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Type 3 poliovirus/Finland/1984 is genetically related to common Mediterranean strains
T Pöyry1, L Kinnunen, J Kapsenberg
1Department of Virology and Molecular Biology Unit, National Public Health Institute, Helsinki, Finland.
Abstract:
Strains of poliovirus type 3 isolated in Finland in 1984 and 1985 (P3/Fin/84) are known to differ considerably from the type 3 vaccine strains in both nucleotide sequence and antigenic properties. In the search for the origin of the outbreak we first tested 80 type 3 strains that had been isolated elsewhere in the world during the years 1953 to 1986. An oligonucleotide probe complementary to a highly variable 17 nucleotide interval in the 5' non-coding region of the genomic RNA of P3/Fin/84 reacted with five strains. Also it was revealed that two of the latter five strains were related to the P3/Fin/84 strains in two separate genomic regions compared after partial RNA sequencing. One of them was isolated in Switzerland in 1980 and the other in Turkey in 1981. The Swiss strain was from a patient who had recently returned from a journey to various Mediterranean countries. Consequently, 16 other strains isolated in the late 1970s and early 1980s in Europe or in the Mediterranean countries were studied in detail by partial genomic sequencing and with neutralizing monoclonal antibodies. Two separate regions of the genome were compared by sequencing and corresponding dendrograms were constructed. The Switzerland and Turkey strains were found to be the strains most closely related to the viruses of the 1984 Finland epidemic. These results indicate that type 3 poliovirus strains related to P3/Fin/84 had been circulating in Mediterranean countries since the late 1970s.
Insights
Poliovirus type 3 strains causing an outbreak in Finland were linked to viruses circulating in Mediterranean countries. Genetic sequencing identified related strains in Switzerland and Turkey, suggesting a common origin.
Area of Science:
- Virology
- Epidemiology
- Molecular Biology
Background:
- Poliovirus type 3 strains (P3/Fin/84) isolated in Finland during 1984-1985 exhibited significant genetic and antigenic differences from vaccine strains.
- The origin of these distinct Finnish poliovirus strains was unknown, necessitating an investigation into their epidemiological links.
Purpose of the Study:
- To determine the origin of the P3/Fin/84 poliovirus type 3 strains.
- To identify related poliovirus strains circulating globally, particularly in Europe and the Mediterranean region.
Main Methods:
- Screening of 80 type 3 poliovirus strains (1953-1986) using an oligonucleotide probe targeting a variable region of the viral RNA.
- Partial genomic RNA sequencing and analysis of two distinct genomic regions for relatedness.
- Characterization using neutralizing monoclonal antibodies.
Main Results:
- An oligonucleotide probe identified five related type 3 poliovirus strains.
- Partial sequencing revealed two of these strains, isolated in Switzerland (1980) and Turkey (1981), were closely related to the P3/Fin/84 strains.
- Further analysis of 16 European and Mediterranean strains confirmed the close relationship of the Swiss and Turkish isolates to the Finnish epidemic strains.
Conclusions:
- Poliovirus type 3 strains genetically related to the Finnish outbreak viruses (P3/Fin/84) were circulating in Mediterranean countries as early as the late 1970s.
- The findings suggest a potential epidemiological link between poliovirus circulation in the Mediterranean region and the subsequent outbreak in Finland.