Measles surveillance in Taiwan, 2012-2014: Changing epidemiology, immune response, and circulating genotypes: Measles Surveillance in Taiwan, 2012-2014

Global genetic diversity of measles virus (Paramyxoviridae: Morbillivirus: Morbillivirus hominis): historical aspects and current state

Monitoring the circulation of the measles virus and studying its genetic diversity is an important component of the measles elimination program. A methodological approach to molecular genetic studies and their interpretation in the measles surveillance was developed in the early 2000s. During its development, clear areas of circulation of each genotype of the virus were identified, therefore, the determination of viruses' genotypes was proposed to monitor circulation and identify transmission pathways. However, in the future, due to a significant decrease in the number of active genotypes, an approach based on sub-genotyping was proposed: determining not only the genotype of the virus, but also its genetic lineage/genetic variant. The Global Measles and Rubella Laboratory Network (GMRLN) systematically monitors the circulation of the measles virus at the sub-genotypic level, depositing the results in a specialized database MeaNS2. It is this database that is the most complete and reliable source of information about the genetic characteristic of measles viruses. This review presents both historical information and the latest data on the global genetic diversity of the measles virus.

Genetic Characteristics of Measles Viruses Isolated in Taiwan between 2015 and 2020

A genetic analysis of circulating measles virus (MeV) provides strong evidence of an interruption in endemic measles and supports the elimination status of this disease. This study investigated 219 MeVs isolated between 2015 and 2020. Based on the 450 nucleotide sequences of the nucleoprotein gene (N-450), three genotypes of the H1, D8 and B3 with 8, 18 and 6 different N-450 sequences, respectively, were identified. The H1 genotype virus has not circulated in Taiwan since 2017, and the D8 and B3 genotype MeVs became dominant between 2018 and 2019. Different D8 genotype variants were imported from neighboring countries, and the majority of MeV variants were detected only for a short period. However, MVs/Gir Somnath.IND/42.16[D8], a named strain designated by the World Health Organization (WHO), was detected over 2 years. To explore whether the endemic transmission of measles has been underestimated, another sequence window of the hypervariable, noncoding regions between the matrix (M) and fusion (F) genes (MF-NCR) was introduced to clarify the transmission chain. From the chronological sequence analysis of MeVs with N-450 and MF-NCR sequence windows, no endemic MeV variants lasted over 4 weeks, providing strong evidence to support the contention that Taiwan has reached the status for measles elimination.

Occurrence of measles genotype D8 during a 2014 outbreak in Banjarmasin, South Kalimantan, Indonesia

OBJECTIVES

An outbreak of measles symptoms occurring in children in Banjarmasin, South Kalimantan, Indonesia in 2014 was investigated.

METHODS

Nasal swabs were collected from 23 children (median age 41 months) with fever and other symptoms of measles hospitalized in Ulin General Hospital and Islamic Hospital, Banjarmasin, South Kalimantan. Viral RNA was extracted for cDNA synthesis, followed by PCR and sequencing using paramyxovirus family consensus and N-gene primers.

RESULTS

Sixteen measles-positive patients (70%) were identified. Fifteen virus strains belonged to genotype D8 and the remaining one strain was confirmed as belonging to genotype D9.

CONCLUSION

Measles virus genotype D8 was detected in an outbreak of measles in South Kalimantan, Indonesia, in 2014.