RECOVERY OF HUMAN PARAINFLUENZA VIRUS TYPE-ONE AND TYPE-2

The ability to recover human parainfluenza virus types 1 and 2 (HPIV-1 , 2) from infected individuals has been highly variable. During the au tumn of 1991, 158 nasal wash, specimens collected from children with l ower respiratory symptoms were split and cultured independently at two laboratories using different tissue culture techniques. Immunofluores cent antibody (IFA) and hemadsorption (HAd) assays were compared for t heir speed and efficiency in viral detection. 45 isolates [HPIV-1 (17) and HPIV-2 (28)] were recovered by one laboratory and only one (HPIV- 2) by the other. IFA was the most sensitive assay. detecting 87% of HP IV-1 and 70% of HPIV-2 by the fourth day of culture, HAd assay detecte d 87% of HPIV-1 isolates by the time they were positive by IFA, but on ly 35% of the HPIV-2 isolates. Significant methodologic differences be tween laboratories were then compared simultaneously for effect on vir us recovery from culture positive frozen clinical specimens. Recovery of 100% of the isolates was achieved. Factors that contributed to diff erences in recovery of HPIV-1 and 2 were: (1) primary African green mo nkey (AGMK) cells were inferior to cynomolgus monkey kidney or LLC-MK( 2) cells, (2) addition of trypsin to culture medium for AGMK and LLC-M K(2) cells enhanced recovery, (3) use of IFA was essential for rapid d etection of HPIV-2, and (4) use of microtiter plate culture without sp ecimen dilution enhanced virus recovery. A survey of clinical virology laboratories demonstrated considerable variability in the use of thes e techniques for routine respiratory virus culture.