 7 Union Territories of India by MeaslesNetIndia, a national network of 27 centers and sentinel practitioners. MeaslesNetIndia investigated 52 measles outbreaks in geographically representative areas from 2005 through June 2010. All outbreaks were serologically confirmed by detection of antimeasles virus immunoglobulin M (IgM) antibodies in serum or oral fluid samples. Molecular studies, using World Health Organization (WHO)-recommended protocols obtained 203 N-gene, 40 H-gene, and 4 M-gene sequences during this period. Measles genotypes D4, D7, and D8 were found to be circulating in various parts of India during the study period. Further phylogenetic analysis revealed 4 lineages of Indian D8 genotypes: D8a, D8b, D8c, and D8d. This study generated a large, countrywide sequence database that can form the baseline for future molecular studies on measles virus transmission pathways in India. This study has created support and capabilities for countrywide measles molecular surveillance that must be carried forward.

Evolution, dispersal and replacement of American genotype dengue type 2 viruses in India (1956-2005): selection pressure and molecular clock analyses.

This study reports the phylogeny, selection pressure, genotype replacement and molecular clock analyses of many previously unstudied dengue type 2 virus (DENV-2) strains, isolated in India over a time span of almost 50 years (1956-2005). Analysis of complete envelope (E) gene sequences of 37 strains of DENV-2 from India, together with globally representative strains, revealed that the American genotype, which circulated predominantly in India during the pre-1971 period, was then replaced by the Cosmopolitan genotype. Two previously unreported amino acid residues, one in the American (402I) and one in the Cosmopolitan (126K) genotypes, known to be involved functionally in the cellular tropism of the virus, were shown to be under positive selection pressure. The rate of nucleotide substitution estimated for DENV-2 was 6.5x10(-4) substitutions per site year(-1), which is comparable with earlier estimates. The time to the most recent common ancestor of the pre-1971 Indian strains and the American genotype was estimated to be between 73 and 100 years (1905-1932), which correlates with the historical record of traffic between India and South America and suggests transportation of the virus from the Americas. Post-1971 Indian isolates formed a separate subclade within the Cosmopolitan genotype. The estimated time to the most recent common ancestor of the Indian Cosmopolitan strains was about 47 years, with further estimates indicating the migration of DENV-2 from India to countries across the Indian ocean between 1955 and 1966. Overall, the present study increases our understanding of the events leading to the establishment and dispersal of the two genotypes in India.

Recent ancestry of Kyasanur Forest disease virus.

Kyasanur Forest disease virus (KFDV) is enzootic to India and maintained in ticks, mammals, and birds. It causes severe febrile illness in humans and was first recognized in 1957 associated with a high number of deaths among monkeys in Kyasanur Forest. Genetic analysis of 48 viruses isolated in India during 1957-2006 showed low diversity (1.2%). Bayesian coalescence analysis of these sequences and those of KFDVs from Saudi Arabia and the People's Republic of China estimated that KFDVs have evolved at a mean rate of approximately 6.4 x 10(-4) substitutions/site/year, which is similar to rates estimated for mosquito-borne flaviviruses. KFDVs were estimated to have shared a common ancestor in approximately 1942, fifteen years before identification of the disease in India. These data are consistent with the view that KFD represented a newly emerged disease when first recognized. Recent common ancestry of KFDVs from India and Saudi Arabia, despite their large geographic separation, indicates long-range movement of virus, possibly by birds.

Genetic characterization of Bagaza virus (BAGV) isolated in India and evidence of anti-BAGV antibodies in sera collected from encephalitis patients.

During investigations into the outbreak of encephalitis in 1996 in the Kerala state in India, an arbovirus was isolated from a Culex tritaeniorhynchus mosquito pool. It was characterized as a Japanese encephalitis and West Nile virus cross-reactive arbovirus by complement fixation test. A plaque reduction-neutralization test was performed using hyperimmune sera raised against the plaque-purified arbovirus isolate. The sera did not show reactivity with Japanese encephalitis virus and were weakly reactive with West Nile virus. Complete open reading frame sequence analysis characterized the arbovirus as Bagaza virus (BAGV), with 94.80 % nucleotide identity with African BAGV strain DakAr B209. Sera collected from the encephalitic patients during the acute phase of illness showed 15 % (8/53) positivity for anti-BAGV neutralizing antibodies. This is the first report of the isolation of BAGV from India. The presence of anti-BAGV neutralizing antibodies suggests that the human population has been exposed to BAGV.

Chikungunya outbreaks caused by African genotype, India.

Chikungunya fever is reported in India after 32 years. Immunoglobulin M antibodies and virus isolation confirmed the cause. Phylogenic analysis based on partial sequences of NS4 and E1 genes showed that all earlier isolates (1963-1973) were Asian genotype, whereas the current and Yawat (2000) isolates were African genotype.