No abstract

The gene encoding the VP8* trypsin-cleavage product of the VP4 protein of porcine rotavirus strain A34 was sequenced, and the predicted amino acid (aa) sequence was compared to the homologous region of all known P genotypes. The aa sequence of the VP8* of strain A34 shared low identity, ranging from 39% (bovine strain B223, P8[11]) to 76% (human strain 69M, P4[10]), with the homologous sequences of representative strains of the remaining 21 P genotypes. Phylogenetic relationships showed that the VP8* of strain A34 shares a common evolutionary lineage with those of human 69M (P4[10]) and equine H-2 (P4[12]) strains. Hyperimmune sera raised to strain A34 and to a genetic reassortant strain containing the VP4 gene from strain A34, both with high homologous neutralization titer via VP4, failed to neutralize strains representative of 15 different P genotypes. These results indicate that strain A34 should be considered as prototype of a new P genotype and serotype (P14[23]) and provide further evidence for the vast genetic and antigenic diversity of group A rotaviruses.

In Bolivia, no studies have been carried out specifically on hepatitis viruses. Thus, their prevalence and circulation patterns are virtually unknown. A seroepidemiologic study was performed from 1992 to 1996 to generate a preliminary idea of the overall prevalence of infection from hepatitis B, C, D, and E viruses (HBV, HCV, HDV, and HEV, respectively) in different Bolivian population groups. Prompted by the data obtained in other areas of Latin America, the study focused on indigenous communities in the Amazon region. In rural areas of the high Andean plateau, HBV infection showed an overall prevalence compatible with medium to low endemicity (11.2%), and no carriers of HCV or HDV antibodies were found. In two high-risk groups in the city of Cochabamba (homeless children and sexual workers), the prevalence of HBV infection was similar (11.6%) and could be considered low by comparison to that of similar population groups in Latin American urban centers. The prevalence of HCV (one positive case, or 0.5%) was similar to that found in similar population groups, although the small number of samples precludes drawing more definite conclusions. As has been noted previously with similar communities in tropical areas of South America, HBV infection is highly endemic in indigenous populations of the Bolivian Amazon (with an overall prevalence of 74.0%), but circulation of HCV has not been detected. It is a well-known fact that HBV is horizontally transmitted and that transmission can take place very early in life, but the mechanisms involved are unknown. By 10 years of age, more than half the population has already had the natural infection that, in approximately 10 more years will have affected virtually the entire population. The very low rate of positivity to HBsAg (1.6%), the absence of viral DNA in samples showing isolated positivity to anti-HBc, and the high prevalence of anti-HBs among individuals who show markers for natural infection (92.4%) suggest vertical transmission plays no role in persistent endemicity. So far, no outbreak of HDV infection has been documented in these communities, but the high endemicity shown by HBV points to the possibility of future outbreaks. Results obtained with tests for the detection of antibodies against HEV suggest that this virus is circulating widely in Bolivia and that it could have caused recent outbreaks in Cochabamba state. Vaccination against HBV in endemic populations is recommended as a short-term measure. Also recommended are actively searching for outbreaks and sporadic cases of hepatitis E in the entire country and performing additional research that will help in assessing the public health consequences of the situation described in this article.

Autoimmune thrombocytopenia is generally caused by autoantibodies against glycoprotein (GP) IIb-IIIa or GPIb-IX and occasionally against GPIa-IIa or GPV. By investigating 38 rheumatoid arthritis (RA) patients on gold therapy, 10 with profound thrombocytopenia and 28 nonthrombocytopenic controls, we showed that in all 10 patients with thrombocytopenia, the platelet autoantibodies preferentially targeted GPV but the presence of gold was not required for their reactivity. Elevated levels of platelet-associated IgG (PAIgG) were observed in 8 of the 10 patients in whom the tests were performed. In 5 patients with sufficient autologous platelets, the GPV specificity of PAIgG was confirmed. Tests with GPV transfectants revealed that the antibodies reacted with GPV independent of GPIb␣, GPIb␤, or GPIX. Autoantibodies recognizing GPV were not seen in the 28 nonthrombocytopenic control RA patients. Thus, GPV seems to be targeted in gold-induced autoimmune thrombocytopenia. IntroductionAutoimmune thrombocytopenia (AITP) in patients with rheumatoid arthritis (RA) on gold therapy is a rare, but severe, event. 1 Platelet autoantibodies generally target glycoprotein (GP) IIb-IIIa or GPIb-IX, 2-4 but GPIa-IIa 5-7 and GPV 8,9 may also be targeted. GPV is a leucine-rich repeat domain protein, present in 1 to 2 stoichiometry with GPIb␣, GPIb␤, and GPIX. 10 GPV-specific autoantibodies occur in 10% to 20% of patients with AITP 8,9 and are particularly evident in defined clinical groups, such as in childhood AITP associated with varicella infection 11 and in multitransfused patients with bone marrow failure. 12 We investigated platelet autoantibody specificity in 10 RA patients with goldassociated AITP to determine whether a particular glycoprotein is preferentially targeted. Our results indicate that the autoantibodies show near exclusive reactivity with GPV. Study designPlatelets and sera from 38 RA patients treated with gold were examined for platelet autoantibodies. Of these 38, 10 had severe AITP; for 7 patients acute-phase platelet counts were available and the remaining 3 samples were from our AITP archive sample bank. The other 28 patients were controls without thrombocytopenia. In 8 of the patients with thrombocytopenia, autologous platelets were available for a direct immunofluorescence platelet-associated IgG (PAIgG) test and in 5 for a specificity investigation by direct monoclonal antibody immobilization of platelet antigens (MAIPA) assay. [13][14][15] Indirect MAIPA tests using the patient's sera were performed in all 10 patients. In one archive case (patient 10), autoantibodies eluted from the patient's own platelets using ether [16][17][18] were also tested.Because it was likely that the patients' sera contained gold at the time of testing, the requirement of gold for antibody reactivity was assessed using protein G-purified IgG. Furthermore, possible augmentation of antibody binding by gold was investigated through the addition of sodium aurothiomalate as a source of gold at physiological concentrations 19 during th...