Neutralization of adenovirus toxins: specificity and antigenic relationships

Characteristics of mastadenovirus h 8, the causative agent of epidemic keratoconjunctivitis

Adenovirus 8 (Ad 8, strain 1127) has the general structural features of an adenovirus; it produces the genus-specific hexon antigen. The fiber length of 12 nm corresponds to that of other subgenus D adenoviruses. In hemagglutination-inhibition, Ad 8 is related to Ad9 and Ad 15/H9. The slow multiplication, compared to most other subgenus D viruses, was shown not to be caused by an extended growth cycle, but appears to be due to an inefficient virus release into the medium. After restriction analysis with the enzymes Sma I and Bgl II, the typical fragment patterns of species from subgenus D were obtained, while very different patterns emerged from the analysis with Hind III, Bam HI, and Bst E II endonucleases. Several strains of Ad 8 produced more penton-associated toxin than Ad 15/H9 used as reference virus from subgenus D, which could explain the "clumping CPE" caused by Ad 8. Ad 8 toxin was neutralized by antisera from many adenovirus species. The poor virus yield of Ad 8 was not improved by removing soluble viral or cellular substances; all other attempts to improve virus yield by varying the conditions of cell culture also failed.

Neutralization of adenovirus infectivity and cytotoxin in various cell cultures

The neutralization of human adenovirus 5 and 11 by homologous and heterologous rabbit antisera was determined by CPE inhibition in various cell cultures (HeLa, HEL, Vero, secondary kidney cells from cercopithecus, rabbit, mouse), or in HeLa cells made impermissive by IUdR inhibition. The results concerning sensitivity and specificity were similar in all cases. Crude and purified virus showed similar neutralization. Immunofluorescence neutralization in HeLa cell cultures gave similar results; this method is suitable for demonstrating subtle immunological relations between adenovirus types. The neutralization of the early cytopathic factor ('cytotoxin') showed a pattern of cross-reactivity different from the virion; the cytotoxin was found to be active in part of the cell cultures only. It is concluded from the results that the virus function(s) blocked by antibody appear to be identical for the replicative cycle in infection and for the initiation of the abortive infection in non-permissive cells. Hence, either kind of cells may be used for neutralization tests.