These results demonstrate that some reassortants between pandemic (H1N1) 2009 and seasonal influenza A (H3N2) were viable, remained transmissible, and were more pathogenic than the wild-type pandemic (H1N1) 2009 virus and emphasize the importance of monitoring reassortant viruses in surveillance programs because reassortment events may affect pathogenicity.
Moreover, there is evidence that atypical strains are more pathogenic in congenital toxoplasmosis than type II strains [ 34, 38, 40] and that they can lead to reinfection in pregnant women with a past immunity to type II strains [ 38].
Some S. suis strains are more pathogenic than others with 2 sequence types (ST), ST1 and ST7, being well recognized as highly pathogenic.
The potential importance of this finding is relevant to L-type BSE, which based on experimental transmission into humanized PrP transgenic mice and macaques, suggests that L-type BSE is more pathogenic for humans than typical BSE (24, 38 ).
As shown in Figure 7, the color mutants were more pathogenic to the insect than the wild type strain Af293.
Moreover, some wild-type H5N1 isolates may be more pathogenic in quails than the A/Swan/Nagybaracska/01/06(H5N1) challenge virus, hence requiring higher levels of immune responses for protection.
Collectively, these results argue that development of the next generation live attenuated vaccine for Francisella should be based on use of the less pathogenic type B biovar rather than the more reactogenic type A biovar.
Restriction fragment length polymorphism type 1-8-4, onlyrring in only 7 cases, was also included for analysis, because this virus type emerged in Ontario during the study period [ 7] This RFLP type is also of interest because an isolate of RFLP type 1-8-4 known as MN184 has been reported to be more likely to be transmitted by aerosol than a less pathogenic type [ 13].
However, the present study demonstrated that its cell wall is capable of stimulating the type of maladaptive inflammatory response typically associated with far more pathogenic gram-positive bacteria.
Although significant efforts have been made to reduce occupational and environmental exposure to amphibole types of asbestos (crocidolite, amosite) that may be more pathogenic in mesothelioma (Mossman and Gee 1989), the use of chrysotile asbestos continues worldwide (Nicholson 1997).
