Possible outcomes of reassortment in vivo between wild type and live attenuated influenza vaccine strains.
Reassortment of influenza viruses in nature has been well documented. Genetic reassortment plays a key role in emergence of new influenza A strains, including pandemic viruses. Permissive host can be simultaneously coinfected with multiple influenza viruses. During genetic reassortment gene segments are exchanged between parental viruses that may lead to some enhancement of virulence of reassortant progeny. At present, vaccination with live attenuated cold-adapted (ca) reassortant vaccine (LAIV) is used as an effective public health measure for influenza prophylaxis. However, there are concerns about a potential of simultaneous infection of human host with ca and wild type (wt) influenza viruses which might produce progeny that contain novel, more virulent genotypes. The aim of this study was to investigate potential consequences of reassortment of wt with LAIV strains in vivo. We demonstrated that reassortment of wt viruses with ca strains in guinea pigs have resulted in progeny virus which caused reduced macroscopic lesions of chicken embryos. According to phenotypical data 95% (19 out of 20) isolated reassortants were restricted in replication at elevated temperature of 40°C. None of reassortants were more virulent than wt parents, or revealed significantly higher macroscopic lesions than wt parental viruses. Our results suggest that genetic reassortment between wt and vaccine strain is unlikely to lead to virulent reassortant progeny. These findings provide additional support of LAIV safety data.
Institute of Experimental Medicine, RAMS, St. Petersburg, Russia. irina.v.kiseleva@mail.ru
Irina
I
Kiseleva
Irina
I
Dubrovina
Ekaterina
E
Bazhenova
Ekaterina
E
Fedorova
Natalie
N
Larionova
Larisa
L
Rudenko
D000818:Animals; D005260:Female; D006168:Guinea Pigs; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects; D009975:Orthomyxoviridae / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D009976:Orthomyxoviridae Infections / Q000473:pathology / Q000821:virology; D016865:Reassortant Viruses / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D011995:Recombination, Genetic; D016896:Treatment Outcome; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000009:adverse effects; D014774:Virulence
D007252:Influenza Vaccines; D014613:Vaccines, Attenuated