Browsing by Author "Esona, M.D."

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Changing patterns of rotavirus genotypes in Ghana: Emergence of human rotavirus G9 as a major cause of diarrhea in children.
(2003) Armah, G.E.; Steele, A.D.; Binka, F.N.; Esona, M.D.; Asmah, R.H.; Anto, F; Brown, D.; Cutts, F.; Green, J.; Hall, A.
Genotyping of human rotaviruses was performed on 312 rotavirus-positive samples collected from 2,205 young children with diarrhea in the Upper East District of Ghana, a rural community. Of the 271 (86.9%) rotavirus strains that could be VP7 (G) or VP4 (P) characterized, 73 (26.9%) were of G9 specificity. The predominant G9 genotype was G9P[8], which constituted 79.5% of all G9 strains detected, followed by G9P[6] (12.3%), G9P[10] (2.7%), and G9P[4] (1.3%). G9 strains with mixed P types constituted 2.7% of all G9 strains found in the study. All the G9P[8] strains had a long RNA electrophoretic pattern with VP6 subgroup II specificity. Four G9 isolates, GH1319, GH1416, GH3550, and GH3574, which were selected based on the abundance of stool material and were representative of the three electropherotypes observed, were cloned and sequenced. The Ghanaian isolates shared more than 98% sequence nucleotide homology with other G9 strains from the United States (US1205), Malawi (MW69), Brazil (R160), Japan (95H115), and Nigeria (Bulumkutu). However, they showed only 95% nucleotide homology with the Thai G9 strain Mc345. Phylogenetic analysis of the nucleic acid sequence revealed the existence of at least three clusters, with Ghanaian strains forming one cluster, Nigerian and Brazilian strains forming a second cluster, and U.S., Malawian, and Japanese strains forming a third.
Characterization of 2 Human Genotype G10 Rotavirus Strains, 3008CM and 1784/CI/1999, Isolated in Cameroon and Cote d’Ivoire during the 1999–2000 Rotavirus Season
(The Journal of Infectious Diseases, 2010) Esona, M.D.; Page, N.A.; Akran, V.A.; Armah, G.E.; Steele, A.D.
During routine rotavirus surveillance projects in Cameroon and Cote d’Ivoire, 2 fecal samples collected from 2 children!5 years of age who presented with symptoms of gastroenteritis were found to give anomalous G typing results. These specimens were strongly rotavirus positive by enzyme immunoassay, displayed VP6 subgroup II specificity and long RNA electropherotypes, and were typed as rotavirus serotype G2 with monoclonal antibodies. In addition, the strains were typed as rotavirus VP7 genotype G3 and VP4 genotype P[8] by reverse-transcription polymerase chain reaction. Further investigation of the polymerase chain reaction Gtyping results with a second set of primers revealed that the specimens were not genotype G3, and both samples were sequenced to elucidate the problem. Both strains were found to be genotype G10 by nucleotide sequence. Comparison of nucleotide and amino acid sequences and phylogenetic analysis of the African G10 strains revealed that these strains are closely related to the human G10 strains that were detected during the 2001–2003 rotavirus season in Ghana. The detection of G10 rotavirus in Africa adds to the global distribution of this strain and strengthens the need to continue strain surveillance in developing countries to understand the extent of strain distribution and diversity.
Comparison of Premier™ Rotaclone®, ProSpecT™, and RIDASCREEN® rotavirus enzyme immunoassay kits for detection of rotavirus antigen in stool specimens
(Journal of Clinical Virology, 2013-07) Gautam, R.; Lyde, F.; Esona, M.D.; Quaye, O.; Bowena, M.D.
Background: Rotaviruses are the major cause of severe dehydrating diarrhea in children throughout the world. Enzyme immunoassays (EIAs) have been the standard method for detection of rotavirus in stool specimens since the 1980s. The World Health Organization (WHO) Rotavirus Surveillance Network has proposed including three EIA kits in the WHO-GSM (Global Management System/Système Mondial de Gestion) catalog for easy procurement of EIA kits by participating rotavirus surveillance network laboratories. Objectives: In this study, we conducted a comparative analysis of 3 commercially available enzyme immunoassay kits: Premier™ Rotaclone® (Meridian Bioscience, Inc.), ProSpecT™ (Oxoid, Ltd.) and RIDASCREEN® (R-biopharm AG) for rotavirus diagnostics. Study design: Using reverse-transcriptase-PCR (RT-PCR) as the gold standard, the 3 EIA kits were evaluated by testing a stool panel consisting of 56 rotavirus-positive and 54 rotavirus negative samples. Results: The sensitivities of the Premier™ Rotaclone®, ProSpecT™ and RIDASCREEN® kits were 76.8%, 75% and 82.1%, respectively, but did not differ significantly. The specificity of all the 3 kits was 100%. The use of RT-PCR as a gold standard lowered the observed sensitivity of all 3 EIA kits but helps to reduce equivocal results that can be seen when another EIA or other non-molecular methods are used as the reference assay in comparison studies. Conclusion: Our study found that all three kits are suitable for use by rotavirus surveillance programs. © 2013 .
Detection of an Unusual Human Rotavirus Strain with G5P[8] Specificity in a Cameroonian Child with Diarrhea
(Journal of Clinical Microbiology, 2004-01) Esona, M.D.; Armah, G.E.; Geyer, A.; Steele, A.D.
Rotavirus strains detected as part of ongoing strain surveillance in Cameroon, and whose first-round reverse transcription-PCR product could not be genotyped by using conventional genotyping primers, were subjected to sequence analysis for strain characterization. We detected for the first time in Africa a human rotavirus with G5 specificity. The Cameroonian G5 strain had a short electrophoretic pattern and was of VP6 subgroup I specificity and a VP4 P[8] type. The VP7 gene shared a higher nucleic acid and amino acid homology with the porcine G5 strain CC117 (90 and 96%, respectively) than with human G5 strain IAL-28 (86 and 92%, respectively). Phylogenetic analysis showed Cameroonian strain MRC3105 clustered together in the same lineage as two other reported porcine G5 strains. The Cameroonian G5 strain, the first to be reported in humans outside of Latin America, may be a natural reassortant between animal and human rotavirus strains.
Determination of the G and P types of previously nontypeable rotavirus strains from the African Rotavirus Network, 1996-2004: Identification of unusual G types
(Journal of Infectious Disease, 2010) Esona, M.D.; Steele, A.D.; Kerin, T.; Armah, G.E.; Peenze, I.; Geyer, A.; Page, N.; Nyangao, J.; Agbaya, V.A.; Trabelsi, A.; Tsion, B.; Aminu, M.; Sebunya, T.; Dewar, J.; Glass, R.; Gentsch, J.
A total of 215 nontypeable rotavirus samples collected from children <5 years of age by members of the African Rotavirus Network were characterized using reverse-transcription polymerase chain reaction analysis and sequencing. The most predominant strain identified was P[8]G1 (46.9%). Genotypes P[8]G10, P[8]G8, P[6]G8, and P[7]G5 were also detected at frequencies varying from 0.5% to 2.3%. This study suggests that reassortment of unusual G types into a background of globally common genotype P[8] strains may be a major mechanism of generating rotavirus diversity. Nucleotide substitutions at the P[8], P[6], and G1 primer binding sites accounted for the failure to type these strains initially. Hence, these findings highlight the need for regular evaluation of rotavirus genotyping methods.
Distribution of rotavirus genotypes in the postvaccine introduction era in Ashaiman, Greater Accra Region, Ghana, 2014‐2016
(Journal of Medical Virology, 2019-07-03) Letsa, V.; Damanka, S.; Dennis, F.; Lartey, B.; Armah, E.G.; Betrapally, N.; Gautam, R.; Esona, M.D.; Bowen, M.D.; Quaye, O.
Group A Rotaviruses (RVAs) are the most important etiological agents of acute gastroenteritis (AGE) in children less than 5 years of age. Mortality resulting from RVA gastroenteritis is higher in developing countries than in developed ones, causing a huge public health burden in global regions like Africa and South‐East Asia. This study reports RVA genotypes detected in Ashaiman, Greater Accra Region, Ghana, in the postvaccine introduction era for the period 2014‐2016. Stool samples were collected from children less than 5 years of age who visited Ashaiman Polyclinic with AGE from November 2014 to May 2015 and from December 2015 to June 2016. The samples were tested by enzyme immunoassay (EIA), and one‐step multiplex reverse transcription polymerase chain reaction was performed on the EIA positive samples for gel‐based binomial genotyping. Of the 369 stool samples collected from children with AGE, 145 (39%) tested positive by EIA. Five VP7 (G1, G3, G9, G10, and G12) and three VP4 (P[4], P[6] and P[8]) genotypes were detected. Eight G/P combinations were identified of which, G3P[6], G12P[8], G1P[8], and G9P[4] were the most prevalent and responsible for 93 (68%) of the AGE cases, and seven mixed‐types were detected which represented 8% of the RVA cases. High prevalence, diversity, and mixed‐types of RVAs were detected from Ashaiman with the emergence of unusual genotypes.
Diversity of Rotavirus Strains Circulating in West Africa from 1996 to 2000
(The Journal of Infectious Diseases, 2010) Armah, G.E.; Steele, A.D.; Esona, M.D.; Akran, V.A.; Nimzing, L.; Pennap, G.
Evolutionary changes between pre- and post-vaccine South African group A G2P[4] rotavirus strains, 2003–2017
(Microbiology Society, 2022) Mwangi, P.N.; Page, N.A.; Seheri, M.L.; Mphahlele, M.J.; Nadan, S.; Esona, M.D.; Kumwenda, B.; Kamng’ona, A.W.; Donato, C.M.; Steele, D.A.; Ndze, V.N.; Dennis, F.E.; Jere, K.C.; Nyaga, M.M.
The transient upsurge of G2P[4] group A rotavirus (RVA) after Rotarix vaccine introduction in several countries has been a matter of concern. To gain insight into the diversity and evolution of G2P[4] strains in South Africa pre and post-RVA vaccination introduction, whole-genome sequencing was performed for RVA positive faecal specimens collected between 2003 and 2017 and samples previously sequenced were obtained from GenBank (n=103; 56 pre- and 47 post-vaccine). Pre-vaccine G2 sequences predominantly clustered within sub- lineage IVa-1. In contrast, post-vaccine G2 sequences clustered mainly within sub-lineage IVa-3, whereby a radical amino acid (AA) substitution, S15F, was observed between the two sub- lineages. Pre-vaccine P[4] sequences predominantly segregated within sub-lineage IVa while post-vaccine sequences clustered mostly within sub-lineage IVb, with a radical AA substitution R162G. Both S15F and R162G occurred outside recognised antigenic sites. The AA residue at position 15 is found within the signal sequence domain of Viral Protein 7 (VP7) involved in translocation of VP7 into endoplasmic reticulum during infection process. The 162 AA residue lies within the hemagglutination domain of Viral Protein 4 (VP4) engaged in interaction with sialic acid- containing structure during attachment to the target cell. Free energy change analysis on VP7 indicated accumulation of stable point mutations in both antigenic and non-antigenic regions. The segregation of South African G2P[4] strains into pre and post-vaccination sub-lineages is likely due to erstwhile hypothesized step-wise lineage/sub-lineage evolution of G2P[4] strains rather than RVA vaccine introduction. Our findings reinforce the need for continuous whole- genome RVA surveillance and investigation of contribution of AA substitutions in understanding the dynamic G2P[4] epidemiology.
Genomic characterization of human rotavirus G8 strains from the African rotavirus network: relationship to animal rotaviruses
(Journal of Medical Virology, 2009) Esona, M.D.; Geyer, A.; Page, N.; Trabelsi, A.; Fodha, I.; Aminu, M.; Agbaya, V.A.; Tsion, B.; Kerin, T.K.; Armah, G.E.; Steele, A.D.; Glass, R.I.; Gentsch, J.R.
Global rotavirus surveillance has led to the detection of many unusual human rotavirus (HRV) genotypes. During 1996-2004 surveillance within the African Rotavirus Network (ARN), six P[8],G8 and two P[6],G8 human rotavirus strains were identified. Gene fragments (RT-PCR amplicons) of all 11-gene segments of these G8 strains were sequenced in order to elucidate their genetic and evolutionary relationships. Phylogenetic and sequence analyses of each gene segment revealed high similarities (88-100% nt and 91-100% aa) for all segments except for gene 4 encoding VP4 proteins P[8] and P[6]. For most strains, almost all of the genes of the ARN strains other than neutralizing antigens are related to typical human strains of Wa genogroup. The VP7, NSP2, and NSP5 genes were closely related to cognate genes of animal strains (83-99% and 97-99% aa identity). This study suggests that the ARN G8 strains might have arisen through VP7 or VP4 gene reassortment events since most of the other gene segments resemble those of common human rotaviruses. However, VP7, NSP2 (likely), and NSP5 (likely) genes are derived potentially from animals consistent with a zoonotic introduction. Although al rotavirus strains.
Human G9P[8] rotavirus strains circulating in Cameroon, 1999-2000: Genetic relationships with other G9 strains and detection of a new G9 subtype
(Infection, Genetics and Evolution, 2013-08) Esona, M.D.; Mijatovic-Rustempasic, S.; Foytich, K.; Roy, S.; Banyai, K.; Armah, G.E.; Steele, A.D.; Volotão, E.M.; Gomez, M.M.; Silva, M.F.M.; Gautam, R.; Quaye, O.; Tam, K.I.; Forbi, J.C.; Seheri, M.; Page, N.; Nyangao, J.; Ndze, V.N.; Aminu, M.; Bowen, M.D.; Gentsch, J.R.
Group A rotaviruses (RV-A) are the leading cause of viral gastroenteritis in children worldwide and genotype G9P[8] is one of the five most common genotypes detected in humans. In order to gain insight into the degree of genetic variability of G9P[8] strains circulating in Cameroon, stool samples were collected during the 1999-2000 rotavirus season in two different geographic regions in Cameroon (Southwest and Western Regions). By RT-PCR, 15 G9P[8] strains (15/89. =. 16.8%) were identified whose genomic configurations was subsequently determined by complete or partial gene sequencing. In general, all Cameroonian G9 strains clustered into current globally-spread sublineages of the VP7 gene and displayed 86.6-100% nucleotide identity amongst themselves and 81.2-99.5% nucleotide identity with global G9 strains. The full genome classification of all Cameroonian strains was G9-P[8]-I1-R1-C1-M1-A1-N1-T1-E1-H1 but phylogenetic analysis of each gene revealed that the strains were spread across 4 or more distinct lineages. An unusual strain, RVA/Human-wt/CMR/6788/1999/G9P[8], which shared the genomic constellation of other Cameroonian G9P[8] strains, contained a novel G9 subtype which diverged significantly (18.8% nucleotide and 19% amino acid distance) from previously described G9 strains. Nucleotide and amino acid alignments revealed that the 3' end of this gene is highly divergent from other G9 VP7 genes suggesting that it arose through extensive accumulation of point mutations. The results of this study demonstrate that diverse G9 strains circulated in Cameroon during 1999-2000. © 2013.
Molecular epidemiology of rotavirus infection in Western Cameroon
(Journal of Tropical Pediatrics, 2003-06) Esona, M.D.; Armah, G.E.; Steele, A.D.
Rotavirus is major viral cause of diarrhoea in children worldwide. In this study, the first from Cameroon, the molecular epidemiology of rotavirus infection was investigated. Eight hundred and ninety diarrhoea stools collected from children under the age of 5 years in Western Cameroon between 1999 and 2000 were analysed for rotaviruses and further characterized by antigenic and genomic methods. Rotaviruses were detected in 21.9 per cent of stools and were highest during the cool dry season. Sixteen different electrophoretic patterns, 13 of long and three of short, were detected in the study area. The predominant subgroup detected was subgroup II (66.9 per cent) and atypical strains with long electropherotype, but subgroup I specificity were also observed. Rotavirus infection was shown to be an important component of diarrhoeal disease in young children in Cameroon. The results of this study in Cameroon reinforces the need to continue with surveillance programmes in Africa.
Novel human rotavirus genotype G5P[7] from child with diarrhea, Cameroon
(Emerging Infectious Diseases, 2009) Esona, M.D.; Geyer, A.; Banyai, K.; Page, N.; Aminu, M.; Armah, G.E.; Hull, J.; Steele, A.D.; Glass, R.I.; Gentsch, J.R.
We report characterization of a genotype G5P[7] human rotavirus (HRV) from a child in Cameroon who had diarrhea. Sequencing of all 11 gene segments showed similarities to > or =5 genes each from porcine and human rotaviruses. This G5P[7] strain exemplifies the importance of heterologous animal rotaviruses in generating HRV genetic diversity through reassortment.
Rotavirus VP4 and VP7 Genotypes Circulating in Cameroon: Identification of Unusual Types
(The Journal of Infectious Diseases, 2010) Esona, M.D.; Armah, G.E.; Steele, A.D.
Rotavirus remains a priority candidate for vaccine development, because it is the major cause of viral diarrhea in children worldwide. This study characterized rotavirus strains in 195 stool specimens collected from children! 5 years of age with diarrhea, in the Southwest Province and Western Province of Cameroon during 1999– 2000. The predominant G type was G1 (detected in 44.9% of specimens) and the most predominant P type was P [8] (in 82.7%). The most common G-P combination detected was G1P [8] (in 37.1% of specimens), followed by G9P [8] (in 14%). Rotavirus strains with unusual G-P combinations, such as G1P [4], G2P [8], G8P [8], G9P [4], G5P [8], and G10P [8], were also observed in significant numbers. Analysis of the age distribution showed that G1P [8] was found circulating in all age groups except in infants!6 months old. Strains G2P [4] and G3P [8] were identified in children 137 months and 19–24 months of age, respectively. Strain G9P [8] was found circulating among children 125 months of age. Unusual strains and mixed infections were found circulating in the different age groups, albeit at lower levels. The high prevalence of mixed infections and diversity of rotavirus strains detected in this first study based on genotyping of Cameroonian strains reinforce the need to continue with surveillance programs in Africa, where a high diversity of strains has been reported.