National Immunization Program Vaccines Research Articles

As a part of strategy to control diarrheal diseases, World Health Organization (WHO) recommends to include rotavirus vaccines in national immunization programs. Sentinel surveillance networks have been established to monitor rotavirus disease burden and genotype distribution in both pre and post vaccine era in many countries. Unfortunately, due to lack of proper surveillance programs, data on rotavirus disease burden and genotype distribution from Pakistan is scarce. We investigated 502 stool samples from children (< 5 years) hospitalized due to gastroenteritis in Rawalpindi, Pakistan during 2014 for the presence of group A rotavirus (RVA) and its genotypic diversity. Among 147 ELISA positive samples, 131 were successfully genotyped for RVA. Common G types detected were G1 (23.6%), followed by G3 (22.9%), G12 (19.8%), G2 (19.08%) and G9 (9.9%). The most common P-type was P[8] (41.2%), followed by P[6] (29%) and P[4] (28.24%). G3P[8] (17.55%) was the most prevalent genotype combination followed by G12P[6] (16.7%), G2P[4] (15.2%) and G1P[8] (14.5%). Mixed infection of rotavirus G-P types was also observed in 6% of samples. Phylogenetic analysis of VP7 and VP4 genes of Pakistani strains showed that G1, G2, G9 and P[4], P[6], P[8] were closely related to strains circulating worldwide as well as previously reported strains from Pakistan. Pakistani G12P[8] strains NIH-BBH-3981 and NIH-BBH-4003 belonged to lineage 3 cluster 3a along with strains from USA and Italy whereas G12P[6] strains NIH-BBH-3978, NIH-BBH-4052 and NIH-BBH-4444 were closely related to strains from Italy, Thailand, United Kingdom and with previously reported G12 strains from Pakistan within lineage 3 cluster 3b. This pre-vaccination data supports the need for RVA vaccine inclusion at our national level and will be helpful in assessing the effect of vaccination on RVA genotype diversity due to vaccine selection pressure once post-vaccination data becomes available.

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