In previous work, a prototypic recombinant vesicular stomatitis virus Indiana serotype (rVSIV) vector expressing simian immunodeficiency virus (SIV) gag and human immunodeficiency virus type 1 (HIV-1) env antigens protected nonhuman primates (NHPs) from disease following challenge with an HIV-1/SIV recombinant (SHIV). However, when tested in a stringent NHP neurovirulence (NV) model, this vector was not adequately attenuated for clinical evaluation. For the work described here, the prototypic rVSIV vector was attenuated by combining specific G protein truncations with either N gene translocations or mutations (M33A and M51A) that ablate expression of subgenic M polypeptides, by incorporation of temperature-sensitive mutations in the N and L genes, and by deletion of the VSIV G gene to generate a replicon that is dependent on trans expression of G protein for in vitro propagation. When evaluated in a series of NHP NV studies, these attenuated rVSIV variants caused no clinical disease and demonstrated a very significant reduction in neuropathology compared to wild-type VSIV and the prototypic rVSIV vaccine vector. In spite of greatly increased in vivo attenuation, some of the rVSIV vectors elicited cell-mediated immune responses that were similar in magnitude to those induced by the much more virulent prototypic vector. These data demonstrate novel approaches to the rational attenuation of VSIV NV while retaining vector immunogenicity and have led to identification of an rVSIV N4CT1gag1 vaccine vector that has now successfully completed phase I clinical evaluation.
IMPORTANCE The work described in this article demonstrates a rational approach to the attenuation of vesicular stomatitis virus neurovirulence. The major attenuation strategy described here will be most likely applicable to other members of the Rhabdoviridae and possibly other families of nonsegmented negative-strand RNA viruses. These studies have also enabled the identification of an attenuated, replication-competent rVSIV vector that has successfully undergone its first clinical evaluation in humans. Therefore, these studies represent a major milestone in the development of attenuated rVSIV, and likely other vesiculoviruses, as a new vaccine platform(s) for use in humans.
Background and aims. Although salivary gland tumors are not very common, early diagnosis and treatment is crucial because of their proximity to vital organs, and therefore, determining the efficacy of new imaging procedures becomes important. This study aimed to evaluate the efficacy of magnetic resonance imaging (MRI) and color doppler ultrasonography parameters in the diagnosis and differentiation of benign and malignant salivary gland tumors.
Materials and methods. In this cross-sectional study, color doppler ultrasonography and MRI were performed for 22 patients with salivary gland tumor. Demographic data as well as MRI, color doppler ultrasonography, and surgical parameters including tumor site, signal in MRI images, ultrasound echo, tumor border, lymphadenopathy, invasion, perfusion, vascular resistance index (RI), vascular pulse index (PI) were analyzed using Chi-square test, Fisher's exact test, and independent t-test.
Results. The mean age of patients was 46.59±13.97 years (8 males and 14females). Patients with malignant tumors were older (P < 0.01). The most common tumors were pleomorphic adenoma (36.4%), metastasis (36.4%), and mucoepidermoid carcinoma (9%). Nine tumors (40.9%) were benign and 13 (59.1%) were malignant. The overall accuracy of MRI and color doppler ultrasonography in determining tumor site was 100% and 95%, respectively. No significant difference observed between RI and PI and the diagnosis of tumor.
Conclusion. Both MRI and ultrasonography have high accuracy in the localization of tumors. Well-identified border was a sign of benign tumors. Also, invasion to adjacent structures was a predictive factor for malignancy.
Color; doppler; magnetic resonance imaging; salivary gland neoplasms; ultrasonography
Elevated nucleated red blood cell (NRBC) count is introduced as a potential marker of intra-uterine growth restriction (IUGR). To investigate the probable association regardless of any known underlying disease, we aimed to study disturbances in NRBC count in infants experiencing idiopathic IUGR.
Materials and methods
Twenty three infants regarded IUGR without any known cause were chosen to be compared to 48 normal neonates. Blood samples were collected instantly after birth and the same measurements were done in both groups.
NRBC count/100 white blood cells was significantly higher in the IUGR group (P value < 0.001). pH measurements did not reveal any significant difference.
Increased NRBC count in cases of idiopathic IUGR in absence of chronic hypoxia could strengthen its predictive value suggested in previous studies. It could help early IUGR detection and beneficial intervention.
NRBC; IUGR; Peripheral blood smear
Undiagnosed hearing loss can cause disorders in speech and language and delay in social and emotional development.
This study aimed to screen for hearing loss in all newborns born in Babol city during 2009-2011.
Subjects and Methods:
Fifteen thousand one hundred and sixty-five newborns (49% [7430/15165] male and 51% [7735/15165] female) born during a 30-month period in Babol, underwent hearing screening by the otoacoustic emission (OAE) test at the age of 15 days. In infants referred at this stage, an auditory brainstem response (ABR) test was the next investigation. Data analyzed using Statistical Package for the Social Sciences software Version 16 (Chicago, IL, USA, 16) through descriptive statistic method.
In the first screening stage, 10.8% (1648/15165) cases were referred to the second stage for further investigation. 9.4% (154/1648) were lost to follow-up from among the referred cases despite continuous contact and education about the importance of the problem. Among the participants in the second stage, 6.2% (92/1494) were referred to the third stage and underwent ABR and OAE testing. 14.1% (13/92) were lost at this stage. Of the remaining participants, 34.2% (27/79) were diagnosed with a hearing loss. Therefore, the incidence of hearing loss in this study was 1.8/1,000 newborns.
Given the prevalence of hearing loss in this study, implementation of a universal newborn hearing screening program is recommended.
Africa; Hearing screening; Neonate
A bioequivalence study of two verapamil formulations (generic verapamil tablets and Isoptin® tablets) was performed by comparing pharmacokinetic parameters of the parent drug and its major metabolite, norverapamil following a single dose administration of 80 mg verapamil hydrochloride in 22 healthy volunteers according to a randomized, two-period, crossover-design study. Moreover, the feasibility of proving bioequivalence of verapamil oral dosing form by means of norverapamil pharmacokinetic parameters was evaluated. Concentrations of verapamil and norverapamil were quantified in plasma using a validated high-performance liquid chromatography (HPLC) with fluorescence detection. The 90% CIs for the log-transformed ratios of verapamil Cmax (maximum plasma concentration) and AUC0–∞(area under the plasma concentration-versus-time curve from time zero to the infinity) were 73 to 101 and 80 to 103, respectively. Similarly, the corresponding ranges for norverapamil were 80-100 and 84-103, respectively. According to the parent drug data, the 90% confidence intervals around the geometric mean ratio of AUC happened to fit within preset bioequivalence limits of 80–125%, whereas those for Cmax did not. The 90% confidence intervals for both Cmax and AUC of norverapamil met preset bioequivalence limits. The AUC and Cmax of metabolite, when compared to parent drug, showed a much lower degree of variability and the 90% confidence intervals of the metabolite were therefore narrower than those of the parent drug. These observations indicate that bioequivalence studies using metabolite, norverapamil, could be a more suitable and preferable approach to assess bioequivalence of verapamil formulations due to its much lower variability and therefore lower number of volunteers that are required to conduct the study.
Bioequivalence study; Pharmacokinetics; Verapamil; Norverapamil; High variability
Benign maxillo-mandibular tumors and cysts, which are relatively common findings on radiographs, namely the ubiquitous panoramic view, have to be dealt with by dentists on a daily basis.
The aim of this study is to evaluate the panoramic radiographic findings pertaining to benign and tumoral lesions in the maxilla and mandible.
Patients and Methods:
Applying a case series method, panoramic images of 61 patients with cysts, benign tumors and tumor-like lesions in the jaws who were referred to Hamedan dental school between 2009 and 2011 were evaluated by two radiologists. They were both blind to histopathological results as well as the objectives of our study. Lesions were assessed based on their location, periphery, internal structure and impaction on the surrounding structures. Then the obtained data were analyzed using descriptive tables.
Cysts were mostly more common in men despite the equal propensity of both genders to benign tumors. In contrast, women showed a higher frequency of tumor-like lesions. The most common site of involvement was the posterior mandible, with peri-apical tooth lesions as the most prevalent dental association. Radiographically, what we most encountered was unilocular radiolucency pertaining to cysts and benign tumors; nevertheless, tumor-like lesions tended to present with a well-defined radiopacity.
Despite its known shortcomings, like every other diagnostic tool, panoramic radiography can contribute to the early detection of maxillary/mandibular lesions that in turn enable the dentist to devise an appropriate treatment plan.
Panoramic Radiography; Cystic Lesions; Tumoral Lesions; Maxilla, Mandible
Zoonotic Cutaneous Leishmaniasis (ZCL) is an endemic health problem in many rural areas of Iran, with doubled number of incidences over the last decade. Different species of rodents serve as natural reservoir host for ZCL. The disease is considered as a major health problem in rural areas of Mirjaveh, Chabahar, and Konarak Counties of Sistan va Baluchistan Province.
This study describes the identity of Leishmania species, isolated from Meriones hurrianae from Chabahar County using RAPD-PCR methodology.
Materials and Methods
Rodents were entrapped by live traps baited with roasted walnut, tomato, and cucumber during spring and summer. All rodents were identified based on external features including fur color, ears characteristics, tail length, hind feet, body measurements, and internal features of teeth and cranium. Giemsa-stained impressions from rodents’ ears were examined for amastigotes microscopically. The samples from infected rodents were cultured in NNN+LIT medium and then the harvested parasites at the stationary phase were subjected to DNA extraction followed by amplification with RAPD-PCR.
All the 28 entrapped animals were identified as M. hurrianae. Five animals showed to harbor Leishmania parasite by microscopy. Leishmania DNA isolated from five M. hurrianae produced distinctive bands of L. major with four primers. However, the products that were amplified with primers AB1-07, 327, and 329 were stable and reproducible. This is the first report on the isolation and identification of L. major from M. hurrianae from Iran.
Regarding infection rate of 17.8%, M. hurrianae seems to play the major role in the maintenance and transmission of disease to humans in this area.
Meriones hurrianae; Leishmania major; Molecular Characterization; RAPD-PCR; Reservoir Host; Iran
The monthly activity of sand flies, which are vectors of leishmaniasis, was studied from May to October 1997 in three regions (plains, mountainous, coastal) of the Sistan-Bluchistan Province using sticky paper traps. In each village, three houses were selected. 30 sticky traps were installed indoors (bedroom, guestroom, toilet, bathroom) and 30 were installed outdoors (rodent burrows, wall cracks). In total, 8,558 and 1,596 sand fly specimens were collected and identified from outdoors and indoors, respectively. Ten species of Phlebotomus and eight species of Sergentomyia were collected outdoors, and nine species of Phlebotomus and 10 species of Sergentomyia were collected indoors. Phlebotomus papatasi (Scopoli) (Diptera: Psychodidae) was the predominant species found indoors in the plains region (58.4% of insects caught in the region) and was active during the whole study period. The P. papatasi peaks of activity were in early May and early October. Sergentomyia clydei (Sinton) was found to be the most abundant species outdoors in the plains region and comprised 64.7% of the total insects caught in the region. Sergentomyia clydei and S. tiberiadis (Alder, Theodor, and Lourie) were the predominant indoor and outdoor, respectively, species from the mountainous region, making up 19.8% and 35%, respectively, of all the insects caught in the region. Phlebotomus sergenti Parrot is a proven vector of urban cutaneous leishmaniasis, and P. alexandri (Sinton) is a probable vector of Kala-Azar, and both were collected during this study. Phlebotomus papatasi was the most predominant species collected indoors in the coastal region (50.8%), its peak activity was in May. Sergentomyia sintoni Pringle was the most predominant species collected outdoors in the coastal region (36.4%), and its peak activity was in October. Awareness of the peak activity times of sand flies can be useful in developing strategies to control the flies.
ecology; leishmaniasis; Phlebotomus; Sergentomyia
Panoramic radiography has a great place among imaging techniques because of its enormous advantages. One of the characteristics of an ideal imaging technique is to supply precise measurement. The purpose of the current study was to evaluate the accuracy of linear measurements of the jaws on panoramic radiographs.
Patients and Methods
In this study, the vertical distances between the metal markers were measured by panoramic radiography in seven sites of two skulls in various head positions. Then the radiographic measurements were compared with the actual values.
Eighty three percent of the measurements were underestimated, 8.5% were overestimated on panoramic radiography and 8.5% of the measurements had no difference with the real measurements. Overestimation was not greater than 1 mm. The difference between actual and radiographic measurements was less in the posterior areas and in the mandible . In all head positions, the greatest difference between actual and radiographic measurements occurred in the anterior area.
Based on the results of this study, linear measurements on panoramic radiography are more reliable in the posterior areas and may be used in early clinical measurements.
Panoramic Radiography; Linear Measurement; Mandibular Canal; Mental Foramen
Patients with pelvic mass are the most referred patients to gynecologist. The aim of this study was to evaluate the ability of three malignancy risk indices (RMI 1, RMI 2 and RMI 3) and CA-125 to discriminate a benign from a malignant pelvic mass in our region (North of Iran).
This retrospective study was performed on 182 women with pelvic masses referred to Yahyanejad Hospital from 2007 to 2009. Ultrasound scans were scored as one point for each of the following characteristics: multilocular cyst, solid areas, intra-abdominal metastases, ascites, and bilateral lesions. For each patient a total ultrasound score (U) was calculated. The difference of the three RMI was based on the allocation of the U and M scores. The sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) of level of serum CA-125, the RMI 1, 2 and 3 were compared.
Mean age of the patients was 39.9 ± 9.3 years. Most of them were premenopausal (161 women or 88.4%). A significant linear trend for malignancy was found by increasing age, ultrasound score, and serum CA-125. The best performance of CA125 was at a cut-off 88 U/ml, with a sensitivity of 88%, a specificity of 97%, a positive predictive value of 84%, and a negative predictive value of 99%. RMI 1 and 3 at the optimal cut off point of 265 and RMI2 at the optimal cut off point of 355, had a sensitivity of 91%, specificity of 96%, a positive predictive value of 78%, and a negative predictive value of 99%.
In our population we found that there is no statistically significant difference in the performance of three malignancy risk indices (RMI 1, RMI 2, and RMI 3) and CA125 in differentiating between benign and malignant pelvic masses.
Despite their names, simple bone cysts are no longer categorized as cysts since they lack an epithelial lining. However, their nature remains controversial. The internal structure is totally radiolucent, sometimes showing multilocular appearance, although the lesion does not contain true septa and the ridges of bone is produced by the scalloping effect. We presented two cases of histopathologically confirmed simple bone cyst. Radiographic features such as multilocular appearance and significant buccal and lingual expansion are not usual findings for simple bone cyst, whereas evident in our presented cases.
Simple Bone Cyst; Mandibular Pseudocyst; Multilocular Lesion
Visceral leishmaniasis is caused by Leishmania infantum, transmitted to humans by bites of phlebotomine sand flies and is one of the most important public health problems in Iran. To identify the vector(s), an investigation was carried out in Bilesavar District, one of the important foci of the disease in Ardebil Province in northwestern Iran, during July–September 2008.
Using sticky papers, 2,110 sand flies were collected from indoors (bedroom, guestroom, toilet and stable) and outdoors (wall cracks, crevices and animal burrows) and identified morphologically. Species-specific amplification of promastigotes revealed specific PCR products of L. infantum DNA.
Six sand fly species were found in the district, including: Phlebotomus perfiliewi transcaucasicus, P. papatasi, P. tobbi, P. sergenti, Sergentomyia dentata and S. sintoni. Phlebotomus perfiliewi transcaucasicus was the dominant species of the genus Phlebotomus (62.8%). Of 270 female dissected P. perfiliewi transcuacasicus, 4 (1.5%) were found naturally infected with promastigotes.
Based on natural infections of P. perfiliewi transcaucasicus with L. infantum and the fact that it was the only species found infected with L. infantum, it seems, this sand fly could be the principal vector of visceral leishmaniasis in the region.
Leishmania infantum; Phlebotomus perfiliewi transcuacasicus; nested PCR; Iran
The Apgar score as a proven useful tool for rapid assessment of the neonate is often poorly correlated with other indicators of intrapartum neonatal well-being. This study was carried out to determine the correlation between umbilical cord pH and Apgar score in high-risk pregnancies.
This is a prospective cross-sectional, analytic study performed on 96 mother-fetal pairs during 2004-2005 at Shahid Yahyanejad Hospital, which is affiliated to Babol University of Medical Sciences. Apgar score at 1 and 5 minutes after birth was taken and an umbilical cord blood gas analysis was done immediately after birth in both groups. Mothers came with a labor pain and were divided into high-risk and low risk if they have had any perinatal risk factors. Other data like gestational age, birth weight, need for resuscitation and admission to the newborn ward or Neonatal Intensive Care Unit was gathered by a questionnaire for comparison between the two groups. P-value less than 0.05 was considered being significant.
The gestational age and birth weight were the same in high-risk and low risk mothers. Mean umbilical artery blood pH in high-risk mothers was significantly lower than in low risk mothers (P=0.004). Mean Apgar scores at 1 and 5 minutes were significantly lower in high-risk mothers than in low risk mothers (P<0.05). According to the Kendal correlation coefficient there was no significant correlation between Apgar score at 1 and 5 minutes and umbilical cord pH in low risk group (r=0.212, P=0.1). But in high-risk group there was significant correlation between Apgar score at 1st and 5th minute and the umbilical cord pH (r=0.01, P=0.036 and r=0.176, P=0.146, respectively).
Combination of Apgar score and umbilical cord pH measurement in high-risk pregnant mother could better detect jeopardized baby.
Apgar score; Umbilical cord; Pregnancy, High risk; Blood Gas Analysis; Neonate
The control of leishmaniasis, a tropical neglected disease, has been concern of Iranian health authorities due to the increasing number of cases during the last two decades. The objective of this study was to determine deltamethrine residue on the impregnated bed nets using HPTLC technique in a leishmaniasis control program in Iran.
During this experimental study, a total of 130 small pieces of polyester netting were sewn to top, upper, and lower sides of some bed nets and then were impregnated with deltamethrin. The treated bed nets were distributed in Isfahan and Mashhad areas in April 2003. The samples were cut randomly after impregnation intervals. Deltamethrin was extracted using acetone from samples and the extract was applied for spotting onto plates. The plates were developed with n-hexane: ethyl acetate, 90+10(v/v), as a mobile phase in a Camage chamber. The qualifying of residue was observed in UV cabinet with λ=254 nm wavelength. Data were analyzed using SPSS version 11.5. and Stata Version 8. A three way ANOVA was used to compare the means of deltamethrin residue in each area, group and measuring time. The Kruskal-Wallis test was used to compare the means of residue for each of these factors with the control separately.
The retardation factor of deltamethrin was calculated 0.50±0.02. The residues of deltamethrin persisted well on impregnated nets at least for 15 weeks after impregnation. No significant difference could be detected in the loss of residue of insecticide in comparison to measuring times and positions of sampling pieces on the bed nets in these areas.
Based on the results of the present study the use of HPTLC technique is recommended instead of other chromatographic methods for analysis of insecticide residue on the impregnated bed nets.
Leishmaniasis control; Impregnated bed nets; Insecticides; Deltamethrin; HPTLC; Iran
We aimed to develop a PCR-RFLP assay based on available sequences of putative vertebrate hosts to identify blood meals ingested by field female sand fly in the northwest of Iran. In addition, the utility of PCR-RFLP was compared with ELISA as a standard method.
This experimental study was performed in the Insect Molecular Biology Laboratory of School of Public Health, Tehran University of Medical Sciences, Iran in 2006–2007. For PCR-RFLP a set of conserved vertebrate primers were used to amplify a part of the host mitochondrial cytochrome b (cyt b) gene followed by digestion of the PCR products by Hae III enzyme.
The PCR-RFLP and ELISA assays revealed that 34% and 27% of field-collected sand flies had fed on humans, respectively. Additionally, PCR-RFLP assays could reveal specific host DNA as well as the components of mixed blood meals. Results of PCR-RFLP assay showed that the sand flies had fed on cow (54%), human (10%), dog (4%), human and cow (21%), dog and cow (14%), and human and dog (3%).
The results can provide a novel method for rapid diagnosis of blood meal taken by sandflies. The advantages and limitations of PCR and ELISA assays are discussed.
Leishmaniasis; sand flies; blood meal; PCR; ELISA; Iran
The purpose of this study was to evaluate the levels of zinc (Zn), copper (Cu), iron (Fe) and zinc/ copper ratio in the serum of patients with cutaneous leishmaniasis in Qom Province, center of Iran.
Serum levels of zinc and copper were determined by flame atomic absorption spectrophotometer and serum iron concentration was measured by using an Auto Analyzer. The study group consisted of 60 patients with cutaneous leishmaniasis and the control group of 100 healthy volunteers from the same area who were not exposed to cutaneous leishmaniasis.
There were no statistically significant differences in age and body mass index between the two groups. Serum Zn (P< 0.001) and Fe (P< 0.05) levels were lower in patients with cutaneous leishmaniasis than the control group. We also found serum Cu concentration (P< 0.05) in the patient group was significantly higher than that of the control group. However, zinc/ copper ratio (P< 0.001) was lower in patients with cutaneous leishmaniasis than in the control group.
Our data indicated that Zn/Cu ratio was significantly lower in patients with CL as compared to the controls. Earlier reports suggest that, this ratio imbalance could be a useful marker for immune dysfunction in leishmaniasis. There was also strong association of Zn, Cu and Fe with CL. It suggests the use of blood zinc, copper, iron concentration and the copper/zinc ratio (Zn/Cu), as a means for estimating the prognosis of CL.
Cutaneous leishmaniasis; Zn; Cu; Fe; Zn/Cu ratio; Iran
The adult female sand flies (Diptera: Psychodidae) of the subgenus Larroussius are important vectors of Leishmania infantum (Kinetoplastida: Tripanosomatidae) in Meshkinshahr district, Northwest of Iran. Four Phlebotomus (Larroussius) species are present in this area, i.e. Phlebotomus (Larroussius) kandelakii, P. (La.) major, P. (La.) perfiliewi and P. (La.) tobbi. The objective of the present study was to identify and distinguish the females of P. perfiliewi, P. major and P. tobbi, in this district.
Adult sand flies were collected with sticky papers, CDC light traps, and aspirator in 2006. Individual sand flies of this four species from thirty different locations were characterized morphologically and by comparative DNA sequences analyses of a fragment of mitochondrial gene Cytochrome b (Cyt b) and nuclear gene Elongation Factor 1-alpha (EF-1α). PCR amplification was carried out for all three species P. major, P. perfiliewi and P. tobbi in the subgenus Larroussius.
Phylogenetic analyses of P. major populations in this study displayed two different populations and genetic diversity. Spermathecal segment number, pharyngeal armature and other morphological characters of these three species were examined and found to present consistent interspecific differences.
According to our findings, the phylogeny of Cyt b and EF-1α haplotypes confirms the relationships between P. major, P. tobbi and P. perfiliewi as already defined by their morphological similarities.
Phlebotomus; Larroussius; Cytochrome b; Elongation Factor-1α; Morphology; Iran
Although vesicular stomatitis virus (VSV) neurovirulence and pathogenicity in rodents have been well studied, little is known about VSV pathogenicity in non-human primates. To address this question, we measured VSV viremia, shedding, and neurovirulence in macaques. Following intranasal inoculation, macaques shed minimal recombinant VSV (rVSV) in nasal washes for one day post-inoculation; viremia was not detected. Following intranasal inoculation of macaques, wild type (wt) VSV, rVSV, and two rVSV-HIV vectors showed no evidence of spread to CNS tissues. However, macaques inoculated intrathalamically with wt VSV developed severe neurological disease. One of four macaques receiving rVSV developed clinical and histological signs similar to the wt group, while the remaining three macaques in this group and all of the macaques in the rVSV-HIV vector groups showed no clinical signs of disease and reduced severity of histopathology compared to the wt group. The implications of these findings for rVSV vaccine development are discussed.
vesicular stomatitis virus; pathogenicity; neurovirulence; viral vectors; non-human primates; HIV vaccine; intrathalamic
Except for ribavirin, no other antiviral drugs for treating hantaviral diseases have been identified. It is well established that ribavirin will inhibit the production of infectious Hantaan virus (HTNV); however, its mechanism of action is unknown. To characterize the inhibitory effect of ribavirin on HTNV, the levels of viral RNAs, proteins, and infectious particles were measured for 3 days posttreatment of HTNV-infected Vero E6 cells. HTNV-infected cells treated with ribavirin showed a slight reduction in the levels of cRNA, viral RNA, and mRNA populations on the first day postinfection. The amount of cRNA and viral RNA increased to that observed for untreated HTNV-infected cells on day 2, whereas mRNA levels were more greatly reduced on days 2 and 3. Despite the finding of S-segment mRNA, albeit low, three of the viral proteins—nucleocapsid (N) protein and glycoproteins G1 and G2—could not be detected by immunohistochemistry in ribavirin-treated cells. To test the hypothesis that these effects were caused by incorporation of ribavirin into nascent RNA and a resultant “error catastrophe” was occurring, we cloned and sequenced the S-segment cRNA/mRNA from ribavirin-treated or untreated cells from day 3. We found a high mutation frequency (9.5/1,000 nucleotides) in viral RNA synthesized in the presence of ribavirin. Hence, the transcripts produced in the presence of the drug were not functional. These results suggest that ribavirin's mechanism of action lies in challenging the fidelity of the hantavirus polymerase, which causes error catastrophe.
To test whether the protective effects of attenuated simian immunodeficiency virus vaccines in macaques were applicable to the human immunodeficiency virus type 1 (HIV-1)-chimpanzee system, two groups of animals, previously infected with HIV-1(IIIB) or HIV-1(SF2) were each challenged with a heterologous clade B virus, HIV-1(DH12). Following challenge, the parameters measured included virus isolation (from plasma, peripheral blood mononuclear cells, and lymph node tissue); quantitative DNA PCR using primers capable of distinguishing HIV-1(IIIB), HIV-1(SF2), and HIV-1(DH12) from one another; and serologic assays to monitor changes in binding and neutralizing antibodies. In contrast to an HIV-1-naive chimpanzee that rapidly became infected following the inoculation of HIV-1(DH12), the two chimpanzees previously infected with HIV-1(IIIB) resisted repeated and escalating inoculations of HIV-1(DH12), as monitored by virus isolation and PCR. The two animals previously infected with HIV-1(SF2) became infected with HIV-1(DH12) but in contrast to the case with the HIV-1-naive chimpanzee, no cell-free viral RNA was detected in the plasma by the branched DNA procedure and levels of peripheral blood mononuclear cell-associated viral DNA were reduced 35- to 50-fold.