Biochemical studies on adenovirus multiplication. XVI. Transcription of the adenovirus genome during abortive infection of elevated temperatures

First detection of enteric adenoviruses genotype 41 in recreation spring areas of Taiwan

Human adenoviruses (HAdVs) are DNA viruses found in recreational water, such as water parks and swimming pools. Human adenovirus 41 (HAdV-41) is the most common serotype detected and is a leading cause of acute diarrheal disease. The focus of this study is to determine the prevalence of HAdVs in hot springs. Of 57 samples collected from four different geological sites, 16 samples have shown evidence of HAdVs (28.1%). HAdV-41 and porcine adenovirus 5 (PAdV-5) were the two types isolated, with a greater frequency of HAdV-41, which in other settings has been associated with acute diarrhea. The highest occurrence was found in private hot tubs/Yuya (37.5%), followed by an outlet of hot springs (30.8%); public pools and foot pools shared the same detection rate of 21.4% (3/14). However, there was no evidence supporting a link between water quality indicators and HAdV detection rate. From a phylogenic analysis and BLAST against the NCBI database, it was concluded that HAdV-41 obtained from hot spring areas are closely related to global environmental genotypes.

Effects of febrile temperature on adenoviral infection and replication: implications for viral therapy of cancer

We previously conducted a phase I/II study using arterial infusions of ONYX-015 (dl1520), a replication-selective adenoviral vector, with E1b deleted, for patients with metastatic colorectal cancer. No dose-limiting toxicities occurred, but >90% of the patients experienced fever. The effects of temperature on the replication of dl1520 in normal and transformed cells had not been studied. Therefore, replication and cell viability assays were performed with a panel of nontransformed and transformed cell lines cultured at 37 and 39.5 degrees C and treated with adenovirus type 5 (Ad5) or dl1520. Ad5-mediated cytolytic effects were inhibited and production of infectious particles decreased by >1,000-fold in the nontransformed cells at 39.5 degrees C. Seven of nine of the tumor cell lines retained significant cell-killing effects when treated with Ad5 at 39.5 degrees C. When dl1520 was used, no cytolytic effects were observed at 39.5 degrees C in the nontransformed cell lines; however, cytolytic effects occurred in six of nine tumor cell lines at 39.5 degrees C. Notably, a subset of the tumor cell lines demonstrated increased dl1520-mediated cytolytic effect and replication at 39.5 degrees C. Suppression of Ad5 and dl1520 replication at 39.5 degrees C was not related to p53 status or HSP70 expression. Also, at 39.5 degrees C, E1a expression was inhibited in nontransformed cells but was still abundant in the transformed cells, indicating that a novel early block in viral replication occurred in the nontransformed cells. Fever may therefore augment the therapeutic index of oncolytic viruses by inhibiting replication in normal cells while permitting or enhancing viral replication in some tumor cells.

Synthesis of viral ribonucleic acid during restricted adenovirus infection

The mechanism by which simian virus 40 converts the abortive adenovirus type 7 infection of monkey cells into an efficient lytic infection has been investigated. Analysis of ribonucleic acid (RNA) synthesis during unenhanced and enhanced infection of monkey cells has shown that adenovirus RNA synthesized in the abortive infection contains both "early" and "late" sequences. In hybridization competition experiments, early adenovirus RNA from human cells prevented the hybridization of only 20% of the adenovirus RNA transcribed in unenhanced infection. Further, the RNA from unenhanced cells was able to completely block the hybridization of RNA synthesized during enhanced infection. Finally, virus-associated RNA, which is a late RNA transcribed in lytic adenovirus infection, is also produced in the unenhanced infection. An accompanying paper describes a marked deficiency in adenoviral capsid protein synthesis in the unenhanced infection. We conclude that RNA sequences, which are sufficient to code for the synthesis and assembly of structural proteins of adenovirus, are transcribed but are not efficiently translated in the unenhanced adenovirus infection of monkey cells.

Synthesis of virus-specific ribonucleic acid in KB cells infected with type 2 adenovirus

By using the technique of deoxyribonucleic acid (DNA)-ribonucleic acid (RNA) hybridization, virus-specific RNA (cRNA) was detected 6 hr after infection in preparations of total RNA from cells infected with type 2 adenovirus in the presence of 2 mum 5-fluorodeoxyuridine. In the absence of 5-fluorodeoxyuridine, there was a continuous increase in the incorporation of (3)H-uridine into viral cRNA until 20 hr after infection, at which time approximately 40% of the (3)H-uridine entering RNA was found in virus-specific RNA. When RNA was prepared from polyribosome fractions obtained from cytoplasmic extracts of infected cells, virus-directed transcription was detected at 3 hr after infection (i.e., 3 to 4 hr before the initiation of viral DNA synthesis). Viral cRNA species synthesized at different times after infection were compared by the technique of DNA-RNA hybridization-inhibition ("presaturation" hybridization-competition). Three hybridization-inhibition techniques were compared. The techniques differed in the manner in which the DNA-RNA complex was isolated after the first hybridization reaction. Depending on the procedure employed, various degrees of inhibition were measured. The variation could be essentially eliminated if prior to hybridization the inhibitory RNA species were alkali-degraded to a uniform size of about 4S. Undegraded RNA could be used if the DNA-RNA complex was isolated by using a procedure involving rigorous washing (preferably including ribonuclease treatment) before the second hybridization with labeled RNA. When a rigorous hybridization-inhibition procedure was used, three classes of virus-specific RNA species could be distinguished: (i) early RNA class I whose synthesis began prior to viral DNA replication and stopped at some time after the initiation of viral DNA replication-it comprised about 70% of the early RNA species and was apparently degraded by 18 hr after infection; (ii) early RNA class II whose synthesis began prior to viral DNA replication and apparently continued at an enhanced rate late in infection; and (iii) late RNA whose synthesis began after the initiation of viral DNA synthesis.

Effects of elevated temperatures on mengovirus ribonucleic acid synthesis and virus production in Novikoff rat hepatoma cells

The production of mengovirus in Novikoff rat hepatoma cells is progressively reduced with an increase in incubation temperature of the cells from 34 to 40 C, in spite of the fact that about the same amounts of single-stranded and double-stranded viral ribonucleic acid (RNA) are synthesized at 34, 37, and 40 C; the rate of overall protein synthesis is as high at 40 C as at 37 C. At 40 C, progeny viral RNA accumulates in an undegraded form without being incorporated into virus particles. The results suggest that virus maturation is preferentially inhibited at supraoptimal temperatures. At 42 C, on the other hand, no viral RNA is produced and no viral RNA polymerase activity is detectable in cell lysates. Failure of infected cells to form viral RNA polymerase at 42 C is probably due to an impairment of protein synthesis since most of the polyribosomes are rapidly lost during incubation at 42 C and the rate of amino acid incorporation into protein is 70% lower at 42 C than at 37 C. When infected cells are shifted from 37 to 42 C during the period of active viral RNA synthesis, viral RNA polymerase activity is rapidly lost from the cells, and viral RNA synthesis ceases within 45 min. In contrast, the RNA polymerase is as active in vitro at 42 C as at 37 C, and the activity is relatively stable at 42 C.