Fresh frozen plasma (FFP) is prepared in blood banks world-wide as a by- product of red blood cell concentrate preparation. Appropriate clinical use is for coagulation factor disorders where appropriate concentrates are unavailable and when multiple coagulation factor deficits occur such as in surgery. Viral safety depends on donor selection and screening; thus, there continues to be a small but defined risk of viral transmission comparable with that exhibited by whole blood. We have prepared a virus sterilized FFP (S/D-FFP) by treatment of FFP with 1% tri(n-butyl)phosphate (TNBP) and 1% Triton X-100 at 30 degrees C for 4 hours. Added reagents are removed by extraction with soybean oil and chromatography on insolubilized C18 resin. Treatment results in the rapid and complete inactivation of greater than or equal to 10(7.5) infectious doses (ID50) of vesicular stomatitis virus (VSV) and greater than or equal to 10(6.9) ID50 of sindbis virus (used as marker viruses), greater than or equal to 10(6.2) ID50 of human immunodeficiency virus (HIV), greater than or equal to 10(6) chimp infectious doses (CID50) of hepatitis B virus (HBV), and greater than or equal to 10(5) CID50 of hepatitis C virus (HCV). Immunization of rabbits with S/D-FFP and subsequent adsorption of elicited antibodies with untreated FFP confirmed the absence of neoimmungen formation. Coagulation factor content was comparable with that found in FFP. Based on these laboratory and animal studies, together with the extensive history of the successful use of S/D-treated coagulation factor concentrates, we conclude that replacement of FFP with S/D-FFP, prepared in a manufacturing facility, will result in improved virus safety and product uniformity with no loss of efficacy.
Polymerase chain reaction (PCR) and newer serologic assays for hepatitis C virus (HCV) were used to investigate 19 HCV cross-challenge episodes in chimpanzees. In these cross-challenges, 59% showed seroconversion after challenge, 33% showed reappearance of HCV-associated hepatocellular ultrastructural changes, 5 animals not PCR-positive at the time of challenge showed return of PCR positivity, and 26% developed hepatitis after rechallenge. A total of 74% showed at least one of these signs of reinfection. The frequency of development of serologic and ultrastructural responses was, however, reduced in secondary compared with primary infections (P less than .01). In 10 animals, the cross-challenge was done with heterologous strains, and in 9 with the originally infecting virus. There was no significant difference in the responses to homologous and heterologous challenges. The data suggest relatively weak immunity in HCV infections.
Hepatitis B virus (HBV) belongs to the genus Orthohepadnavirus of the family Hepadnaviridae. Having been found in various animals (duck, heron, woodchuck, ground squirrel, and primates), hepadnaviruses must have undergone a long history of evolution and may comprise more members than currently recognized. Chimpanzees may also have their own hepadnavirus, even if it might be very close to HBV. We analyzed HBV-like sequences from three chimpanzees (Pan troglodytes) that were most likely infected during their life in Africa in the wild. Two chimpanzees (Ch256 and Ch258) possessed a viral genome of 3182 nt in length with a 33-nt deletion in the preS1 region, which could not be classified into any of the six genotypes (A-F) of human HBV but was very homologous to a previously reported isolate from a London Zoo chimpanzee. Phylogenetically distinct from the HBV-like sequences from gibbons, orangutans, and a gorilla so far reported, the Ch256 and Ch258 isolates would represent an indigenous chimpanzee HBV (tentatively ChHBV). A third chimpanzee (Ch195) had a 3212-nt genome, classifiable into the genotype E of HBV. Because HBV-E has been found mostly in Africans, Ch195 may have been infected from a human source in Africa. However, an inverse scenario is also possible: a spread of HBV-E might have occurred from chimpanzees to humans a long time ago in Africa. Analysis of the arginine-rich C-terminal region of the core protein, which is well conserved among mammalian hepadnaviruses, indicated that HBV-E/F and nonhuman primate hepadnaviruses are much closer than HBV-A/B/C/D to the hepadnaviruses of woodchuck and ground squirrel. Our results support an "ex-nonhuman primate" hypothesis for the origin of HBV.
An open question for hepatitis C virus (HCV) vaccine development is whether the various genotypes of this virus protect against the development of chronic infection after heterologous infection with different genotypes. We approached this question by challenging chimpanzees that had recovered from HCV genotype 1a or 1b infection with 6 heterologous genotypes as well as with a homologous genotype (for chimpanzees originally infected with genotype 1a). All 9 chimpanzees rechallenged with a homologous genotype developed self-limited infections. Of 11 chimpanzees challenged with 100 chimpanzee infectious doses of heterologous genotypes, 6 developed self-limited infections, with peak viral loads in acute-phase serum that were ~5-fold lower than those seen during primary infections. One chimpanzee (which had recovered from genotype 1b infection and was rechallenged with genotype 6a) did not develop viremia but did show an anamnestic cell-mediated immune response after rechallenge. Four of the 11 chimpanzees rechallenged with heterologous genotypes developed chronic infections with the genotypes used for rechallenge. These findings suggest that a universally protective HCV vaccine may need to incorporate epitopes from multiple genotypes.
We have investigated the involvement of a cysteine protease in the development of Onchocerca volvulus fourth stage larvae (L4) by testing the effect of cysteine protease inhibitors on the survival of third stage larvae (L3), and the molting of L3 to L4 in vitro. When larvae were cultured in the presence of specific inhibitors, the peptidyl monofluoromethylketones, viability of either L3 or L4 was not affected. However, the inhibitors reduced the number of L3 that molted to L4 in vitro in a time-and dose-dependent manner. Molting was completely inhibited in the presence of 50 -250 M inhibitor. Ultrastructural examination of L3 that did not molt in the presence of inhibitors indicated that new L4 cuticle was synthesized, but there was no separation between the L3 and the L4 cuticles. The endogenous cysteine protease was detected in molting larvae after binding to labeled inhibitors, and by antibodies directed against a recombinant O. volvulus L3 cysteine protease that was cloned and expressed. The enzyme was detected in cuticle regions where the separation between the cuticles occurs in molting larvae. These studies suggest that molting and successful development of L4 depends on the expression and release of a cysteine protease.
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