Royal Perth Hospital, Western Australia, 6001,
Valendar F Turner, John Papadimitriou, Barry Page, David Causer, Helman Alfonso, Sam Mhlongo, Todd Miller, Christian Fiala
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In his rapid reponse "Horizontal Transmission?", 5 March, James Parker wrote: "How does one prove the infectivity of budding virus particles on electron microscopy for instance?. It's a bit like counting angels on the head of a pin !."
We do not know. We have never claimed that the infectivity of a budding particle can be proven "on electron microscopy".
James Parker wrote: HIV as an infectious agent is questioned by the Perth Group. Indeed doubt has been expressed concerning the very existence of exogenous retroviruses. And yet we have been this route before. Thirty years ago similar doubt was entertained that the retrovirus FeLV (cat leukaemia virus) was horizontally transmitted in field situations (Schneider R; Status report: feline leukaemia (C) J Am Vet Assoc 164 1070, 1974)."
Although any scientist can be wrong, Schneider is not one of them. To date nobody has proven that the Feline lymphosarcoma virus (FeLV) is "horizontally transmitted in field situations" In 1973 Hardy, Essex and their colleagues stated: "Recent epidemiological studies on feline lymphosarcoma gave no evidence for horizontal transmission of FeLV but cases of apparent contact infection with FeLV have been observed in laboratory cat colonies". (Hardy et al Nature 1973; 244:266-269). In the 1976 paper they stated: "….only 0.31% of the stray cats…were infected". that is had a positive antibody test. (Hardy et al Nature 1976; 263:326-328). (emphasis ours)
James Parker wrote: "Two years later Hardy and associates (Nature 263 326 1976), in a test and removal program, demonstrated that removal of infected cats reduced the subsequent incidence of disease in multiple cat households. This did not occur in control households where infected cats were not removed."
The "removal of infected cats" and subsequent reduction in the "incidence of disease in multiple cat households", is not proof that the FeLV is horizontally transmitted or that the cause of the disease, lymphosarcoma, is FeLV.
The causes of the disease may not be infectious, it may be congenital or some cats may be susceptible to factors present in the households or the diet. If infectious the cause may be the Feline immunodeficiency virus (FIV) (K Hartmann et al, 1998. Feline Immunodeficiency Virus Infection: an Overview. The Veterinary Journal 155, 123-137).
In 1973 Hardy et al stated: "Whether the exogenous FeLV induces lymphosarcoma or activates an endogenous virus which does so, is an open question". (Endogenous retroviruses can be activated not only by other retroviruses but also by many other factors, infectious and non-infectious).
Furthermore and most importantly, neither Hardy et al, nor anybody else, has proven that the antibody test used by Hardy et al was FeLV specific. In this case the possibility cannot be excluded that the antibodies which reacted with the antigens in the FeLV antibody test were not directed against FeLV or any other retrovirus, but:
(i) auto-antibodies appearing as a result of the lymphosarcoma or the many other diseases from which the household cats were suffering;
(ii) antibodies directed against non FeLV antigens to which the household cats but not the cats in "field situations" were exposed;
(iii) antibodies directed against the FIV or endogenous retrovirus. Since in the FeLV antibody tests the antigens used are gag antigens, this is most likely.
James Parker wrote: "While a 'test and removal' program in HIV/AIDS has been deemed unethical, it has been carried out in one country (Cuba) with fairly dramatic results. (Schepper-Hughes N, Lancet: 1993 342 965-067) It is of interest that the successful and impressive 'ABC-program' of HIV prevention in Uganda according to it's president had it's genesis in Cuban advice".
In Cuba a small number of "HIV" positive individuals (no more than 927 up till June 1993), "most of them homosexuals" were put in "partial social isolation". "The primary goal was therapeutic, and protection was secondary". In the reference which James Parker cites one reads: "Many factors have contributed to the control of AIDS in Cuba, apart from its controversial public health program; the absence of intravenous drug use, a climate of sexual puritanism and of hostility (leading to an exodus of gay Cubans) and easy access to abortion" (Schepper-Hughes, Lancet 1993; 342:965-967).
(i) as far as we know, no removal program has ever been implemented;
(ii) there is no evidence for a "successful and impressive" prevention of "HIV" in Uganda (Parkhurst J, Lancet 2002; 360:78-80);
(iii) no amount of sex education has any effect on the incidence if "HIV" seropositivity in Uganda (Kamali A et al Lancet 2003;361:645-52).
James Parker wrote: "Whatever the mode (and opinion of the Perth group), it does appear that AIDS is transmissible. The dangers of 'denialism' of this fact cannot be over emphasised".
Could he please give us one epidemiological study with evidence which proves "that AIDS is transmissible". Could he please tell us which of the Perth group's views are dangerous and why?
Competing interests: None declared