With the objective of monitoring the distribution of HIV-1 subtypes and circulating recombinant forms (CRFs)in South America, population-based surveillance studies were performed in seven countries. Peripheral blood mononuclear cell, filter paper, fresh blood, and cocultivation samples were collected from HIV-positive patients from Colombia, Ecuador, Peru, Bolivia, Chile, Argentina, and Uruguay, during a 7-year period(1995-2001). DNA was prepared and HIV envelope subtypes were determined by heteroduplex mobility as-say and DNA sequencing from 1289 HIV-positive samples. While subtypes B and F were the most commonly observed subtypes, two CRF02_AG strains were detected, in Ecuador. This is the first report of the existence of this CRF in South America.

The association of porcine reproductive y respiratory syndrome virus (PRRSV) and pneumonia in fattening pigs from well managed pig farms in the Lima valley was determined through viral antigen detection, observation of microscopic lesions in lung and mediastinic lymph-node (MLN) tissues, by immunofluorescence test and conventional histologic procedures. Pneumonic (n=l02) and normal (n=69) lung and MLN tissues of 20 to 23 week old pigs from 23 farms were collected at local slaughterhouses. PRRSV antigen was detected in 14.7 % (151102) of neumonic lung and MLN samples. The virus was most prevalent in lung (47%), followed by lung and MLN (33%) and MLN (15%) samples. PPS infection was found at twenty six percent (6/23) of the farms sampled, and lung tissue (n=29) of pigs from these farms showed high prevalence of viral antigen (51.7% ). The most frequent histopathological lesions were acute superative pheumonia and subacute bronchopneumonia, anda statistically significant relationship (p<0.05) between PRRSV infecction and pneumonia was found. These results suggest that PRRSV plays an importnat role in predisposing fattening pigs to secondary bacteria! infection.