Merja Roivainen

Induction of interferon-a in human leukocytes by polioviruses: Wild-type strains are better inducers than attenuated strains

Cultures of human peripheral blood leukocytes were exposed to different poliovirus strains at a multiplicity of infection of 1 TCID50/cell. Induction of interferon was a regular phenomenon in the cultures but the maximal yields varied between experiments. Resistance to moderate temperature (56 degrees) and pH 2, as well as antigenic properties, indicated that most of the activity was due to interferon-alpha. Low levels of interferon-gamma were also measured in the cultures using a radioimmunoassay. Using kinetic uv-inactivation we found that infectivity of the virus preparations was affected more rapidly than the capability to induce interferon-alpha. Dependence of interferon-alpha yields on the inducing virus strain was examined in 46 independent cultures by comparing the three serotypes of the attenuated poliovirus vaccine strains and two wild-type strains of serotype 3 (Saukett and P3/FIN/23127/84). The wild-type strains were significantly better inducers of interferon than the attenuated strains (P less than 0.001). Four other wild-type strains representing all serotypes tested in 12 independent cultures were also better interferon inducers than the corresponding Sabin strains (P less than 0.02). Induction of interferon may have a role in the poliovirus-induced inhibition of lymphocyte mitogenesis previously reported by others.

Human rhinoviruses in INDIS-study material-evidence for recovery of viable rhinovirus from fecal specimens

The significance of human rhinoviruses (HRV) as prevailing respiratory pathogens has sharpened during the recent years followed by implementation of molecular methods in detection. Rhinoviruses are detected exceedingly in hospitalized cases of respiratory infection with varying severity, in addition to being frequent in cases of common cold. The aim of this study was to evaluate occurrence of HRV in a prospective study material. The prospective INDIS material comprises nasopharyngeal (Nu2009=u2009429) and fecal (Nu2009=u2009425) specimens from children under 11 years of age collected during any clinical infection. Validated real‐time RT‐PCR assays were applied for the detection of HRV. HRV were detected numerously not only in the nasopharyngeal specimens, but a myriad also in fecal specimens, 236 (55.0%) and 149 (35.1%), respectively, fecal findings actually beyond anticipation. A total of 13 of HRV‐positive fecal specimens were selected for genetic typing in the VP4/VP2 coding region. HRV‐A strains were detected in seven specimens: HRV‐A9, ‐A10, ‐A24, ‐A49, ‐A56 and ‐A82. HRV‐B—strains were detected three times: HRV‐B42 and ‐B79, and HRV‐C twice: HRV‐C12 and HRV‐Cpat4. HRV‐B42 also showed cytopathic effect in cell culture, confirmed by real‐time RT‐PCR and VP4/VP2 sequencing, suggesting presence of viable HRV in fecal specimens. J. Med. Virol. 85:1466–1472, 2013.

Effect of Host Proteases on Early Steps of Enterovirus Infection

Enteroviruses, a genus in the family of Picornaviridae,are small non-enveloped animal viruses with a messenger-sense genomic RNA and an icosahedral capsid composed of 60 copies each of four structural proteins.1 There are about 70 different serotypes of enteroviruses isolated from man and a lot of others that infect domestic or wild animals. Because of their significance in public health the three serotypes of polioviruses, the causative agents of poliomyelitis, have been as targets of the most intensive research during the last a few decades. Other enteroviruses, although known for long to be medically important as well, have only recently acquired more specific attention. These studies have revealed interesting individual characteristics of various non-polio enteroviruses on top of the previously known antigenic differences.1–4