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Human adenoviruses (HAdVs) usually cause asymptomatic or mild infection, but infrequently, they are responsible for various severe syndromes including neurological disorders. Various research studies have investigated the association of HAdVs with acute flaccid paralysis (AFP). The purpose of this study was to investigate the genetic diversity of HAdVs and their association with AFP. Stool samples from patients ≤ 12 years of age with suspected AFP were collected from all over Pakistan within the framework of poliovirus surveillance. Poliovirus- and enterovirus-negative samples were screened for HAdVs. For virus isolation, the human epithelial cell line HEp-2c was used, culture-positive samples were screened by nested PCR assay, and partial hexon gene sequences were used for genotype identification. Out of 172 samples, 94 were positive by virus isolation, 89 were positive by PCR, and 32 isolates were genotyped successfully. Phylogenetic analysis showed that the HAdVs belonged to species A (HAdV-A12 and A31), B (HAdV-B3 and B7), C (HAdV-C1 and C6), D (HAdV-D19 and D93), and F (HAdV-F41), showing 99-100% nucleotide sequence identity and 98.3-100% amino acid sequence identity). Most of these genotypes have been reported previously in AFP cases, but this is the first report of the detection of HAdV-D93 in stool samples from AFP cases. The detection of a significant fraction of the HAdVs genotypes indicates that these genetically distinct genotypes are circulating in Pakistan and suggests their possible role in the pathogenesis of AFP. [ABSTRACT FROM AUTHOR]

Background Pakistan is among 3 countries endemic for wild poliovirus type 1 (WPV1) circulation that are still struggling for eradication of poliomyelitis. Active clinical and environmental surveillance with meticulous laboratory investigations provide insights into poliovirus transmission patterns and genomic diversity to inform decisions for strategic operations required to achieve eradication. Methods We analyzed epidemiological and virological data to comprehend the current epidemiological status of WPV1 in Pakistan during 2015–2017. Stool specimens of patients with acute flaccid paralysis (AFP) and sewage samples collected from 60 environmental sites were tested. Viral culturing, intratypic differentiation by real-time polymerase chain reaction, and nucleic acid sequencing of the VP1 region of the poliovirus genome to determine genetic relatedness among WPV1 strains were applied. Results Poliovirus isolates were grouped into 11 distinct clusters, which had ≥95% nucleotide homology in the VP1 coding region. Most of the poliovirus burden was shared by 3 major reservoirs: Karachi, Peshawar, and Quetta block (64.2% in 2015, 75.4% in 2016, and 76.7% in 2017). Conclusions Environmental surveillance reveals importations and pockets of unimmunized children that dictate intensive target mop-up campaigns to contain poliovirus transmission. A decrease in the number of orphan isolates reflects effective combination of AFP and environmental surveillance in Pakistan. The genetic data reflect sustained transmission within reservoir areas, further expanded by periodic importations to areas of high immunity reflected by immediate termination of imported viruses. Improved immunization coverage with high-quality surveillance is vital for global certification of polio eradication. [ABSTRACT FROM AUTHOR]